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HomeMy WebLinkAboutItem 8.1 AVB/StarwardTrffcStdy (2) AGENDA STATEMENT CITY COUNCIL MEETING DATE: May 4, 1999 SUBJECT: Amador Valley Boulevard / Starward Drive Traffic Safety Report Prepared by: Lee S. Thompson, Public Works Director ATTACHMENTS: 1) 2) Report from TJKM Location diagram RECOMMENDATION: ~t41 Receive report and direct Staff as appropriate FINANCIAL STATEMENT: None at this time. DESCRIPTION: The City Council recently requested that Staff conduct traffic studies at the Arnador Valley Boulevard / Starward Drive intersection in the wake of a traffic accident involving a pedestrian and also in anticipation of traffic generated by the Starward single-family housing development. TJKN~ one of the traffic engineering consulting firms under contract with the City, obtained vehicle and pedestrian volume counts and investigated the sight distance available from both the marked crosswalk on the east leg of the intersection and the unmarked crossing on the west leg. The last engineering speed sur~,ey taken at this intersection was in 1994 and indicated an 85th percentile speed of 32 mph. This survey is due to be updated in October of this year. Sight Distance Based on the Caltrans Highway Design Manual, the stopping sight distance on Amador Valley Boulevard requires a minimum of 250 feet at a speed of 35 mph, which is the posted speed limit. Sight distance to the northwest comer of Amador Valley Boulevard and Starward Drive was measured to be 265 feet from the #1 (median) lane and 305 feet from the #2 (curb) lane for the westbound direction. The sight distance measurements to the northeast comer from the #1 and #2 lanes of westbound Amador Valley Boulevard are 330 feet and 360 feet respectively. In comparison with the Caltrans standard, there is adequate stopping distance to both the northwest and northeast comers for vehicles traveling 35 mph. It is therefore not recommended that pedestrians be prohibited from crossing from the northwest corner. However, since the sight distance is greater from the northeast comer, it is further recommended that the marked crosswalk remain in place to identify the preferred crossing. COPIES TO: TJKM ITEM NO. __~ g:~agenmisc\avb&starward Traffic Signal Warrants At the time that the Starward development was reviewed by Staff, it was felt that the traffic generation would be insufficient to warrant a traffic signal at Amador Valley Boulevard and Starward Drive. The development therefore contributed a traffic impact fee toward other improvements based on the existing Downtown Traffic Impact Fee study. The cost of installing a traffic signal is estimated at $110,000 to $125,000. In response to the City Council's request, TJKM investigated three of the eleven traffic signal warrants; i.e., pedestrian volume, accident experience, and peak hour traffic volume. Pedestrian Warrant: The Caltrans D'afficMamtal specifies that a signal may be warranted if the pedestrian volume crossing the major street is 100 or more for each of any four hours OR 190 or more during any one hour. Pedestrian volume was observed during a one-hour period between 12:40 and 1:40 p.m. in order to obtain a representative mid-day volume. Pedestrian volume was also observed while taking traffic volume counts during the p.m. peak period between 4:00 p.m. and 6:00 p.m. During the mid-day period, two pedestrians crossed Amador Valley Boulevard using the marked crosswalk. During the p.m. peak period, ten pedestrians crossed Amador Valley Boulevard. Most of these pedestrians used the marked crosswalk. It is anticipated that these pedestrian volumes would be similar to those during other hours of the day and on that basis, the pedestrian volume warrant would not be met. Accident Experience: The accident experience warrant is satisfied when five or more reported accidents of types susceptible to correction by traffic signal control have occurred x~qthin a 12-month period. A review of police reports of accidents that occurred between January 1, 1997 and the present date indicate that at most, two "correctable" accidents occurred at this intersection during a 12-month period. Peak Hour Volume: The peak hour volume warrant is intended for application where traffic conditions are such that for one hour of the day, the minor street traffic suffers undue delay in entering or crossing the major street. The D'afficgYanual provides that the lower threshold volume for a minor street approaching with one lane is 100 vehicles per hour. This lower threshold of 100 vehicles per hour applies when total traffic volume on both approaches on the major street is at least 1,800 vehicles per hour. Turning movement counts were conducted from 4:00 to 6:00 p.m. on April 22ha. The peak hour occurred between 4:15 p.m and 5:15 p.m when the traffic volume on Amador Valley Boulevard was approximately 1,975. The minor street volume for the Stam, ard Drive approach during this one-hour period was 58 vehicles, and from