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Traffic Study for Transportation Sub-Committee of Cupertino Citizen's Goals Committee - 416.07r I 1//6 0 7 I 1 1 TRAFFIC STUDY A Review of Work to Date 1 I Prepared for Transportation Sub-Committee ' of Cupertino Citizen' s Goals Committee 1 IPrepared by IICH2M HILL March 1982 t 1 11 L_ I CH2M : H I LL iengineers planners economists I scientists IIMarch 15, 1982 F157 41.A0. 00 II Mr. Dick Childress, Chairman I Transportation Subcommittee Cupertino Citizen 's Goals Committee Public Works Department II 10300 Torre Avenue Cupertino, California 95014 Dear Mr. Childress: IWe .are pleased to submit our final report regarding CH2M HILL 's review of the City 's ongoing Traffic Study. The report II completes our activities on the project and summarizes our findings. We have concluded that the procedure used by City staff in II analyzing and projecting traffic volumes, while somewhat unorthodox, made full use of existing data from computerized countywide and Bay Area transportation models, utilized I realistic assumptions and techniques, and arrived at reason- able estimates of 1990 traffic volumes on major corridors in Cupertino. We are somewhat less comfortable with the City li staff 's procedure of "factoring up" existing intersection conditions to form the primary basis for decisions on fairly definitive roadway improvements. The level of detail asso- ciated with some of the recommended improvements may be beyond the level of confidence associated with the data used in the supporting calculations. We believe the report adequately addresses the issues that will be important to the members of the Subcommittee as they prepare their recommendations to the Citizen's Goals Committee and ultimately to the City Council . We have enjoyed working with the Subcommittee on this project. Please let us know if we can be of further service. I Sincerely, I ".1(--- 9 Richard Luebbers, P.E . IIProject Manager Enclosure cd I San Francisco Regional Office [ 2200 Powell Street,Emeryville,California 94608 415/652-CH2M I I .. IIOM CONTENTS I Page 1 . INTRODUCTION 1-1 1 Study Objectives 1-1 Scope of Work 1-1 Study Overview 1-1 Data Sources 1-2 I2 . REVIEW OF CITY TRAFFIC STUDY 2-1 Use of Baseline Data 2-1 1/ ABAG-MTC Regional Model 2-1 County Traffic Model 2-2 City Traffic Model 2-4 I Current Traffic Volumes 2-6 Traffic Projection Procedure 2-6 Conversion P .M. Peak Volumes 2-7 Need for a Postcard Survey 2-8 II Sensitivity Analysis 2-8 Summary 2-9 I 3 . REVIEW OF CITY RECOMMENDATIONS 3-1 Additional County Data 3-1 Route 85 Extension 3-2 Need for Route 85 Extension 3-6 I Stelling Road 3-11 De Anza Boulevard 3 11 Vallco Park Area 3-12 II Summary 3-12 I 11 I I II 1 I OHO Chapter 1 OHM INTRODUCTION I This study was conducted by CH2M HILL at the request of the 1 II Transportation Sub-Committee of the Citizen' s Goals Committee for the City of Cupertino. Our study consisted of a review of the City' s ongoing traffic forecasting and analysis activities. The Sub-Committee and City staff participated I IIin the review process, through attendance at three joint meetings. ISTUDY OBJECTIVES The review of the Cupertino Traffic Study was directed toward two main objectives : ( 1) to verify the technical ill II work that has been performed by City staff, and ( 2 ) to clarify the procedures, conclusions, and recommendations contained in the City' s reports. ilThe successful accomplishment of both of these objectives is essential to the adoption and implementation of a transporta- ' tion plan that truly meets the needs of the City of Cupertino. SCOPE OF WORK IThe scope of work for this study was established based on the need to perform the work from two perspectives . The first perspective evaluated the overall methodology employed 1 in the study. The methodology was depicted in flow chart form, breaking the total effort down into a series of indi- vidual tasks. The methods employed were reviewed for their II conformance with state-of-the-art transportation planning techniques, their ability to achieve desired results, and their compatibility with existing Association of Bay Area 1 Governments/Metropolitan Transportation Commission (ABAG/MTC) Iand Santa Clara County transportation planning efforts . From another perspective, the work performed in each of the I individual tasks was reviewed. Items that were reviewed included: the source of data and its appropriateness for the intended use; the assumptions utilized; the method of I handling or transforming the data; and the conclusions drawn from the task. Through this process it was possible to determine the reliability of the output of each task. ISTUDY OVERVIEW Transportation planning procedures can range from very I sophisticated to very basic . The sophisticated procedures use a full set of computerized programs for trip generation, trip distribution, modal split, and traffic assignment. At I the other extreme are procedures that utilize basic growth factors that are applied to current traffic volumes. 1-1 1 II I I The intent of the City staff was not to pursue an extensive, sophisticated modeling procedure, but to work within the framework of existing County and Bay Area transportation models. Therefore the review described in this report was ' intended to be within the level of sophistication that the City used for its model . ill CH2M HILL ' s review basically focused on additional verifica- tion of the process used by the City. The review was based on the use of existing, readily available data . No new data I was collected or prepared with the exception of a special origin-destination trip table produced by Santa Clara County and the Metropolitan Transportation Commission mid-way through the study. IIDATA SOURCES The review process included extensive review of previously completed reports pertaining to development and transporta- tion in Cupertino, Santa Clara County and the Bay Area . The 1 review of reports, coupled with contacts with a number of persons directly involved with past and current transporta- tion planning activities enabled us to determine procedures used in previous related studies . This review provided the I necessary background information to form the basis for our conclusions. Listed in Appendix A are various personal contacts and reports reviewed during this study. I II I II II II II 111 I 1-2 I 'H Chapter 2 •111 REVIEW OF CITY TRAFFIC MODEL The first phase of the study was concerned with the procedures I and resource data used to develop the City traffic model . The review was made by evaluating existing related reports, contacting persons involved in related studies, and through ' discussions with City staff. Ten separate, but interrelated, tasks were identified. Each of these is discussed below. Figure 1 represents a work flow diagram for the City traffic model . The circles represent input data from various sources and the rectangles represent actual work elements performed by City staff. ' USE OF BASELINE DATA The City used data from the County' s 1975 traffic model that was based on population/employment data furnished by cities ' and counties throughout the Bay Area. Initial County runs were made with predicted 1990 employment data that turned out to be very near actual 1981 levels. Therefore , the ' original estimated 1990 employment projections were too low. City staff took this into consideration while developing their model and adjusted City of Cupertino population and employment data to be in line with current City projections for 1990. Subsequently, the County model was run again in 1981 using ' updated population and employment data that was more in line with current trends . Most of the changes in Santa Clara County were made for areas north and east of Cupertino. ' This appears to have caused only minor changes in traffic projections in the vicinity of Cupertino. Therefore, the use of the original baseline data by the City, with adjust- ment for local plans, appears to be appropriate . ' ABAG-MTC REGIONAL MODEL The Association of Bay Area Governments (ABAG) and the Metropolitan Transportation Commission (MTC ) , regional governmental agencies for the San Francisco Bay Area, have II an ongoing traffic modeling effort for the nine counties around San Francisco Bay. ' Demographic data used in these models are obtained from the State of California Department of Finance and directly from Bay Area counties and cities. ' The MTC transportation model consists of 440 zones , of which 88 zones are in Santa Clara County. The MTC models are state-of-the-art for both regional transportation analysis ' ( large transportation facilities) and for regional demog- raphic projections. ' 2-1 11 II IIPHASE ; PAS- PHASE III 1/ * ABAG-MTC VALL CC SANTA CLARA PARK COMPUTE 199C 11 vALLEY CORRIDOR SURVEY VOLUME GROWTH EVALUATION AT SCREENLINES NETWORK ICUPERTINO * * SOUND-OFF * * _ _* * * SURVEY COUNTY COMPUTE 1990 PM 1/ COUNTY-MTC ACTUAL VS MODEL CALCULATE LEVEL RTDP PHASE EXTRACT DATA SPLIT ZONE PROJECT COMPUTE 1980 TO PEAK STREET VOLS. STUDY COUNTY MODEL PROJECT 1990 INBOUND L OUTBOUND OF SERVICE FOR I STUDY (1974) �� FROM COUNTY 1...► limil. 