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HomeMy WebLinkAbout7.1 2nd LftTrnLnEbndDB@VPCITY OF DUBLIN AGENDA STATEMENT City Council Meeting Date: December 14, 1987 SUBJECT: Second Left Turn Lane, Eastbound Dublin Blvd. at Village Parkway EXHIBITS ATTACHED: 1) Report from TJKM 2) Diagram of Proposed Change (2 pages) RECOMMENDATION: /~z ~-~~/"~pr°ve 80 feet of striping for westbound right-turn /~'O?'lane onto northbound Village Parkway, and direct Staff to proceed with one of the following options: (a) include the full scope of work within the 1988-89 proposed CIP, or (b) begin the design process at this time and include the construction cost in the 1988-89 proposed CIP, which will require a budget transfer in the amount of $5,000. FINANCIAL STATEMENT: Estimated cost of 80 feet of striping to be done as soon as possible is $200. Estimated cost of improvements is $10,000 to $15,000; estimated cost of design and administration is $3,000 to $5,000. DESCRIPTION: At a recent meeting, the City Council requested that Staff investigate the feasibility of creating a second left turn lane for eastbound Dublin Boulevard at Village Parkway. This second left turn lane is consistent with the ultimate planned improvements for Dublin Boulevard. TJKM, the City's Traffic Engineer, has studied the proposed improvement on the basis of existing conditions and finds as follows: Service Level The intersection level of service would be improved significantly by this proposed modification (from Level D to Level C during the noon hour and from Level D to Level B during the late afternoon peak hour). The overall cycle length would be significantly shortened, which would improve the perceived signal operation for vehicles in other movements, and the lengths of the queues at other approaches would be reduced. Required Modifications New detectors would need to be installed for the eastbound through lane, and the existing detectors in the inner through lane would need to be modified to function as left-turn detectors. The signal would be modified simultaneously with the restriping. Existing signal indications are not adequate; the existing head would have to be modified or replaced. The specific requirements would be determined as part of the signal modification plan. Two eastbound left turn lanes and two through lanes will fit within the existing curb-to-median width. On-street parking is already prohibited on the south side of Dublin Blvd. between Village Parkway and the Zone 7 channel. In order to allow for transitioning, parking should also be prohibited for an additional 420 feet to the west (in other words, under 1-680 and in front of the Dublin Cinema). This parking consists of approximately 10 spaces, only four of which are in front of the theater, and is very rarely utilized. Its elimination should not inconvenience any of the businesses in the area. Notices regarding the proposed improvements have been sent to businesses and property owners at or near the intersection. A resolution establishing the no parking zone must be adopted in order to implement this recommendation and will be placed on a future agenda if and when the improvements are made. Westbound Right Turn Lane TJKM's report discusses the possible conflict involving traffic turning right from westbound Dublin Blvd. onto northbound Village Parkway. At this time, TJKM recommends retaining the existing YIELD sign rather than installing a STOP sign or removing the triangular island. It is recommended, however, that the westbound right turn lane be striped an additional 80 feet further east in order to more ~clearly delineate where a vehicle turning right must make the commitment to turn right. This curb is already designated a no- parking zone. Staff would recommend performing this particular striping as soon as possible in order to alleviate conflicts between vehicles which pass on the right to make the turn onto Village Parkway and those in the through lane which decide to turn right at the last minute. Cost Factor and Recommendation TJKM estimates that construction cost of these improvements would range between $10,000 and $15,000, including signal modification, detector modification, and striping. A more definite figure would be determined during the design process. An additional $3,000 to $5,000 will be needed to prepare design drawings and specifications and for project administration and inspection. Because of the significant Service Level improvement at this intersection, Staff recommends that the City Council authorize the 80 feet of striping for the westbound right turn lane and direct Staff to proceed with one of the following options: (a) to include the total project in the proposed 1988-89 Capital Improvement Program (design as well as construction)~ or (b) to proceed with the design phase of the project at this time and include the construction phase cost in the proposed 1988-89 CIP. If option (b) is selected, a budget transfer in the amount of $5,000 would be necessary. Staff estimates the design process will require approximately two to three months to complete, and it is anticipated