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HomeMy WebLinkAboutItem 6.1 StopSgnsDB@SilvergateCITY OF DUBLIN AGENDA STATEMENT City Council Meeting Date: April 27, 1992 SUBJECT: Public Hearing: Installation of Stop Signs Boulevard at Silvergate Drive Dublin EXHIBITS ATTACHED: 1) 2) 3) 4) Resolution Report from TJKM Location Map Copy of public hearing notice and mailing list RECOMMENDATION: 1) , 5) Open public hearing Receive Staff presentation and public comment Question Staff and the public Close public hearing and deliberate Adopt resolution approving installation of 3-way stop signs on Dublin Boulevard at Silvergate Drive. FINANCIAL STATEMENT: Installation cost is included in the Dublin Boulevard/Silvergate Drive intersection Capital Improvement Project (#9601), which is ultimately being funded by developer contribution. DESCRIPTION: In a separate item on the agenda, Staff is recommending award of bid for Phase I of the Dublin Boulevard/Silvergate Drive intersection project. The project will reconfigure this intersection to a conventional "T" design. These improvements are intended to improve driver and pedestrian safety. Currently, this intersection is controlled by stop signs for southbound traffic on Silvergate Drive and eastbound traffic on Dublin Boulevard. Westbound traffic on Dublin Boulevard is not required to stop. The options for control at this intersection are as follows: One-Way Stop (southbound Silvergate only) Two Way Stop (southbound Silvergate and eastbound Dublin Blvd., similar to existing configuration.) Three-Way Stop (all three approaches) Traffic Volume As indicated in TJKM's report, total traffic volume entering the intersection for the highest eight hours was 3,679 vehicles, or an average of 460 vehicles per hour. This volume satisfies the first part of the warrant which requires an average of 300 vehicles per hour. Traffic entering from the minor street (Silvergate Drive) however, averaged only 112 vehicles, which is less than the required 1/3 of total volume. Therefore, the volume warrant is not fully satisfied. It should be noted that the 24-hour traffic count was conducted on a Tuesday and therefore does not include the Sunday traffic volume for Valley Christian Center; however, it is assumed that most of that traffic would be using Dublin Boulevard rather than Silvergate Drive. ITEM NO ~ COPIES TO TJKM ~ Accident History Review of the City's accident maps and files indicates that no accidents have occured at this intersection within the past two years. The accident warrant requires five or more accidents of a type correctable by stop signs within a 12- month period. Therefore, the accident warrant is not satisfied. Visibility The visibility warrant requires 160 feet clear visibility in all directions. When measured from the proposed new limit line on Silvergate Drive, visibility in both directions on Dublin Boulevard slightly exceeded 160 feet. Therefore, the visibility warrant is not met. However, this warrant is theoretically based on residential neighborho6ds with speeds of 25 to 30 mph. The posted speed limit on the eastbound Dublin Boulevard approach is 40 mph. The safe stopping distance on wet pavement at 40 mph is calculated at 325 feet. Therefore, although the standard warrant for visibility has not been satisfied, other sight distance conditions may still warrant a stop sign. Other Issues While the minor street (Silvergate Drive) traffic volume does not meet the warrant for all-way stop sign control, southbound drivers on Silvergate Drive are accustomed to having eastbound drivers on Dublin Boulevard come to a stop. Staff feels that removal of the eastbound control (in other words, a one-way stop on Silvergate only) could result in accidents if the Silvergate motorists continued to expect eastbound drivers to stop. The addition of the westbound stop sign would assist in assigning right-of-way at this intersection. Recommendation Staff recommends that the City Council conduct a public hearing, deliberate, and adopt the resolution approving installation of stop signs on Dublin Boulevard at Silvergate Drive, to become effective with construction of the Capital Improvement Project. a:(corres)\apr\afstdsss Page 2 RESOLUTION NO. -92 A RESOLUTION OF THE CITY COUNCIL OF THE CITY OF DUBLIN APPROVING INSTALLATION OF STOP SIGNS ON DUBLIN BOULEVARD AT SILVERGATE DRIVE The City Council of the City of Dublin hereby resolves as follows: Section 1: Pursuant to City of Dublin Municipal Code Section 6.04.060, and in the interest of public safety, a stop sign shall be erected on westbound Dublin Boulevard at ~he intersection of Silverga~e Drive. (The effect of this approval will create a three-way stop at the Dublin Boulevard/Silvergate Drive intersection.) Section 2' Said stop sign shall be added to Section 6.16.010 of the City of Dublin Traffic Code. PASSED, APPROVED, AND ADOPTED this 27th day of April, 1992. AYES: NOES: ABSENT: Mayor ATTEST: Gity Clerk a: ~corres) \apr\resodsss DATE: TO: FROM: SUBJECT: April 10, 1992 Mehran Sepehri Carl D. Springer, Christopher S. Kinzel Dublin Boulevard]Silvergate Drive STOP Sign Warrant Analysis This is to present the results of TJIGWs analysis related to STOP sign control at the intersection of Dublin Boulevard/Silvergate Drive in the City of Dublin. The three-legged intersection is unconventionally configured, with STOP sign control on the eastbound approach of Dublin Boulevard and on the Sflvergate Drive approach. A northward-bending concrete median on Dublin Boulevard causes the movement from westbound Dublin Boulevard to northbound Silvergate to act as a through movement; westbound vehicles on Dublin Boulevard must turn left to continue west on Dublin Boulevard. The City is planning to rebuild the intersection with a configuration more like a conventional "T"-intersection, with east-west through traffic on Dublin Boulevard ch~nnelized as through movements instead of turn movements. In the future, the intersection is planned to be widened and signalized as part of improvements related to development in West Dublin. The purpose of this study was to evaluate what kind of control is needed in the