10 INTO ZONES 1=414- 1990 TRAFFIC 4.4m. 1990 TRAFFIC BASE & ALTERNATE RECOMMENDATIONS (TAZ'S) COUNTY-UTPS SUPERZONE 10 VERIFICATION AM PEAK TRIPS 10A AND 10B 1975 AM & PM PEAK AM PEAK GROWTH STREET NETWORKS CRITICAL / MODEL VOLUMES (HWY 85) INTERSECTIONS / CITYI/ TRAFFIC COUNTS I ADJUST VOLUMES AND( ITYL AND PMOURAK CONVERT 1990 UPDATED USE ELEMENTS LICENSE LAND USE USING ROADWAY (DEMOGRAPHICS) PLATE ELEMENT CONVERSIONS PM PEAK BALANCING SURVEY TRAFFIC ANALYSIS I/ II LEGEND ❑ PROCESS / - O INPUT * PROCESS VALID I I IFIGURE 1 CITY OF CUPERTINO CH2M TRAFFIC STUDY FLOWCHART CHILI_ F15740.A0.00 1 i IIn addition to regionwide analysis, the MTC models allow for in-depth evaluation in identified problem areas . This ,.nalytical ability was used by the MTC in the Santa Clara ' Valley Corridor Evaluation (SCVCE ) Study. Santa Clara Valley Corridor Evaluation Study ' The Santa Clara Valley Corridor Evaluation Study was under- taken to evaluate 1990 transportation needs on a corridor basis in Santa Clara County, and to define needed countywide transportation improvements. A wide range of potential 1990 development patterns and transportation systems was identi- fied . A systematic procedure was established to eliminate I from further consideration the least favorable or acceptable alternatives. ' The study identified three proposed projects that would directly affect the City of Cupertino. These are: 1. The addition of two lanes to I-280 between Route 17 and Magdalena Road. 2 . Protection of the right-of-way needed to extend Route 85 ' from its present terminus at Stevens Creek Boulevard in Cupertino to Route 101 in South San Jose. 3. Construction of an extension of the Route 85 freeway from Stevens Creek Boulevard to DeAnza Boulevard in Cupertino. These proposed improvements were incorporated into the County's traffic model to establish a baseline network for 1990 . They were used for planning purposes only and do not ' represent committed improvements. In this review it was assumed that the first of these three projects will be implemented without further action by the City of Cupertino. ' Recommendations have been made in Chapter 3 that affect Projects 2 and 3 . COUNTY TRAFFIC MODEL Santa Clara County developed a morning ( a.m. ) peak hour travel projection model for use in evaluating countywide ' traffic flow. The County model utilized data generated in the Santa Clara Valley Corridor Evaluation Study. The model version used by the City in their traffic study was based on ' 13 superzones within the County, each containing a number of smaller traffic analysis zones. The County used the UMTA Urban Transportation Planning System (UTPS) program package for their modeling effort. 11 2-2 11 II Standard UTPS trip generation, distribution, assignment, and capacity restraint techniques were used in the County model . These techniques are well documented and conform to current state-of-the-art methodology for traffic projections. Assignment runs made by Santa Clara County were based on the proposed street networks included in the SCVCE study. At I this time , all County model assignments have been made using the same basic street network in the Cupertino area, with the exception of Route 85 . Assignments for three alterna- ' tives for Route 85 have been made by the County model . These are : o A six-lane freeway to Route 101 ' o A four-lane expressway to Route 101 o A four-lane expressway to De Anza Boulevard I After initial model runs were made, the County updated population and employment data to reflect current County development trends. Data from the SCVCE Study indicated County employment levels for 1990 that were near current 1 II1981 levels . Therefore, it was concluded that projected 1990 employment levels from the SCVCE Study were low and required adjustment to a realistic level . Data extracted IIfrom the county model for use by the City of Cupertino in their study (begun in 1979 ) were based on the initial SCVCE projections . Because of this, the City increased employment II levels as a part of their modeling effort . An updated County traffic model run has been prepared since the City initiated their traffic study. The Guadalupe II Corridor Study ( published in October of 1980 ) reflects changes in population, housing, and employment from those in the SCVCE Study used as a base by the City. The Guadalupe IICorridor Study was also done as a joint effort by the County, MTC, and ABAG and the updated demographic data used in the study were used as input into the MTC-ABAG regional model . The demographic data was obtained directly from cities within the County and represented the best information available for use in a traffic model . preparing ' Data from the updated County model was obtained by CH2M HILL during our review to check for changes in traffic projections in the Cupertino area . The updated model indicates that I most of the growth in traffic volumes will occur in the north and east sections of Santa Clara County. Traffic projections for Cupertino streets are nearly the same as, or very slightly less, than indicated by the older County IImodel . Work done by the City staff involving use of the older model data still appears to be reasonably valid. 1 I 2-3 ICITY TRAFFIC MODEL The basis for the City model was data extracted from the I Santa Clara County SCVCE model . Superzone 10 from the County model included the City of Cupertino and adjacent areas. ISuperzone 10 data from the County model represented a.m. peak hour travel . The County chose to use a.m. peak trips I because they are simpler to model . During the a.m. peak, most trips are for work, while in the p.m. peak, several trip purposes are involved in the total traffic flow, requir- ing a more complex modeling effort. IIIt was the City' s desire to develop a model for the p.m. peak hour, which typically has higher traffic volumes and I is, therefore, more critical in terms of the level of service (LOS) provided by roadway facilities . Validity of Extracting Superzone 10 Data IIData from a single zone or zones within a regionwide model usually provide a sound basis for a small area analysis, II such as the City of Cupertino. Most transportation planning packages for urban areas include a technique to focus in on a subarea in order to provide a more detailed analysis. Trip generation and trip distribution for the 13 superzones II included in the County model were prepared using standard techniques and, therefore, provided a good estimate of overall traffic patterns for Cupertino. IIVerification of County Model I Verification (by City staff) of output from the County model consisted of four elements : location of residence of Zone 10 employees ; location of employment of Zone 10 residents; a cordon comparison between actual traffic volumes and volumes IIfrom the County model output; and comparisons based on a license plate survey. I The employee residence check was based on returns from more than 6,400 employees within Vallco Park, plus 2, 300 from Four Phase , and together represent approximately 45 percent I of current nonretail employment levels . This sample size and distribution provides a valid check of residence location for persons travelling in the a.m. peak hour. 1 The verification of job location of Cupertino residents was based on a relatively small sample ( 339 responses ) . It is also possible that the responses could have been biased I because it is a voluntary return. In this type of survey, it is possible that a certain segment or category of residents 2-4 i 111 I may tend to respond at a higher rate than other segments, resulting in a sampling error. Thus, the results of this verification check must be used carefully. Regardless of I the questions raised, this location of employment check appears to validate the County model . The third verification check--the comparison of actual and I model generated volumes crossing Zone 10 boundaries--appears to give valid results that verify the trip generation from the County model ( 42,600 actual vs. 42, 744 from the model ) . ILicense Plate Survey I The City, in cooperation with Caltrans and MTC, performed a license plate survey to determine the type of trips compris- ing p.m. peak traffic on Cupertino streets. The license plate survey was conducted by recording license plate numbers I of southbound sample vehicles crossing a screenline along Stevens Creek Road. The location of registration of the observed vehicles was obtained from official state registra- ' tion lists . Several assumptions were made by City staff about the trip being made at the time when the license plate nunber was observed. Each assumption appears to be logical ; however, as a group they tend to leave some doubt as to the IIaccuracy of the survey itself. In analyzing the license plate study, the City staff divided 11 the location of registration of observed vehicles into three general categories : ( 1 ) those within Cupertino (zip codes 95014 and 95129 )--5,879 vehicles; ( 2) those located north of I the screenline outside Cupertino--2 , 339 vehicles ; and ( 3 ) those located south of the screenline outside Cupertino--2, 132 vehicles. The City' s first major assumption was that most of Category 1 trips should be considered as "Cupertino IIgenerated" (primarily residents returning home ) . It was also assumed that at least part of the Category 2 IItrips would include trips going to De Anza College and would also be considered as "Cupertino generated . " A study of evening peak traffic volumes entering the College from the I north amounted to 1,765 trips . The remainder of the Category 2 trips ( 574 trips) could be either local or through trips. The third assumption about the license plate survey was that I Category 3 trips would mostly be through trips, as far as Cupertino is concerned. I Assuming that all Category 1 trips were oriented to Cupertino, and that all Category 3 trips are through trips with regard to Cupertino, a range in the percent of trips passing through Cupertino, was calculated to be 21 to 26 percent, according I to the license plate survey. I 2-5 I IThe County model predicted 2 , 300 trips moving through Super- zone 10. This amounts to 21 percent of all trips crossing the Stevens Creek Road screenline . The results of the I license plate survey appear to further verify the County model . ICURRENT TRAFFIC VOLUMES City staff furnished CH2M HILL with traffic count data I covering the period from the early 1970 's to the current time . At locations where both 1975 and 1981 data were available, the amount of peak hour growth was found to vary from location to location; however, the overall growth at I the locations checked indicates about 10 to 12 percent growth. Thus, the contention of City staff that there has been only a small increase in peak hour traffic between 1975 and 1980 may be only partially correct. However, the growth 11 that has occurred has been on a