the library driveway on the south side, 90 vehicles. On that basis, neither approach exceeded 100 vehicles per hour. It is estimated that the new 31-1ot Starward subdivision would generate approximately 12 vehicles per hour (based on Institute of Traffic Engineers trip generation rates). This estimate is "conservative" since it assumes that all the outbound vehicles would proceed south on Starward Drive. On this basis, the Starward development would not generate enough traffic to satisfy this volume warrant. TJKM recommends that this intersection be re-evaluated once the Starward development is occupied in order to determine whether Starward Drive traffic has increased significantly. Since the Starward intersection is in very close proximity to the signalized Donohue Drive intersection, it is felt that signalizing the Starward Drive intersection would negatively impact the traffic flow on Amador Valley Boulevard. Page 2 Lighted Crosswalks Some interest was expressed in the lighted or "strobing" crosswalks that have been employed by some other jurisdictions. The cost of installing a lighted crosswalk is estimated to be $14,000 to $20,000 depending on power source, the type of activation devices used, and the width of the street. There would also be an ongoing power and maintenance cost. These devices are typically used where crosswalks are unexpected or difficult to see, and where the incidence of pedestrian traffic is reasonably high. If the City Council is interested in more statistical information or in further study regarding these devices, Staffcould prepare a more detailed report for a future agenda. Recommendation Staff recommends that the City Council review the information presented and provide direction regarding any additional action to be taken. Page 3 'Transportation Consultants MEMO · .april 27, 1999 To: From: Subject: Ginger Russell City of Dublin Fax: 833-6622, 3 pages Lori Hileman via Gordon Lum ~ Amador Vaney Boulevard/Stan, ard Drive Safety Study This memo presents the results of TJKM's analysis of the above-referenced project in the City of Dublin. The pm'pose of this study is to. evaluate the adequacy of the intersection of Ama dor Valley Boulevard (AVB)/Starward Drive in terms of sight distance and to detmnfine whether a lraffic signal is w~arranted. Sight Distance Analysis TJKM's sight distance analysis of AVB/Stam,ard Drive was presented in a pr~'ious memo dated April 19, 1999. This study was prompted by a recent accident occurring in March invoMng a pedestrian being hit by a vehicle while crossing the west leg of AVB from the northwest comer. The west leg of AVB does not have a marked crosswalk, although pedestrians can legally cross at tbs location. Currently, there is a marked pedestrian crosswalk across the east leg of AVB at Sta~,ard Drh,e. Based on the Caltrans' Highway Design Manual, 4th Edition, the stopping sight distance on AV'B requires a minimum of 250 feet at a speed of 35.mph, which is the speed limit. TJKM measured sight distance in the field to determine whether it meets the Caltrarts standard for a speed of 35 mph. Sight distance to the northwest comer at Starward Drive was measured to be 265 feet fi-om the # 1 lane (inside lane) on westbound AX, qB and 305 feet from the #2 lane (curbside). The sight distance was also measured to the northeast comer at Starward Drive from the # 1 and #2 lanes on westbound AVB. These measurements are 330 feet and 360 feet, respectively. In comparing our field measurements with the Caltrans standard, there is adequate stopping sight distance from westbound AVB to both the northwest and northeast comers at Sma. rd Drive for vehicles traveling at 35 mph. As such, it was not recommended that pedestrians be prohibited to cross from the northwest corner. However, it is safer for pedestrians to cross AVB from the northeast comer than the northwest comer at Starward Drive due to greater sight distances. Therefore, the crosswalk across the east leg of the inters~tion properly identifies the preferred place to cross AX, rB. 4234 Haclonda Drive, Suite 101. Pleasan/o ePhone (925) 463-0611 ~Fa× (925) 463-369: G~oger Russell Ci.ty of DublLn April 27, 1999 Pa~e 2 Signal Warrants In order to determine whether a traffic signal 'should be installed at the intersect/on of AVB/Starward Drive, 3 of the I 1 sigrml warrants provided in Chapter 9 of-tbe Caltrans' ~affic Manual were evaluated based on current available data. The warrants were evaluated for minimum pedestrian volume (Warr~t 3), accident exper/ence (Warrant 6), and peak hour volume (Warrant I 1). Minimum Pedext~ian IZolume According to the Traffic Manual, a traffic si£mal ~my be warranted where the pedestrian volurne crossi.ng the major street (AVB) at an intersection or mid-block location during an average day is: · 100 or more for each of any four hours; or · 190 or more during any one hour. A pedestrian count at the intersection was conducted in the field on April 26, 1999 for a me-hour per/od between 12:40 p.m. and 