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Home My WebLink AboutItem 7.2 Eastbound Ramp Metering Stdy~~~~~ ~~~~~ \~/~ CITY CLERK File # 0~^^-J^^~ AGENDA STATEMENT CITY COUNCIL MEETING DATE: October 21, 2008 SUBJECT: Presentation of the Eastbound Ramp Metering Before-and-After Study Results Report Prepared by: Jaimee Bourgeois, Sr. Civil Engineer (Traffic) ATTACHMENT: Map of Study Area covering Dublin RECOMMENDATION: Receive the presentation and provide comments as appropriate. FINANCIAL STATEMENT: There is no cost associated with this item. DESCRIPTION: Dublin City Council Resolution No. 168-01 declared City support for the I-580 Smart Corridor Management Plan, including the phased implementation of ramp metering on I-580 between I-880 and the Altamont Pass. The ramp meters on eastbound I-580 were activated in June 2003 at the following three interchanges: • Dougherty Road / Hopyard Road • Hacienda Drive • Tassajara Road /Santa Rita Road A "before and after" study of Phase 1 implementation was completed, which demonstrated an increase in freeway travel speeds and volumes in the vicinity of these three interchanges. With favorable results from Phase 1, Caltrans proceeded with Phase 2 in January 2008, the activation of ramp metering at the remaining eastbound on-ramps, namely: • San Ramon Road /Foothill Road • Fallon Road / El Charro Road • Airway Boulevard (SR 84) • N. Livermore Avenue • First. Street • Vasco Road • Greenville Road COPY TO: Page 1 of 3 ITEM NO. G:\TRANSPORTATION\Regional\I-580 Ramp Metering\agst_EB_RampMetering_Results.doc Because the peak in the eastbound direction occurs during the PM commute period, the eastbound ramp metering is only active in the evening, starting at 2:30 PM and ending at 7:30 PM. The primary goal of ramp metering is to improve the efficiency of traffic flow on the freeway by breaking up (i.e., metering) platoons of vehicles entering the freeway, which create bottlenecks. Improving the efficiency maximizes capacity and facilitates increased travel speeds. The secondary benefit of this improved efficiency is that motorists are more likely to travel on the freeway instead of bypassing the congestion via local parallel routes, such as Dublin Boulevard. The strategy for the implementation is to select fast metering rates at those ramps where it is desirable to encourage use and slow metering rates at those ramps where it is desirable to discourage use. For example, within Dublin a fast metering rate was applied at the San Ramon Road /Foothill Road interchange to encourage motorists to access the freeway at this upstream point of the Tri-Valley I-580 corridor. On the other hand, because there has been a significant amount of cut-through traffic through the City of Dublin to Fallon Road, a slow metering rate was applied at the Fallon Road / El Charro Road interchange. Caltrans worked cooperatively with staff from the Cities of Dublin, Pleasanton .and Livermore to develop the metering strategy and metering rates. As expected, significant traffic back-ups occurred at many of the on-ramps during the first week of activation, primarily on Fallon Road. As motorists reacted to the change and modified their travel routes, the queues at each ramp decreased and became more balanced throughout the corridor. Before the implementation of Phase 2, a "Before" study was conducted. Traffic volumes and travel times were collected on the freeway and local arterials, as well as queue lengths on the freeway on-ramps. The eastern portion of the study area covering Dublin is illustrated on the Study Area Map (attached). Once optimal efficiency was achieved, an "After" study was conducted. The results were then summarized into a "Before-and-After" study report. This study was funded by a Traffic Engineering Technical Assistance Program (TETAP) grant from the Metropolitan Transportation Commission. Similar to Phase 1, the "Before-and-After" study for Phase 2 demonstrated favorable results, which are generally summarized as follows: ^ Eastbound travel time on the freeway between San Ramon Road and Tassajara Road decreased by 33% (18 minutes to 12 minutes) ^ Eastbound travel time on the freeway between Tassajara Road and Greenville Road decreased by 30% (13 minutes to 9 minutes) ^ Combining these two segments, total travel time on the freeway decreased by 32% (32 minutes to 22 minutes) - a 10 minute savings The combination of travel time savings on the freeway and added delay at the Fallon Road on-ramp created by the meter resulted in fewer cars using Dublin Boulevard to by-pass freeway congestion. This is substantiated by the following results: ^ Traffic using the Fallon Road / El Charro Road on-ramp decreased by 44% (from 3,090 to 1,735 vehicles) ^ Volumes on Dublin Boulevard east of Myrtle Drive decreased by 12% (from 5,005 to 4,420) ^ Volumes on southbound Fallon Road decreased by 49% (from 2,660 to 1,350) Page 2 of 3 A summary of the before and after ramp volumes is provided in Table 1. TABLE 1 D bl 4-Hour Ram Volume Com arison u in On-Ramp at: Before After ° Chan a /o San Ramon Road 4,235 3,640 - 595 (-14%) Dougherty Road 1,230 1,310 +80 (+7%) Hacienda Drive 1,880 1,020 - 860 (-46%) Tassajara Road 1,465 .1,280 -185 (-13% Fallon Road 3,090 1,735 -1,355 (-44%) One consequence of ramp metering is that motorists are delayed at the on-ramp prior to entering the freeway. The goal is that system-wide time savings will exceed system-wide delay. The maximum wait time observed at each of the on-ramps from Dublin is presented in Table 2. At most ramps, the delay is 4 minutes or less. This delay is more than offset by the time savings that would be achieved on the freeway. The only exception is at the Tassajara Road on-ramp under worst conditions. A maximum wait time of about 11 minutes was observed at some point between 5:00 and 6:00 PM. This delay is not offset by the freeway time savings. While the delay at the Tassajara Road on-ramp is usually less than the worst-case observed 11 minutes, it is consistently the most congested on-ramp within Dublin. Motorists are encouraged to use Hacienda Drive as an alternative to Tassajara Road. Because of the slow metering rate at Fallon Road, shifting to Fallon Road is not recommended. TABLE 2 -Dublin On-Ramp at: Maximum Queue No. of Vehicles Approximate Maximum Wait Time San Ramon Road 18 2 min : 42 sec Doughert Road 5 < 1 minute Hacienda Drive 19 3 min : 58 sec Tassajara Road 57 10 min : 56 sec Fallon Road 14 2 min : 20 sec Over the course of one year,. the ramp metering will result in an estimated savings of 1,096,650 vehicle- hours of delay, which equates to $13,817,840 of economic savings. Phase 3 of the Tri-Valley ramp metering, which entails activation of the westbound ramps during the AM commute period, was recently implemented. Caltrans continues to monitor traffic and modify the metering rates at each ramp in an effort to achieve optimal efficiency. Once stability is achieved, an "After" study will be conducted and summarized into a "Before-and-After" study report. The results of that report will be presented to the City Council at a future meeting. RECOMMENDATION: Staff recommends that the City Council receive the presentation and provide comments as appropriate. Page 3 of 3 ~_~ ~,,_~, ~ ~'d'~0C1~, ~`~. Section I: Introduction Figure 1: Study Area d~~ ~ _...~.. ~ g, ~ `S~* ~s'~ ~Rougnerry ~ ~t ~, q.. Hi11s Park Tassajara Cr~ek ~ ti ~ ~ ._.y ~ F.cgionel Pa~k ^p~ ~ ~ fY~~ c~.. ~ ~ ~ ~ ~ ~ ~ ~~ N ~Way~ Q ~ ~ ~ ~ ~ g ~ ~ ~ ~^~ ~ ~ ,~ = 42in st ~ ~:~` dA ~' "~'~n ~ '~. a Continued on ne~ct q~~.~a~ ~ 4 ~ . Jth ~t~ C&mp F~erk~ h4liie+rY. . ~ . . , ..` e t . . . '~ ~ ~ $th 8t Re~~srv~rtam~ ~ ~ -," as~ 3 Broder 8hd ~ ~, .-. ~~ ~ ~ , .:~ Shannon~ `~i 78rttsraCk . O~ ...~Kanandrnski ~ .~ ~?~ ~... 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