Citywide basis and has occurred at approximately the rate that would normally be expected for a community such as Cupertino. The 1975 traffic II model , therefore, appears to have provided a realistic base for the City's study. ITRAFFIC PROJECTION PROCEDURE The ABAG/MTC and County 1990 traffic projection procedure , I based on growth in population and employment, is a logical procedure normally used in studies of this type . The City used this projected data, compared with existing data, to project traffic volumes on City streets to 1990 levels. IProjected Traffic Growth I Based on screenline comparisons of projected traffic growth between 1980 and 1990, the City has selected an overall traffic growth factor of 1 .30. The screenline analyses , I comparing 1980 and projected 1990 growth indicated that traffic growth will vary in different parts of Cupertino. Therefore, the City varied the growth factors by location, with a net overall average growth of about 30 percent. The I traffic growth factors were applied to current traffic volumes on major streets in Cupertino to project 1990 volumes. IA factoring procedure, based on projected traffic growth across screenlines, is appropriate for estimating corridor volumes. However, the reliability of using such a procedure determine individual street volumes appears to be question- Ito question- able . City staff has recognized this weakness and has at least partially compensated for it by "testing" a range of estimated future volumes at critical intersections. 2-6 II , IFor example, an intersection level of service (LOS) analysis was performed using variations in the magnitude of the critical volumes. Using this procedure enabled City staff I to judge the sensitivity of the estimating procedure . This appears to be a satisfactory method of analyzing potential LOS problems in future years at intersections . However, it 1 II' will be necessary to supplement this analysis with current local data when designing specific intersection improvements . I City staff is presently engaged in the development of a computer-assisted traffic assignment technique that will provide a faster and more consistent method of estimating future traffic volumes. This should improve the City traffic Imodel results and analysis capability. For alternative street networks that included added lanes, the 1990 volumes across screenlines were allocated based on 1111 an intersection level of service analysis. This appears to be a valid procedure at this time , given the limitations discussed above . The computer-assisted traffic assignment I technique under development by City staff ( outlined above ) should also improve this element of the City model . I CONVERSION TO P.M. PEAK VOLUMES An assumption was made in the City model that the morning I (a.m. ) work trips would be reversed in the evening (p.m. ) and would be of equal magnitude . In addition, the p.m. peak traffic would include other traffic , such as shopping , personal business, and other trip purposes including De Anza ICollege trips. Checks of a.m. home-to-work and p.m. work-to-home data from I three studies of other urban areas indicates that the number of trips varied by 3 , 7 , and 10 percent, respectively. In two cases, the p.m. work-to-home trips were higher and in IIthe other case, the a .m. home-to-work category was higher. These data also indicated that about 80 percent of the a.m. peak trips were made for the purpose of home-to-work. The II County model included about 15 percent "other" trips in addition to home-to-work trips. A comparison of model trips with actual traffic counts made by City staff indicated that I the County model traffic and actual traffic were approximately equal for a .m. conditions. I City staff determined that p.m. peak volume are about 20 per- cent higher than a.m. peak volumes, based on comparisons between actual a.m. and p.m. peak hour counts. Therefore , the City' s methodology for obtaining p.m. traffic volumes by I reversing the a .m. trips and adding 20 percent more trips for additional home-to-work and other trips in the p.m. peak appears to be quite logical , particularly on a Citywide I 2-7 I _411.44 City of Cupertino City of Cupertino 10300 Torre Avenue Cupertino, California 95014 (408) 252-4505 TO: The City Council July 20, 1982 The Planning Commission City Manager Chairperson, Citizens Goals Committee Paul Sonnenblick, President, West Cupertino Homeowners Association Planning Director FROM: Bert J. Viskovich, Director of Public Works •1 SUBJECT: ADDENDUM TO CH2M HILL TRAFFIC REPORT Submitted toyou foryour files is a copyofthe addendum to the CH2M Hill traffic report. As you may recall, even though the consultant's report verified the staff's traffic report, a slight difference in levels of service existed between the staff's and the consultant's reports. The difference of 1/2 to 1 level of service in letter designation tended to yield slightly different conclusions and therefore different recommended capital improvements. This has now been clarified in the addendum. The staff's and the consultant's conclusions are now essentially the same. The main difference was resolved just recently during the meeting of the traffic task force when it was discovered when both city and consultant arrived at the same weighted average delay for a particular intersection, but when the consultant assigned a letter to it, his method allowed 28-35 seconds for "D" level while staff, using a different method al- lowed 45-60 seconds for the same level. It is hoped that the information presented to you completes the final evaluation of the staff's traffic report. BJV:sm attach. IL CH2M :CH ILL UCWORKS e gineers JUL 161982 peconomists WAWA scientists July 13, 1982 F15741 .AO. 00 Mr. Dick Childress, Chairman Transportation Subcommittee Cupertino Citizens ' Goals Committee Public Works Department 10300 Torre Avenue Cupertino, California 95014 Dear Mr. Childress: Subject: Addendum to Traffic Report Please refer to our March 15, 1982 Report regarding CH2M HILL' s review of the City of Cupertino ' s in-house Traffic Study. The Report summarized our analysis of the City' s work and presented relevant findings. As you will recall, we expressed concern in the Report and at the March 16, 1982 City Council/Planning Commission meeting, that the City' s method of evaluating operating conditions (CAPSSI) consistently produced higher levels of service than the Transportation Research Board, Circular 212 (TRB) method that we normally use. This, in turn, impacted the projected need for future transportation facilities in Cupertino. Additional investigations, since our Report was presented, have produced information of importance to the Transportation Subcommittee. This addendum describes the new information and indicates the impacts that it repre- sents to our original Report. We have carefully compared the CAPSSI and TRB methods of cal- culating level of service in an attempt to determine the apparent differences. In general, the two methods treat intersection configuration, traffic volumes, critical vehicle movements, signal phasing, and other parameters in very similar ways. The major difference between the two methods is related to the type of information obtained by the calcula- tions and to the manner in which the results of the analysis are interpreted. The TRB method produces data to compare the volume of traffic on conflicting movements to the theoretical capacity of the intersection. The CAPSSI method performs similar analysis but relies on measurement of average delay for all vehicles at the intersection to determine level of service. San Francisco Regional Office 2200 Powell Street, Emeryville,California 94608 415/652-CH2M Mr. Dick Childress, Chairman Page 2 July 13, 1982 F15741.A0. 00 The difference between the two methods can best be seen in the amount of delay associated with the City' s design level of service (LOS D) . By definition, Level of Service D occurs when traffic movements at the intersection result in some congestion, and therefore delay, but the length of delay experienced is thought to be tolerable by most motorists. The CAPSSI method utilizes a range of 45 to 60 seconds of average delay to define LOS D. The TRB method indicates that the average delay associated with the calculations for LOS D is in the range of 28 to 35 seconds. Review of existing data and observations of current operating conditions indicate that many transportation facilities in and around Cupertino are currently operating at LOS D conditions with delay ranges that are closer to the CAPSSI method than to the TRB method. Research by others also indicates that drivers in highly urbanized areas, such as the Bay Area, generally find higher average delays more tolerable than their less urbanized coun- terparts. The CAPSSI method is based on urban conditions while the TRB method currently reflects average conditions for transportation facilities of all types and locations. It appears , then, that the definition of tolerable delay in the CAPSSI method, although higher, may be more appropriate for intersections in Cupertino. The CAPSSI method, by allowing higher delays during peak periods, also permits a larger volume of traffic to use the intersection at any given level of service. This, in turn, can affect the type and extent of physical improvements that may be necessary to accommodate the volume of traffic expected at some future time. With this in mind, we have reviewed our Report and provide the following comments for your considera- tion. o The method of capacity analysis does not affect the transportation planning aspects of the City' s Traf- fic Study, therefore, all information in our Report, up to and including page 3-6, remains unchanged. o Need for Route 85 Extension (pages 3-6 to 3-10) : The discussion regarding level of service calcu- lation techniques in this section has been super- seded by the discussion above. With the higher range of tolerable delay, it is likely that the DeAnza Corridor would be able to accommodate much of the projected north-south traffic at the existing Comprehensive Plan densities. DeAnza would have to be improved to an 8-lane facility from I-280 to Bollinger. In this configuration, it would operate at LOS D during peak hours while carrying the through traffic that would otherwise use a new Mr. Dick Childress, Chairman Page 3 July 13, 1982 F15741.A0. 