1:40 p.m. It is assumed that th/s hour represents typical midday pedestrian volumes, as daily data is not ax-ailable for analysis. The pedestrian count indicates that only two pedestrSans crossed AVB. Both pedestrians crossing AVB used the marked crosswalk on the east leg o£ the intersection. XVkile conducting a turn count on April 22, 1999 between 4:00 p.m. and 6:00 p.m., approximately 10 pedestrians were observed crossing AVB. The ~eat majority of these pedestrians used the marked crosswalk. It is anticipated that the pedestrian volumes observed on April 22 and 26 would be sim/hr to other hours throughout the day and would not near the thresholds that warrant a signal. ,4 ccident Experience The Accident Experience Warrant is satisfied when five or more reported accidents of types susceptible to correction by u'affie sisal control have occurred within a 12-month period. A review of police, reports of accidents that occurred between January 1, 1997 and March 31, 1999 indicate that at most two "correctable" accidents occurred at AVB/Starward Drive during a 12-month period (April 1, 15~98 to March 31, 1999). Based on the Accident Experience warrant, a traffic signal is not warranted since less than five accidents that may have been prevented with a signal occurred at this ' intersection witWn a 12-month period. Peak ZIour Volume The Peak Hour Volume Warrant is intended for application where traffic conditions are such that for one hour of the day minor street traffic suffers undue delay in mtering of crossing the major street (AVB). Since the critical speed on AVB and Starward Drive is less than 40 miles per hour, the "urban" criterion was used. For Warrant 11 to be satisfied, the Manual states that: 100 vehicles per hour (vph) applies as the lower threshold volume for a minor street approaching w/th one lane. Tn.is lower threshold of 100 vph applies if the total traffic volume on both approaches on AVB is at least 1.800 vph during the peak hour. Based on previous traffic counts, it was determined that the p.m. peak h~ur experience,,q the most traffic. Therefor'e, turning movement counts were conducted on April 22, 1999 Ginger Russell City of DubI/n April 27, I999 Pa~e 3__ during the p.m peak hour period from 4:00 p.m. to 6:00 p.m. The counts indicate that the peak hour occurred between 4:15 p.m. and 5:15 p.m. when the volume on AVB was approximately 1,975. Since the traffic on AVB exceeded 1,800 during the p.m. peak hour, the Peak Hour Volume Warrant is satisfied if either minor strut approach (Stam'ard Drive or library driveway) exceeds t00 vph. The April 22, I999 counts indicate that 58 vehicles approached AVB from southbound Stanvard Drive and 90 veb/cles approached AVB fi.om the northbound library driveway duhng the p.m. peak hour. Since neither approach exceeded 100 vph, the Peak Hour Volume Warrant is not satisfieA. With the addition of the new 31-lot subdivision off of Statnvard Drive, it is estimated that approxirmtely 12 vph would be added to the southbound approach traffic based on Institute of Transportation En~kqnee. rs trip generation rates, for a total of 70 vph (=58+1.2). This number is "conservative" since it assumes that all outbound vehicles would use Starward Drive. Therefore, even with the addition of the subdivision, a traffic signal at AVB/gtarward Drive is still not warranted based on peak hour traffic volumes. Conclusions The sight distance analysis shows that the sight distances to the northwest and northeast comer at Starward Drive from westbound AVB are adequate for vehicles traveling at 35 mph and the existing crosswalk markings are appropriate as is. Observations at the intersect/on indicate that the great majority ofpedestr/ans cross AVB at the marked crosswalk on the east leg, where the sight distance is better. To encourage pedestrians to use this crosswalk, a standard "NO PED CROSSL-NIG, USE CROSSWALK" (Type R49) can be installed on the northwest and southwest comers directing pedestrians to the cross AVB at the northeast and southeast corners, respectively. Removing the crosswalk form the east leg in an attempt to encourage pedestrians to cross at the existing signal at AVB/Donohue Drive would probably be ineffective, since pedestrians may have to travel up to 600 feet more to reach the/r destination. The signal warrant analyses reveal that traffic signal installation is not warranted based on the Pedestrian Volume Warrant, Accident Experience Warrant and the Peak Hour Volume Warrant, even with estimated volumes generated by the new 3 l-lot subdivision on Starward Drive. However, once the new subdivision is built and fully occupied, this intersection should be reevaluated to determine whether southbour~d Stam,ard Drive ~:raffic has increased significantly. Given the close proximity of the existing signals at AVB/Donohue Drive and AVB,rRe~onal Street, signalizing AV'B/Stam,ard Drive would negatively impact the flow of traffic on AVB. C."umy domm~ntshmemo'~ignal-xwall~. 157001Tg0 x FIRE STATION