interim. Three intersection control schemes are possible: · One-way STOP control: a STOP sign on the Silverga~e Drive approach only. · Two-way STOP control: STOP signs on Silvergate Drive approach and the Dublin Boulevard eastbound approach, similar to the existing configuration. Three-way STOP control: STOP signs on all three approaches to the intersection. TJKM conducted 24-hour machine volume counts at the intersection between Friday, March 12, and Tuesday, March 18, 1992. The need for three-way STOP sign control on Dublin Boulevard under the proposed configuration was evaluated based on the stop sign warrants presented in Attachment A. The following discussion looks at each of the warrants in turn. Warrant 1: Volumes (300 vehicles per hour entering intersection for an 8-hour period) The 24-hour machine counts revealed that the highest 8-hour vehicular volume entering the intersection was 3,679 vehicles, an average of 460 vehicles per hour. Therefore, the first half of Warrant I is satisfied. However, the volume approaching the intersection from Silvergate Drive during the snme 8 hours was only 892 vehicles, or 112 vehicles per hour. This is less Mehran Sepehri -2- April 10, 1992 than the required one-third of the total volume entering the intersection during the highest 8 hours. (Refer to Table I for more details on current volumes.) Therefore, the current volume does not fully satisfy this warrant. Table I Highest Hourly Voh~rnes at Intersection of Dublin Boulevard/Silvergate Drive Hour Dublin Boulevard Silvergate Drive Total Starting At WB EB SB Volume 7:00 a.m. 121 130 224 475 8:00 227 290 143 660 9:00 113 90 88 291 3:00 p.m. 208 239 98 545 4:00 202 115 78 395 5:00 265 177 99 541 6:00 229 110 95 434 7:00 179 92 67 338 Total 1,544 1,243 892 3,679 Average 193 155 112 460 Note: Traffic count taken March 17, 1992 Warrant 2: Accidents (5 correctable accidents in a 12-month period) Discussion with City staff and perusal of the City spot accident map indicate that no accidents have occurred at the intersection within the past two years. This warrant requires five or more accidents of types capable of correction by STOP signs within a 12-month period. Therefore, the accident warrant is not met. Warrant 3: Visibility (Greater than 160 feet in each direction) The sight distances on both Dublin Boulevard approaches to the intersection were measured from the planned Silvergate limit line. Visibility in both directions would slightly exceed 160 feet. Therefore, this warrant is not met. However, this warrant is most likely based on low, residential speeds between 25 and 30 mph. The posted speed on the eastbound Dublin Boulevard approach is 40 mph. The Institute of Traffic Engineers' Transportation and Traffic Engineering Handbook (2nd Edition, 1982) states that 325 feet is a safe stopping sight distance for a travel speed of 40 mph on wet pavement. The sight distances for both Dublin Mehran Sepehri -3- April 10, 1992 Boulevard approaches under the planned configuration would be less than 325 feet. Therefore, although the City's warrant is met at this intersection, sight distance considerations may still warrant a STOP sign. Other Issues Because a STOP sign on the westbound approach would be new and therefore ~,,~familiar, TJKM recommends that a W17 (pictorial "STOP AHEAD) sign be installed 350 feet in advance of the intersection on this approach. Summary and Conclusions The City's warrants for STOP sign installations were reviewed based on the current vehicular activity and historical safety information. It was found that: · The current hourly traffic volumes do not meet the total required. · There were no reported accidents at this location within the last two years. · Vehicle sight distances will satisfy the City's visibility warrant, but will not be satisfactory under the proposed configuration. In conclusion, it is recommended that: 1. Although the City's established STOP sign warrants are not met, it is recommended that all-way STOP sign control be installed at the intersection until the intersection is widened and signalized. 2. In addition, TJKM recommends that a W17 (pictorial "STOP AHEAD") sign be installed 350 feet in advance of the intersection on the westbound Dublin Boulevard approach. nk 157-O01m.lk2 fl601~ II452I ---- N-s\S ITY OF DUBLIN "Celebrating 10 Years Of Cityhood 1982-1992" RO. Box 234.0, Dublin, Californ:,a 94568 City Offices, 100 Civic Plaza, Dublin, California 94568 PUBLIC HEARING NOTICE The City of Dublin is preparing to award a construction contract which will change the Dublin Boulevard/Silvergate Drive intersection to a more normal "T" configuration. This intersection is currently controlled by stop signs for the southbound and eastbound directions, with no restriction on westbound traffic. City Staff has performed a traffic study relative to the "warrants" or criteria for recommending a three-way stop intersection. These criteria include traffic volumes, visibility, and accident history. While the warrants for three-way stop control have not strictly been met at this intersection, City Staff is recommending that a stop sign be added for westbound traffic in order to improve safety. A public hearing regarding this matter has been scheduled for the regular City Council meeting of April 27, 1992, which will be held at 7:30 p.m. in the Council Chambers, Dublin Civic Center, 100 Civic Plaza, Dublin, California. The City of Dublin encourages interested parties to attend public meetings and comment on the issues being discussed. If you wish to provide testimony and are unable to attend the meeting, written comments which are delivered to the City Clerk's office prior to the time of the hearing will be made a part of the public ~ecord. If anyone wishes to challenge ghis matter in court, rhey may be limited to raising only those issues they or anyone else raised ag the public hearing described in this notice or in ~ritgen correspondence delivered to the City Olerk at or before the public hearing. Questions regarding this issue should be directed to the City of Dublin Public Works Department at 833-6630. 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