00 facility in the Route 85 corridor. Some of the through traffic using Stelling may divert to an improved DeAnza but only to the extent that overall travel times on the two facilities were comparable. In fact, the higher delays on DeAnza may make alter- native routes, such as Stelling, more attractive until a balance in travel times is obtained. If Cupertino develops at an increased intensity, the DeAnza Corridor would continue to accommodate its share of the additional traffic assuming con- comminent physical improvements. Stelling and Bubb would also receive additional traffic as the overall system travel times balanced. Some additional north-south capacity would be required at the higher intensities of development on Bubb and Stelling as well as DeAnza. The improvements could be addi- tional through lanes on Stelling, major intersection improvements on DeAnza, roadway and intersection improvements on Bubb (or a combination of the above) , and/or a new roadway in the Route 85 corridor. It appears that a high capacity 2-lane roadway in the Route 85 Corridor would be sufficient to take much of the potential traffic burden, resulting from higher development intensities, off of Bubb and Stelling, and to a lesser degree from DeAnza. o Stelling Road (page 3-11) : If DeAnza was improved to eight lanes with an inter- connected signal system, it appears that the future traffic pressure on Stelling under existing Compre- hensive Plan densities may be less than we earlier thought. Stelling would, however, continue to carry some through traffic along with local traffic. Improvement to four continuous lanes with adequate turn lanes, between Steven' s Creek and Rainbow, would aid the flow of traffic, reduce queue lengths, and minimize congestion. If a new roadway was built in the Route 85 corridor, Stelling would carry significantly less through traffic but would remain an important arterial serv- ing local traffic. Improvements to a continuous four-lane facility would still be desirable although less improvement would be required at intersections . Severing Stelling at Prospect does not appear to be in the best interests of traffic generated in South and West Cupertino areas. Mr. Dick Childress , Chairman Page 4 July 13 , 1982 F15741 .A0 . 00 With the improvement of DeAnza to eight lanes , Bubb, McClellan, and Rainbow may not have to accommodate as much through traffic as earlier thought with existing Comprehensive Plan densities . Improvements to these roadways should be in keeping with new developments in the West Cupertino area. o DeAnza Boulevard (page 3-11) : As discussed earlier, DeAnza, if improved to four lanes each way between I-280 and Bollinger, appears to be able to accommodate most of the growth in north-south traffic if the CAPSSI method is used to determine future operating conditions . It should be remembered that longer delays are associated with the CAPSSI method, making alternative routes appear more attractive. If a new roadway was built in the Route 85 corridor it would attract most of the traffic diverted from DeAnza. Without a new Route 85 roadway, Stelling and other north-south streets would continue to receive some overflow from DeAnza. Obviously, the higher the intensity of development , the more traffic would attempt to minimize travel times by avoiding DeAnza. The interconnected traffic signal system on DeAnza will help to reduce delays to north-south vehicles , minimizing the propensity to divert to other facilities , but will not eliminate diversions entirely. o Vallco Park Area (page 3-12) : The comments in our Report remain unchanged. o Summary (page 3-12) : 1 . Our statement that construction cf Route 85 , as an expressway or freeway from Stevens Creek Boulevard southward to Highway 101 , would not be in the best interests of Cupertino remains unchanged. Based on our re-assessment of the applicability of the CAPSSI method, we believe that DeAnza as an eight-lane arterial and Stelling as a four-lane roadway could adequately serve through 1990 (with represents build-out cf Cupertino according to the existing General Plan) without a new roadway in the Route 85 Corridor. If the intensity of future development is increased, the need for the new Route 85 roadway as a through facility from . Mr. Dick Childress , Chairman Page 5 July 13 , 1982 F15741.A0 . 00 Stevens Creek to Prospect would also increase. It is not clear at this time exactly when the need would become acute enough to initiate a new Route 85 roadway, since it will depend on future travel times, delays , improvements , and level of development along DeAnza, Stelling, Bubb, McClellan, Rainbow, Prospect, and other roadways in the area. Our comments expressing concern with the method of calculating future levels of service are largely superseded by the discussion earlier in this addendum. We still caution that factoring up existing intersection conditions to future, higher volumes may produce misleading results in certain instances. Although the need may not be as pressing as earlier thought, the retention of the existing Route 85 right-of-way from Stevens Creek to Prospect still appears to be in the best interests of long-range planning for the community. 2 In line with the above comment, we believe that development of a plan for a new roadway in the Route 85 corridor is appropriate a part of a citywide street Master Plan. By retaining the right-of-way and establishing a plan for the roadway, City the can preserve the option of having all or part of the facility at any time in the future. If Cupertino reaches full development without needing the planned roadway, the Master Plan may be changed and the Route 85 right-of-way used for other purposes. 3. We stand with our recommendation that Stelling be improved to a continuous, four-lane roadway with adequate intersection improvements from Stevens Creek to Rainbow. Local traffic and some through traffic will continue to use the street. Without the improvements, Stelling will continue to experience long queues and considerable congestion at intersections . With the improvements, traffic would flow smoothly on the street. 4. Our comments regarding scheduling of DeAnza College classes and other major traffic generators remain unchanged. Mr. Dick Childress, Chairman Page 6 July 13, 1982 F15741.A0. 00 5. We continue to believe that DeAnza should be utilized as the major north-south arterial corridor through Cupertino. The interconnected signal system will improve the street' s operating conditions (primarily by reducing delays to the major movements) , while a grade separation at Stevens Creek and DeAnza may not be cost effective. As an eight-lane roadway, DeAnza will accommodate most of the existing General Plan traffic. Some traffic, although a smaller amount than previously thought, will spill over to Stelling, Bubb, etc. as travel times balance. The combination of these roadways would accommodate General Plan traffic at LOS D or better during peak hours without a new roadway in the Route 85 corridor. A Route 85 roadway may be desirable to reduce through-traffic on Stelling and Bubb if Cupertino develops at increased land use intensities. 6. , 7. , and 8. Our comments remain unchanged. In conclusion, our re-evaluation of the part of the City' s Traffic Study regarding intersection capacity analysis indi- cates that most of the City' s findings and recommendations are realistic, in view of the acceptability of higher delay ranges to motorists in Cupertino. Without the computerized ability to perform systemwide iterations, balancing operating con- ditions on DeAnza with travel times on less direct routes, we are unable to predict the impacts to all of the roadways under various scenarios of increased development intensities. Because of uncertainties in the ultimate development levels and in the ability to precisely determine traffic conditions throughout the network, we encourage the Subcommittee to view Cupertino ' s transportation network as a complete system. The Master Plan for the transportation system should provide sufficient capacity and flexibility to permit adjustments that may be required by unforseen changes in the future. S . Richard Luebbers, P.E. fo SFR39/001 I I corridor basis. Individual streets may function differently due to the location of freeway ramps or unique roadway configurations. INEED FOR A POSTCARD SURVEY The question of whether or not additional verification of I the City' s modeling process is needed to provide better validation has been raised . One way of obtaining additional data would be to conduct a postcard survey of drivers on U Cupertino streets. A weakness of the type of license plate survey that was I conducted is that many assumptions must be made regarding the origin and destination of trips crossing Stevens Creek Boulevard. These assumptions tend to reduce the confidence level of the survey results. A postcard survey could be I designed to determine the origin, destination, and purpose of trips crossing the screenline or passing through other survey points . Assuming that a statistically significant I return of postcards can be obtained, such a survey would add confidence to the use of the City model . postcard survey also has faults. One that is often suggested IA is that there is a possibility of a biased return, because certain segments of the drivers sampled may return the cards at a higher rate than other segments. For example, Cupertino I residents may have a higher rate of return than nonresidents. The cost of a postcard survey depends on the number of I postcards distributed and returned, the type and amounts of data to be processed, and the number of survey