that Staff would request approval from the City Council to solicit bids on this project during the current Fiscal Year, with construction to take place in July of 1988 so that construction costs would fall into the 1988-89 Fiscal Year. MEMORANDUM 4637 Chabot Drive, Suite 214 Pleasanton Ca. 94566 (415) 463-0611 DATE: TO: FROM: SUBJECT: November 16, 1987 Lee Thompson Michelle DeRobertis Eastbound double left turns on Dublin Boulevard at Village Parkway At your request, we have investigated the feasibility of striping two eastbound left-turn lanes on Dublin Boulevard at Village Parkway. We compared the request with the Dublin Boulevard Plan line. Since double eastbound left-turn lanes are shown on the Dublin Boulevard Plan Line, this request is consistent with ultimate planned improvements for Dublin Boulevard. We reviewed the implications of providing double left-turn lanes in the short term on the signal operation, the resulting lane widths, the on-street parking, and on other conflicting movements at the intersection. Traffic Signal Operation Vehicle turning templates were used to assess the ability of the intersection to accommodate eastbound double left-turn lanes simultaneously with the westbound left turn movement, i.e. in the same signal phase. It was determined that the eastbound double left-turning vehicles would not conflict with the westbound left- turning vehicles. Therefore, the existing left-turn phasing which allows the eastbound and the westbound left-turn movements to proceed simultaneously could be retained, and split phase operation would not be necessary. Providing double eastbound left-turn lanes would necessitate installing new detectors for the eastbound through movement and relocating the existing detectors in the two through lanes to fit within the new lane lines. The existing detectors in the inner (northernmost) through lane will also have to be rewired to function as left-turn detectors. Such changes would require a signal modification plan and ~vould be required simultaneously with the re-striping of the eastbound lanes to have two through and two left-turn lanes. The signal indications for the eastbound left turn movement would not be adequate for the re-striped lanes. A new left-turn signal indication, either by reprogramming the existing signal head or by replacing the signal head, would be necessary. The specific requirements would be determined as part of the signal modification plan. Two eastbound left turn lanes would improve the existing intersection level of service during both the noon hour and the late afternoon peak hour by at least one service level, (from LOS D to LOS C during the noon hour and from LOS D to LOS B during the late afternoon peak hour). Because the signal is traffic-actuated, with a maximum timing of 55 seconds for the eastbound left-turn phase alone, the overall cycle length would be significantly shortened with two eastbound left turn lanes. This would improve the perceived signal operation for vehicles in other movements, and would also reduce the length of the queues at the at~proaches of the other movements. PLEASANTON-SACRAMENTO.FRESNO.CON£ORD Mr. Lee Thompson -2- November 16, 1987 Lane Re-striping and On-street Parking Two eastbound double left-turn lanes could fit within the existing curb to median width of 46 feet. The two left-turn lanes should be 10 feet wide, the northernmost through lane should be 11 feet wide and the curbside through lane should be 15 feet wide. On-street parking on Dublin Boulevard is currently prohibited (via red curb) on the south side of the intersection from Village Parkway west to the drainage channel. In order to have adequate transitioning, parking should be prohibited via red curb for an additional 420 feet to the west, (i.e. underneath 1-680). At approximately 740 feet west of Village Parkway, the striping should deviate from the existing striping in order to shift the through lanes to the south to fit two left-turn lanes. The recommended transition and lane striping is depicted in Figure 1. Impacts on Westbound Right-Turn movement. The westbound to northbound right turn movement is controlled by a YIELD sign due to the raised island which separates the right-turn movement from the other westbound movements. Although the right-turners are supposed to yield to all other traffic, including the eastbound to northbound left-turners, there is such a high demand for the right-turn movement that the right-turners try to squeeze through during all phases. The major movements that conflict with the westbound right-turners are the eastbound left-turners and the southbound U-turners. The situation is complicated by the fact that many left turners turn into the curbside lane to enter the driveways near the intersection. Many right-turners, however, assume that the curbside lane is available for their turn. Conflicts and near misses occur in front of the shared Wendy's/Kentucky Fried Chicken driveway. The Dublin Boulevard Plan Line indicates that, ultimately, this island will be removed and that right-turners will be brought under signal control. This