locations selected. Assuming a five-station survey, 3 hours in dura- tion, the following number of person-hours has been estimated: 1 Traffic Control 20 person-hours Training/Survey 200 person-hours IIData Processing 160 person-hours SENSITIVITY ANALYSIS IAt its current level of sophistication, the City model will provide general data on future traffic movement throughout the City. Overall estimates of the amount of through traffic can be estimated. Also, estimates of the amount of through trips that can be diverted from existing City streets by construction of a facility in the Route 85 corridor can be Imade with some limited degree of confidence. We believe that the City traffic projection technique, as 1 used to date, is appropriate for coorridor and screenline types of evaluations. However, the results of "factoring-up" existing street volumes, based on projected increases in traffic across screenlines, should be supplemented with I 2-8 11 I I other intersection data ( i.e . , current actual counts ) when designing specific intersection improvements. The current City procedure does not take into account localized condi- ' tions or traffic impacts that result from new or expanded developments on a specific site; however, the City' s ongoing technique of analyzing a range of traffic estimates makes I the procedure more acceptable . SUMMARY li 111 This review of the Cupertino traffic model indicates that the techniques used by the City are generally val id for the level of transportation planning sophistication that was I originally desired. In some cases, additional verification of data is suggested which, assuming positive results, will further verify the techniques being used. Listed below are I recommendations for tasks that will strengthen the continuing City modeling procedure. 1. The latest traffic data from the County model should be I used for future City model runs, especially as updates and changes occur in the County model . ' 2. Continue to develop a computer-assisted traffic assign- ment technique, as this tool will provide faster, more consistent results and will enable the City to compare alternative street networks and/or land use alternatives I with more confidence. Data from this type of assignment will be more suitable for design purposes than the current City techniques I3 . It is our opinion that a postcard survey is not necessary at this time, and in fact may produce confusing results I because of potential bias from the survey. I I I I I I II 2-9 II I , ' IHI Chapter 3 MO REVIEW OF CITY RECOMMENDATIONS This chapter describes our review of recommendations made by City staff concerning four key areas within Cupertino. Our ' review was based on results of the County and City traffic projections, the license plate survey conducted by the West Cupertino Homeowners Association, discussions with City Staff and the Transportation Sub-Committee, and our own analyses and field reconnaissance of the City. ' The following four areas were evaluated: 1. The Route 85 extension 2. West Cupertino Neighborhood area 3. Stevens Creek Road/De Anza intersection 4. Vallco Park area ADDITIONAL COUNTY DATA At 'the request of the Consultant, MTC and the County per- formed a computer run specifically for the Cupertino area. This data was requested in order to conduct an in-depth evaluation of the recommendations made by the City staff and as an additional method of checking the City's traffic study ' for the Cupertino area. The data, prepared in January 1982, consisted of the distribution table from the latest County model for 1990 a.m. peak hour trips, by traffic analysis zone, produced and attracted to Superzone 10. The additional data was obtained following initial review ' and general approval of City modeling techniques, and pro- vided for a more in-depth and independent check of the City model . Superzone 10 consists of 19 traffic analysis zones. County projections of trips to and from each of these zones ' were used in various ways to evaluate the City model . The data was used to perform a more detailed analysis of ' projected 1990 trip movements in the Cupertino area. Using this data and projected traffic volumes from the County' s trip assignments, the number of trips that would pass through ' Superzone 10 (external trips ) was calculated. The external trips were analyzed at each of four screenline boundaries around Superzone 10 to determine the volume of external trips on major roadways crossing the screenlines. From this S data, the number of a.m. trips that would cross Cupertino in the northbound direction was calculated . ' Analysis of the data produced in this evaluation was used in subsequent analyses discussed later in this section. This data includes projected numbers of through trips for major arterials within Cupertino. ' 3-1 IA further byproduct of this evaluation was the substantiation of the City's determination that approximately 20 to 25 per- cent of the total traffic within Cupertino is through traffic . ' This analysis indicates that through traffic amounts to 22 percent. However, it should be noted that this percentage only represents through trips passing one point (a screenline at Stevens Creek Boulevard) , and that the percentage of through trips on any one street can vary, as can the percent- age of through trips at different points along the same Istreet. The data produced by the County and MTC in January 1982, although provided part way through the study, was very I helpful in evaluating the validity and currency of the City' s modeling process. It should be used as a base for continuing work by the City. IROUTE 85 EXTENSION The West Cupertino Homeowners Association conducted a license II plate origin-destination survey in 1981 to determine the amount of through traffic using West Cupertino streets, such as Stelling, Bubb, McClellan, and Rainbow. IThe two-hour survey results indicated that: ( 1 ) 32 percent of the vehicles turning left from Stevens Creek Boulevard to I Bubb Road were also observed leaving the neighborhood at McClellan, Rainbow, or Prospect ( 470 of 1, 470 vehicles) ; and ( 2) 44 percent of the vehicles turning right from Stevens Creek Road to Stelling were also observed leaving the neighbor- Ihood at McClellan, Rainbow, or Prospect ( 669 of 1,521 vehicles) . If Route 85 were extended southerly from its present terminus I at Stevens Creek Boulevard to at least De Anza Boulevard, some of these through trips would be diverted to the new facility. The amount of diversion would depend on the type II of facility constructed. If the facility included at-grade intersections at some cross streets ( for example, at McClellan and Stelling) , trips observed leaving the neighborhood at McClellan would use the new Route 85 facility. However, if I Route 85 is extended to De Anza Boulevard as a freeway with no interchanges between Stevens Creek and De Anza, some of those trips now oriented to McClellan would probably not be I diverted to the new facility since many of these trips may be destined for southeastern Cupertino. I Arterial Street Extension of Route 85 to Prospect For this analysis, it was assumed that Route 85 would be extended to Prospect Road as a 4-lane arterial street, with I at-grade intersections at McClellan, Stelling, De Anza, and Prospect. Access at other points ( if any) would be located at public streets and would allow for right turns on and off I of Route 85. Direct access to private property would not be allowed. 3-2 II II II It would appear that all of those trips exiting the neighbor- hood at Rainbow and Prospect would use the Route 85 extension Ito either De Anza or Prospect. It also appears that those trips exiting the neighborhood at McClellan would use only the northerly portion of the Route 85 extension. ICurrent traffic volume counts ( from City files) indicate that about 55 percent of the 4 : 30 to 6 : 30 traffic would be I included in the p.m. peak hour . Therefore the following diversions can be assumed (p.m. peak hour vehicles) . The volumes shown below were calculated by multiplying the 4 : 30 to 6 :30 volumes from the homeowners survey by 0.55. The Inumbers in parentheses are from the homeowners survey. 1. Vehicles diverted from Bubb, Rainbow, Stelling I and/or Prospect to Route 85 between Stevens Creek and De Anza or Prospect ( 29+250 ) X 0. 55 = 154 2. Vehicles diverted from Bubb and McClellan I to Route 85 between Stevens Creek and McClellan ( 191) X 0.55 = 105 I 3 . Vehicles diverted from Stelling and Prospect to Route 85 between Stevens Creek and De Anza or Prospect ( 46+319 ) X 0.55 = 200 I4. Vehicles diverted from Stelling to Route 85 between Stevens Creek and McClellan ( 304 ) X 0.55 = 167 IIFigure 2 indicates the estimated increases and decreases in 1981 p.m. peak hour volumes that could be expected if an I arterial street were present in the Route 85 corridor. The level of change in future ( 1990) traffic voulmes is also shown in Figure 2, assuming a 30 percent increase in traffic II volumes by 1990. One element of traffic diversion that is not shown in Figure 2 is the traffic that now uses Stevens Creek and De Anza I Boulevards. Some of these trips would also be diverted to Route 85. Some of the trips would be through trips and some would be trips destined for southeastern Cupertino neighbor- Ihoods. Freeway Extension of Route 85 to Prospect I For this scenario, it was assumed that Route 85 would be extended as a four-lane freeway to De Anza or Prospect with interchanges at Stevens Creek Road, De Anza and Prospect. IIn this case, some of the trips now on Bubb and Stelling that were observed to exit the neighborhood at McClellan I would probably not be diverted to the Route 85 extension as this route would take them too far south to provide a travel I 3-3 I 1 -367 II ( -484 ' STEVENS CREEK BLVD . 4 I t I Cr, N I I If) .1 k62t 4om N In43?-61 rh d i I I + 167 ( +220 ) McCLELLAN ROAD 1 I - 138 ( - 138 ) ��O % am' o <\ o ko I ` �S NN I I 0 L I1 0 CC l" , J m m Q I r., coz coz Q W h ,1 t� I .11 . x" �6 x O � d _ o %0 , U in O NN , — N I I I I % • IS RAINBOW DRIVE • I -154 \ -41 ( -203 ) p ( -54 ) ; Q % 0 I 0 _ � z M rh M M __ r7 d I P„ _ + + 1 I w I—L LEGEND PROSPECT ROAD - 154 : 1980 - CHANGE IN PEAK I (-203 ) : 1990 HOUR VOLUMES FIGURE 2 ICHANGE IN TRAFFIC VOLUMES WITH ROUTE 85 EXPRESSWAY EXTENSIOHILL IF 15740A0.00 I time advantage . For this evaluation, it was assumed that one-half of the McClellan oriented trips would be diverted I to the Route 85 extension and then would exit at De Anza and travel north to their destination. Diverted trips described under Items 1 and 3 for the express- way, scenario would also be diverted at the same level under this scenario; however, the McClellan trips diverted (Items 2 and 4 ) would be one-half the previous values. ill I Figure 3 shows p.m. peak hour volume changes for current and projected 1990 conditions. Again, there would also be some I current trips diverted from the Stevens Creek/De Anza route to the Route 85 extension. Route 85 Freeway Extension to Route 101 IThe current county roadway plan includes the extension of Route 85, as a six-lane freeway, from Stevens Creek Boulevard I to Route 101 in South San Jose. The most recent Santa Clara County traffic model was used by the County to test this alternative as well as a four-lane expressway between Stevens I Creek and De Anza, and a four-lane expressway between Stevens Creek and Route 101 (South San Jose) . Table 1 shows the resulting a.m. peak northbound volumes at three screenlines in the Cupertino area, taken from results of the County I model . At the Stevens Creek Boulevard and Prospect/Lawrence Express- ' way screenlines, about 4,000 to 4, 200 more total vehicles were assigned by the model assigned with a six-lane freeway (Stevens Creek to Route 101, South San Jose) than with a 1 I four-lane expressway between Stevens Creek and De Anza. This data indicates that a full freeway facility would draw approximately 4 ,000 more through trips into Cupertino than a short four-lane expressway. It appears that some of the I increased through trips would be diverted from other facil- ities that do not penetrate Cupertino, such as Route 101. It also appears that most, but not all , of these 4 , 000 I diverted trips would stay on the Route 85 freeway through Cupertino. Detailed data from the County model indicated that higher I a.m. peak traffic loads could be expected on Bubb, Stelling, De Anza , and Blaney with the six-lane freeway than with the 1 short (to De Anza or Prospect) four-lane expressway. One II reason for this may be that traffic conditions on the Route 85 freeway would be relatively free-flowing from Route 101 (South San Jose) to near Cupertino. At that point the ' assignments indicate that congested conditions in the Route 85/ I-280 area would slow traffic to where the Cupertino arterial streets would appear more attractive than Route 85 in terms of travel time . I 3-4 I -206 , -284 I ( -272 ) ` ( -375 ) STEVENS CREEK BLVC . �D N CO r O N e N fn I N N , 9C I x�xb 1-`11 l V I % -52 ( -69 ) - 136 MCCLELLAN ROAD ( - 180 ) - 52 I (-69 ) I .. r G� O a , <\ ono I NI Ni ;5 I x 0,913 o I Q S > , CDCOCC 141 �O O Q I co co % th W N Z + + Q m lbW Is^ • .t fn Od ,, In O O q) , I N I 1 N N , O x 1.*9 u, , xb IS RAINBOW DRIVE • - 154 I ( -203 ) Q ( - 4- 1 ; 54 o • cc • I M M v M fn , N I-I z .r 0-1I M .7 fn .7 I I -J + .} I v -1 111 i— (/) ILEGEND PROSPECT ROAD -313 : 1980 - CHANGE IN PEAK ( -413 ) : 1990 HOUR VOLUMES I FIGURE 3 I CHANGE IN TRAFFIC VOLUMES WITH ROUTE 85 FREEWAY EXTENSION 2Ift I F 15740.A0.00 1 1 Table 1 SCREENLINE COMPARISONS HOMESTEAD SCREENLINE--A.M. PEAK, NORTHBOUND Total Facility Type and Limtits Volume 1 6 Lane Freeway to Route 101 (S . San Jose) 23, 555 4 Lane Expressway to Route 101 (S. San Jose) 21, 979 4 Lane Expressway to De Anza 19 ,893 STEVENS CREEK SCREENLINE--A.M. PEAK, NORTHBOUND 1 Total Facility Type and Limits Volume 6 Lane Freeway to Route 101 (S . San Jose ) 15, 306 ' 4 Lane Expressway to Route 101 (S. San Jose) 12, 183 4 Lane Expressway to De Anza 11, 1071 No Facility--Existing ( 1980 ) Volumes 10, 330 1 PROSPECT/LAWRENCE SCREENLINE--A.M. PEAK, NORTHBOUND 1 Facility Type and Limits TotalVolume 1 6 Lane Freeway to Route 101 (S . San Jose ) 11, 004 4 Lane Expressway to Route 101 (S. San Jose) 8, 037 4 Lane Expressway to De Anza 7, 039 1 Source : All values, except those noted below are from the 1 County model . 1From City files. i i 1 i 1 3-5 ' Summary II The above analysis indicates that a six-lane freeway exten- sion to Route 101 would draw about 4, 000 more northbound a.m. peak trips through Cupertino than a four-lane express- ' way to De Anza or Prospect. Most of these 4,000 trips would stay on the Route 85 freeway through Cupertino. Some would be diverted to Stelling, Bubb, and other Cupertino streets. It is assumed that p.m. peak conditions would be similar, ' but reversed in direction. The analysis also indicates that 400 to 700 current and 500 ' to 900 future trips could be diverted from West Cupertino arterial streets if either a freeway or an arterial street is constructed in the Route 85 alignment. The County assignment of 1990 northbound traffic for a ' four-lane expressway to De Anza indicated hourly volumes of 2, 000 to 3, 000 vehicles at various points. A four-lane ' arterial street with left-turn lanes at intersections has a capacity level of approximately 2,000 vehicles per hour ( for planning purposes) . Therefore, this type of facility may ' not have sufficient capacity to handle assigned volumes at all intersections. The p.m. peak hour volumes at Stevens Creek may be high enough in 1990 to warrant a grade separa- tion facility. However, the County assigned volumes on some existing arterial streets, such as De Anza, were lower than the existing capacity of these facilities . It is likely that actual 1990 traffic volumes would be distributed so II that the Highway 85 volume would be near the 2, 000 capacity figure. ' NEED FOR ROUTE 85 EXTENSION The above discussions described the amount of through traffic that could be diverted from West Cupertino streets to a new roadway in the Route 85 corridor, and indicated the probable traffic volumes that would occur on the new facility. However, the need for the new roadway, and the type of ' facility to be provided, need further clarification. Clearly, the data indicates that a new roadway ( four-lane ' expressway or six-lane freeway) from Stevens Creek to High- way 101 in South San Jose would attract a substantial number of trips through Cupertino. These trips would be diverted from highways that do not pass through Cupertino. The ' traffic would be of no benefit to Cupertino businesses or residents. In fact, a major expressway or freeway would add traffic to Cupertino streets at certain times of the day and would increase noise levels and air pollution emissions in the City. From Cupertino's perspective, a new roadway in the Route 85 corridor should not extend farther south than Prospect Road. A road of this length would divert through trips now using West Cupertino streets and would provide a ' 3-6 111 convenient route for many Cupertino residents without attract- ing large numbers of outside trips. ' The City's traffic report recommended that the Route 85 right-of-way in Cupertino be abandoned for use as a major ' roadway corridor, essentially restricting forever the exten- sion of Route 85 as a high capacity roadway. The report further recommended that the 200-foot wide right-of-way be made available for residential development, along with which a new two-lane, local roadway would be constructed at no cost to the City. The new local roadway would be connected to the existing street system to serve the surrounding ' neighborhoods, De Anza College, and the West Valley Indus- trial Park. The City' s report recommended that increases in traffic be ' accommodated by improvements to existing roadways, primarily De Anza Boulevard. The potential improvements included a grade separation facility at Stevens Creek and De Anza, a permanent facility for the terminus of Route 85 at Stevens Creek, two new lanes on I-280, and completion of the traffic signal interconnection system on De Anza. 11 The primary objective of the City's recommended plan was to utilize De Anza Boulevard, to the maximum extent possible, as the major carrier of traffic (particularly through traffic) in Cupertino. Through trips on other City streets would be discouraged, even to the extent of severing Stelling north of Prospect. ' The City staff determined the future operating conditions using a technique called Comprehensive Analysis Program for ' Single Signalized Intersections (CAPSSI) that apparently is being used by some communities in Southern California. The technique considers the layout of the intersection, the volume of traffic on each through and turning movement at the intersection, the traffic signal operation, the presence of pedestrians and other localized conditions. The method apparently also requires measurement of existing traffic to determine the maximum flow rate that local drivers routinely achieve . This "saturation flow rate" is used in calculations of the capacity and the expected level of service provided by the intersection for the given traffic movements. Level I of service (LOS) is a term used to define the operating conditions experienced by drivers using the intersection. The levels are divided into categories from A to F, with A representing unimpeded flow and F indicating complete failure. Level of Service E is generally considered to be the capacity of the intersection. The City staff chose LOS D for 1990 design conditions. Complete descriptions of the operating conditions associated with each level of service are more fully described in Table 2. ' 3-7 Table 2 ' LEVEL OF SERVICE (LOS) DESCRIPTIONS FOR INTERSECTIONS Level of Service A o No approach phase is fully utilized by traffic . ' o No vehicle waits longer than one red indication. o Nearly all drivers find freedom of operation. ' Level of Service B o An occasional approach phase