will require relocating the existing signal pole on the island and other signal modifications. Although the intersection operation would be improved if the right- turners were brought under signal control, removing the island and relocating the signal pole would involve considerable expense. The benefits of both retaining the YIELD sign and replacing it with a STOP sign were considered. If the YIELD sign were retained, the proportion of signal time that is allotted to the eastbound left turners would be significantly reduced, thereby reducing the right-turning vehicles' impatience. Also, having two lanes o£ eastbound left-turners should cause the right-turners to obey the YIELD control more effectively, since they would observe left-turning vehicles turn into the curbside lane. We feel that replacing the YIELD sign with a STOP sign would reduce some confusion and would eliminate potential conflicts between the westbound right-turners and the eastbound left-turners. However, it was felt that the potential for the right-turners to "back-up" and to block the westbound through movement during their green phase was too great. Therefore, it is recommended that the island and the YIELD sign be retained in the interim before the ultimate improvements are implemented. Although we feel the overall intersection operation will improve due to the double eastbound left-turn lanes, this intersection should be monitored, and the recommendation re-evaluated after the double left-turn lanes are implemented. It may be necessary to replace the YIELD sign with a STOP sign or even to remove the island if the number of conflicts increase, and the intersection operation deteriorates. Mr. Lee Thompson -3- November 16, 1987 It is also recommended that the lane for westbound right-turners be striped an additional 80 feet further to the east, to approximately as far east as the existing westbound left-turn lane. This would reduce the conflicts between westbound vehicles by more clearly delineating where a vehicle desiring to turn right must make the commitment to turn right. This striping change is shown in Sheets 1 and 2. Since the curb along this section of Dublin Boulevard is already painted red, no additional parking restrictions would be necessary. Conclusion Two eastbound left turn lanes can be accommodated with the existing signal phasing and in the existing curb-to-median width at the eastbound approach of Dublin Boulevard at Village Parkway. However, a signal modification plan would be necessary in order to design the required changes to the detectors and to determine the correct signal indication modifications for the eastbound left-turn movement. The signal modification plan would cost approximately $3,000 to $4,000. The cost of the relocating existing detectors, installing new detectors, related rewiring and controller changes would cost approximately $5,000. Depending on the extent of the necessary changes, the new signal indication would cost between $1,000 and $5,000. The cost of re-striping the eastbound lanes would be approximately $I,000. Therefore, the total cost of implementing double left-turn lanes would range from $10,000 to $15,000. The overall intersection operation would improve by providing double left-turn lanes. The cycle length would be reduced, resulting in less delay and shorter queues at the other movements. The level of service would improve from LOS D to LOS C, and LOS B, during the midday and late afternoon peak hours, respectively. The Dublin Boulevard Plan Line depicts that, ultimately, the westbound right turn movement will be brought under signal control by removing the raised island. Although this would benefit the existing situation as well as the conditions after double left-turn lanes are implemented, it is not required. Having two lanes of eastbound left-turners should cause the westbound right-turners to be more aware of the potential for conflicts and to obey the YIELD sign more effectively. Therefore, it is recommended that the existing YIELD sign be retained and the intersection be monitored. If the conflicts continue or worsen, further improvements should be implemented. In addition, it is recommended that the westbound right-turn lane be striped for an additional 80 feet to the east. This would make westbound drivers more conscious of the potential for conflicts between vehicles which have committed themselves to turning right and other westbound vehicles in the curbside lane. nlc Attachments 157-001 ' '~ ~ ' ....... '~ ' *~: ' . '~ ~ *"~ "'~ ~: ~.'' -- ~ . .... :~ ~'' r '' '~' ~'' : :' ''~' '--'~ ': :' '".:'.:'~. .'.. ' -- :. ' ~ .,, ~,' ~' ~'~'~' ' , :--. '''; '; --~'' '~--.,.. ,:,` .:. ~'''''' ' '..~__::, ~ .... 4' ~''''. ..... --~'~ ~,~,~'~'' ' '' ~ ~ .. ~ '.., ...... .~ ' ' ' ' ' '.' ' ' ' ' ''~''~ ''~.~ '' · "~ ...... ' ~ ''' ~Z' .1~'~'~ .... --;~ -- ' .... .~: .., ~"~ ' ' ' ' '~" ' ' ' ': ' ~ ' .... ~,. - i . ~ .... ~ .............. ~ ........... .'-- ' :~. , , "~..~-~ -'-4'-'~--'':. .~:, ...: ~' -"':._.,-~:""'.~' ?"-~ ~ '%~'. . ~. ~. . ..,~'"' ...... - ~ ~ . 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