is fully utilized. o Many drivers begin to feel somewhat restricted within platoons of vehicles. Level of Service C o Intermittently approach phases are fully utilized. o Occasionally drivers may have to wait through more than one red signal indication. o Backups may develop behind turning vehicles where a separate signal indication is not provided. ' o Most drivers feel somewhat restricted but not objectionably so. Level of Service D o Delays to approaching vehicles may be substantial during short peaks within the peak period but ' enough cycles with lower demand occur to permit periodic clearance of developing queues. Level of Service E o Capacity or the probable maximum number of vehicles that any particular intersection approach can ' accommodate . o Long lines of waiting vehicles upstream of the intersection may develop. ' o Delays may be great with some vehicles waiting through several signal cycles. Level of Service F o Forced flow. o Backups from locations downstream or from cross streets restrict approach operation. ' 3-8 r 11 ICity staff used the overall projection of traffic growth in Cupertino obtained in the earlier part of the study to II determine the approximate amount of growth that might be expected along the principal corridors in the City. They determined that traffic was likely to increase about 32 per- ' cent on major streets near Stevens Creek with gradually smaller amounts on either side of Stevens Creek, to as low as 2 percent at De Anza and Prospect. The existing through and turning movements were measured and then extrapolated to I 1990 volumes using the assigned growth factor. The CAPSSI technique was used to estimate future operating conditions at key intersections. The recommendations for improvements I in the Route 85 corridor, De Anza Boulevard, and other streets were based on the need to maintain LOS D or better operating conditions. IICH2M HILL normally uses the Critical Movement Analysis of capacity calculation published by the Transportation Research Board (TRB) in Circular 212, entitled "Interim Materials on ' Highway Capacity. " This method was developed under a National Cooperative Highway Research Program and is being widely used by traffic agencies across the United States. IIWe utilized the TRB capacity technique to attempt to verify the calculations made by City staff. We used the information provided in Exhibit B of the City' s Summary Report and IIinformation provided by City staff that was used directly in their calculations. The estimated future operating condi- tions were found to be far worse than the City report indi- ' cated. De Anza, for instance, was calculated to be at LOS E or F from Bollinger Road to as far north as I-280. Indica- tions were that approximately 500 vehicles would have to be I diverted from De Anza to other facilities. Since other major north-south roadways, such as Stelling and Wolfe, were projected to also be approaching capacity, it was our opinion IIthat a new four-lane arterial roadway in the Route 85 corridor was needed to relieve De Anza. Stelling and Bubb would also be relieved by the new roadway. In total some 1, 100 to 1,200 vehicles that would otherwise use De Anza or West II Cupertino roadways would be diverted to the new roadway, as would an undetermined number of Cupertino residents who chose to use the new route. These figures were based on the II traffic volumes associated with the General Plan. If an increased intensity in future development occurred, the number of vehicles diverted to the new Route 85 roadway would be increased. Major improvements at the Stevens ' Creek-De Anza intersection (either addition of a significant number of traffic lanes or construction of a grade separation facility) would also be necessary. ' These conclusions were presented to City staff and the Transportation Sub-Committee. The large differences were discussed, along with their ramifications. The staff, during and subsequent to the meeting, provided additional 1 II I 3-9 information on the CAPSSI technique and their application of ' it. One of the major differences between the two methods appears to be in the volume of traffic that is considered to be the maxium that a traffic lane can accommodate; i.e. , the capacity. The TRB method utilizes a maximum volume of 1, 800 ' passenger cars per hour for a standard traffic lane based on a large number of studies nationwide. Adjustments are made to account for nonstandard lane width, traffic conditions, and the like . The CAPSSI method requires that the saturation flow rate (capacity) be determined locally for each type of roadway and each type of intersection movement. City staff indicated that the capacity of a standard traffic lane on major roadways in Cupertino was found to be 1,950 vehicles per hour based on data gathered by onsite studies of existing traffic operations. Although no supporting information was provided by the City to substantiate their 1, 950 vehicle per hour capacity and I without independent field studies to verify the number, we consented to perform additional capacity calculations . We started with the assumption that a capacity of 1,950 vehicles per hour was a realistic representation of actual traffic characteristics in Cupertino. We then attempted to modify the basic TRB capacity analysis procedure by incorporating a maximum single lane capacity of 1 ,950 vehicles per hour in place of the original 1, 800. Some obvious adjustments were made, but it was impossible to determine the effect on all of the many factors involved without a thorough investigation. The modified TRB method was used to estimate future traffic operating conditions at critical intersections. This analysis indicated that De Anza, as a six-lane facility, would be ' operating at LOS E or worse at most major intersections from I-280 to Bollinger. Addition of a fourth traffic lane in each direction for that length of roadway would apparently ' improve operating conditions to LOS D for most intersections. Additional improvements would be required at Stevens Creek and De Anza to accommodate left and right turns. A grade separation at the intersection would probably not be worth the money, since four lanes would have to be maintained in both directions on De Anza to provide continuity in the roadway cross-section. The grade separation would also tend to dissipate platoons of vehicles advancing through the interconnected signal system, thereby tending to disrupt the overall operation of the street. ' If Cupertino develops at an increased intensity and the traffic volumes increased accordingly, then De Anza would be unable to accommodate the high flows, even as an eight-lane ' roadway. A new four-lane arterial would be required in the Route 85 corridor and a grade separation or substantial intersection improvements would be required at Stevens Creek ' and De Anza. ' 3-10 11 STELLING ROAD City staff recommended in their report that Stelling Road be modified to handle only local traffic. It was intended that the proposed, new, two-lane roadway in the Route 85 corridor ' would accommodate some of the future local traffic growth, and another 600 vehicles in the peak hour would be shifted to De Anza. It was suggested that Stelling be closed at Prospect Road and that Bollinger Road be extended westward to Stelling. Our original analysis using the standard TRB methodology, ' indicated that traffic could not be diverted from Stelling to De Anza since De Anza would be over capacity. The sugges- tion that the proposed two-lane roadway would help reduce traffic levels on Stelling appeared to make little sense ' since the proposed roadway was to be essentially local in nature . Any traffic diverted from Stelling would probably be local traffic, not through traffic. Furthermore, if ' Bollinger were extended westward to Stelling, a significant number of new through trips would be attracted to the upper part of Stelling, since De Anza would have adequate capacity ' south of Bollinger, making the route quite attractive to southbound through trips. Closure of Stelling at Prospect would do little to help local traffic circulation but would add traffic to McClellan, Bollinger ( if extended) , and ' Rainbow, without reducing traffic on most of Stelling. Our analysis using the modified TRB method indicated essen- tially the same conditions for Stelling as described above since De Anza, even if improved to eight lanes, would not be able to accommodate additional traffic north of Bollinger. It appears that Stelling would have to be retained as an arterial facility to accommodate some through traffic as well as existing and future local traffic under the City' s proposed plan. Improvement to a continuous four-lane road- way with appropriate left- and right-turn lanes at least as far south as Rainbow, and perhaps all the way to De Anza (via Prospect) would be necessary to ensure an adequate I level of service. Bubb, McClellan, Rainbow and others would probably also require improvement to accommodate the continued flow of through traffic under General Plan conditions. Additional improvements may be required to roadways in West Cupertino if an increased intensity of development occurs in the area. DE ANZA BOULEVARD ' The probable future conditions on De Anza Boulevard were discussed along with Route 85 above. The improvements at Homestead and at I-280 described in the City's report will be necessary. Our analysis indicates that a grade separation at Stevens Creek and De Anza may not be as attractive as 3-11 earlier thought by the City, primarily due to limitations in the capacity of nearby intersections on De Anza. A grade ' separation may be desirable, however, to emphasize the availability of De Anza as a major through route. ' The traffic signal interconnection system, when fully operable, will aid through traffic flows on De Anza. It will not cause the street to operate like a free-flowing expressway, and it will not shorten the length of time vehicles on ' side-streets or in left-turn bays will have to wait for a green light. ' Finally, the City' s statement that De Anza will be capable of handling traffic growth plus diversions from Stelling does not appear to be accurate. Our analysis indicates that De Anza must be widened to eight lanes from I-280 to Bollinger to accommodate traffic growth in the corridor and still remain at LOS D. Stelling and Bubb will have to continue to carry a significant amount of through traffic . ' VALLCO PARK AREA ' It is our understanding that the decision to lift the develop- ment restrictions previously established for Vallco Park ( in 1973) has been recommended by the City Department of Public ' Works and is currently being considered by City Council . We have reviewed the traffic report prepared to evaluate full development of Vallco Park. The report appears to be compre- hensive, conforms to current analysis techniques, and appar- ently agrees quite well with analyses prepared by City staff. The traffic impact report evaluates 1990 level of service at six intersections adjacent to Vallco Park, and includes mitigation measures that are designed to achieve a level of service D or better. Our scope of work does not allow for a detailed review of the traffic impact report; ' however, it appears to have been prepared by professionals using standard traffic impact assessment techniques . SUMMARY ' Our review of the City staff' s Recommended Implementation Plan leads us to the following conclusions ( listed in the ' same order as the City' s recommendations on Page 6 of their Phase III report) : 1. Construction of an expressway or freeway in the Route 85 ' corridor from its current terminus at Stevens Creek Boulevard to its planned connection with Highway 101 in South San Jose would not be in the best interests of ' Cupertino. The facility would serve some local residents and would divert some through trips from local streets at certain times of the day, but at peak hours would ' attract a large number of outside trips through Cupertino. The through trips would add noise and air pollution as 3-12 I Ithey passedthrough throw h the corridor and would divert to local streets whenever a significant amount of conges- 1 tion occurred on the new roadway. The City's report recommended that a new two-lane I roadway designed to serve local traffic be constructed in the Route 85 corridor and the rest of the 200-foot right-of-way be developed with housing or other facil- ' ities. Their capacity analysis indicated that addition of one additional traffic lane in each direction on De Anza between I-280 and Bollinger and improvement of portions of Stelling would provide sufficient capacity I to accommodate through traffic to 1990, which is intended to represent buildout of Cupertino and most of the County around it. ' Our analysis using the standard Transportation Research Board methodology indicated that De Anza would not be II able to accommodate traffic at LOS D through 1990, even as an eight-lane facility. After we modified the TRB method to incorporate the higher flow rates utilized by the City, our analysis indicated that traffic growth II could be accommodated by providing eight lanes on De Anza from I-280 to Bollinger and by improving Stelling to a continuous four-lane arterial at least as far I south as Rainbow. With these improvements, a new roadway in the Route 85 corridor to accommodate through traffic would not be required prior to 1990. I While we must concur that our analysis using the modified TRB method provided essentially the same results as the City's analysis using the CAPSSI method, we must also point out several concerns that we have about the overall methodology. First, we were not provided with information that would enable us to evaluate the satura- tion flow rate of 1 ,950 vehicles per hour used by the ' City. Second, although we made adjustments in the TRB method in an attempt to reflect the higher flow rate ( 1, 950 vs. 1, 800 ) we cannot be sure without additional ' study that the adjustments were entirely appropriate. Third, the calculations in the capacity analyses were performed using data that was obtained by factoring up existing conditions at critical intersections with little patterns and to future changes in traffic or consistency with earlier portions of the study process . II Finally, the results of the analysis indicated that De Anza (as an eight-lane facility) and most of the other major north-south streets in Cupertino would be operating at or near LOS D at some, if not most, of I their major intersections by 1990 to accommodate traffic associated with growth according to the current general plans of Cupertino and surrounding cities. If future I development occurs at increased intensities, the City's recommended street network would be unable to accommodate 3-13 I r 1 II the additional traffic without rovisions for more P carrying capacity. If the Route 85 corridor had been IIabandoned as a major roadway in lieu of residential development with a local street, it is uncertain how the additional capacity would be obtained. II In our opinion, the Route 85 corridor should not be abandoned, but should be retained with sufficient right-of-way for construction of an arterial roadway I from Stevens Creek to Prospect. 2. Development of a master plan for the Route 85 corridor, I including a future, limited access, four-lane roadway from Stevens Creek to Prospect; with at-grade intersec- tions at Stevens Creek, McClellan, Stelling, De Anza, and Prospect is encouraged. Maintain sufficient right- ' of-way to construct long range future grade separations at some of the intersections, particularly Stevens Creek and De Anza. I3 . It appears to be unlikely that all of the through traffic on Stelling would be diverted under the City' s recommended plan of utilizing De Anza as the only major north-south arterial in Cupertino, unless the proposed two-lane roadway in the corridor was designed to be primarily arterial rather than local in nature. In I either case, it appears that Stelling should be retained as an arterial route and should be improved to provide a continuous four-lane section at least as far south as I Rainbow. If significant improvements were made to De Anza and the new roadway in the Route 85 corridor were built II with good through traffic characteristics , then the improvements to Stelling would provide an excellent facility for existing and future local traffic . If the I new Route 85 roadway was primarily local in nature or was not built at all , and De Anza was not adequate to handle all of the traffic (either because all required I improvements were not made or traffic growth was greater than anticipated) , then the additional capacity would be required on Stelling to accept part of the overflow. II4. Continued work with De Anza College in scheduling classes at nonpeak traffic times is encouraged. Similar efforts are also encouraged with all major employers in I Cupertino. 5 . The recommendation that De Anza be continued as a major I north-south arterial corridor through Cupertino is appropriate . Addition of one through lane in each direction between I-280 and , along Bollinger, with 9 additional at-grade improvements at Stevens Creek and I De Anza, will be required to accommodate General Plan 1 3-14 i I _ J r II Itraffic. The interconnected traffic signal system should be completed and adjusted to provide optimum I traffic flow on De Anza. A grade separation at Stevens Creek and De Anza probably would not provide sufficient additional capacity to the corridor to justify the capital expenditure. IIIt should be noted that the expansion of De Anza to an eight-lane roadway, without an arterial roadway in the I Route 85 corridor to accommodate through traffic, would not provide adequate capacity to accommodate all north- south traffic growth generated by the future City' s I General Plan. Stelling, Bubb, Wolfe, and other existing north-south streets, as well as some east-west streets, would continue to carry significant amounts of through traffic . If an increased level of intensity occurs in I future development in and around Cupertino, it is likely that De Anza, and most other north-south streets, would have operating conditions at or below LOS E at I critical intersections. 6 .- The decision to release Vallco Park' s uncommitted lands for development should be made in conformance with I overall goals for Cupertino, using the recent Traffic Impact Report ( 1981) as a reference for traffic aspects. II 7. It is our understanding that removal of the 16 trip end constraint on De Anza and Stevens Creek was included in the General Plan and therefore in the traffic numbers analyzed. It would appear that lifting of the constraint I would be appropriate if roadway improvements are made as discussed earlier . II 8 . The development of a capital improvements program for the Cupertino roadway network along with a funding mechanism based on state, local , and developer contribu- ' tions is appropriate. II II II II II 3-15 l J ■■ Appendix A OHO LIST OF DATA SOURCES MTC-ABAG: Santa Clara Valley Corridor Evaluation Final Environmental Impact Report. October 1979 . Santa Clara Valley Corridor Evaluation Public Participation Final Report. March 1979 . ' MTC: Pat Hackett, Guadalupe Corridor Computer Runs. Select Zone Run Santa Clara County: Guadalupe Corridor Phase II Alternatives Analysis/D.E. I .S. Travel Model Assumptions, Volume I. September 1980. Guadalupe Corridor Phase II ' Alternatives Analysis/D.E.I.S. Travel Model Assumptions, Volume II . September 1980. • Guadalupe Corridor Computer Assignment Run. October 1981. ' Jim Pierson; Transportation Engineer. County Computer Model . 1 City of Cupertino: General Plan Transportation Element. Phase I, II, III, and Summary. May, June, September, ' and December 1980. Land Use Element. ' Traffic Counts. 1971, 1974, 1975, 1979, 1980, 1981 . Various Intersections in Cupertino. Conversations and meetings with the Transportation Sub-committee, Bert Viskovich, and Glenn Grigg. Traffic Impact Report. Vallco Park, 1981 . 1 1 L _