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HomeMy WebLinkAbout8.2 DavonaSierraEtcSpdStdy CITY OF DUBLIN AGENDA STATEMENT MEETING DATE: August 8, 1983 SUBJECT Speed Studies - Davona Drive, Sierra Court, Sierra Lane, Starward Drive, and Trinity Court EXHIBITS ATTACHED RECOMMENDATION 2) Traffic Engineer's report dated August 2, 1983 Ordinance Waive reading and introduce ordinance establishing speed limits on Sierra Court and on Sierra Lane. Authorize installation of additional 25 mph. sign for N/B traffic on Starward at Gunshot, and 25 mph signs on Sierra Court, north of Trinity Court and on Trinity Court. FINANCIAL STATEMENT: Cost for installation of speed limits signs approximately $100.00 each ($700.00) total. Sufficient funds have been budgeted. DESCRIPTION: The Traffic Engineer has undertaken several speed studies as the result of requests from residents and the Police Dept. to investigate speeding problems in various areas around town. As indicated in the Traffic Engineer's memorandums(see attached), stop signs, reduced speed limits, and traffic humps are not recommended to control speed at those locations studied. The Traffic Engineer has recommended establishing speed limits in the industrial area on Sierra Lane and on Sierra Court from Dublin Boulevard to Trinity Court at 30 mph. These streets are zoned and not posted and, therefore, a prima facie speed limit of 25 mph currently applies. The Traffic Engineer has also recommended posting 25 mph signs on Sierra Court north of Trinity Court and on Trinity Court. These streets are also unzoned and not posted. The current prima facie speed limit is 25 mph. Lastly, it is recommended that an additional 25 mph sign be installed for northbound traffic on Starward at Gunshot. It is Staff's position that these modifications will reduce confusion for motorist-s in those areas studied and provide a more realistic speed limit where warranted. With respect to the speeding in the vicinity of Davona Drive, it is Staff's position that radar enforcement would be the only effective tool in reducing speeding on that street. If the City is successf~l in its application to the State Office of Traffic Safety for a city wide traffic study, Staff will be able to address the utilization of a radar in a more comprehensive manner. ITEM #~ ~ ~,~ · COPIES TO: MEMORANDUM DATE: August 2, 1983 TO: City Engineer FROM: Chris Kinzel SUBJECT: Result of Speed Studies I have completed an investigation of requests made by Dublin residents concerning speeding problem on various streets. As a part of our investigations, we obtained radar speed checks on each of the streets from unmarked vehicles for the purpose of determining prevailing motorist practices. We also made repeated field surveys of the area in order to observe problems and possible solutions first hand. Two general conclusions stem from these surveys. First, there is a need for Dublin to continue the practice of establishing 'realistic' speed limits. 'Unrealistic speed limits are those which are lower than practical with the attempt to significantly and permanently lower" vehicle speeds. Studies performed throughout the state and the nation prove that motorists ignore unreasonably low speed limits regardless of the degree of enforcement. While it is hard to believe, on a given stretch of roadway, average speeds of motorists will not change regardless what speed limit sign is displayed or even if there is a sign at all. Most motorists choose their speeds based on observed conditions at the time on the street in question. Speed limits have as their primary purpose the guiding of unfamiliar motorists and the setting of enforcement limits. The second general conclusion from the survey is that the use of radar for speed enforcement would allow the Police Department to enforce speeds more effectively. The use, or threat, of radar by police could affect the speed of motorists who might otherwise select unreasonable speeds. The City still hopes to receive a a grant from the Office of Traffic Safety to fund portable radar sets for use in police vehicles. Residents along streets with prevailing speeds greater than 25 mph tend to request STOP signs, humps, dips and related devices in an attempt to curtail speeding. The general experience is that these devices are ineffective in reducing speeds along the street. On occasions, where the street is used by "through" traffic, the device can become sufficiently annoying to direct traffic to other routes. City Engineer -2- August 2, 1983 A few cities in California have installed humps on streets with on-going speeding problems. Because they constitute an added 'hazard', they have a potential liability to the public agency. They are, however, effective in reducing speeds near the installation. Our survey included t~e following streets: Drive, Sierra Court and Sierra Lane. Davona Drive, Starward Davona Drive: In 1982, the City Council authorized STOP signs at two intersection's along Davona Drive. Since their installation, t~ere continue to be complaints of speeding. Over the years, traffic engineers have noted that the use of STOP signs for speed control is ineffective. Motorists tend to roll through unwarranted STOP signs and then make up for lost time by going even faster. In the case of Davona Drive, we have not made STOP sign compliance checks but in our most recent radar checks we have noted that speeds have not reduced since the placement of the STOP signs. We made a total of 12 radar checks at different times and locations along Davona Drive and found that the average speed is still about 30 mph, and the speed driven at or below by 85 percent of the motorists is still about 35 mph. With t~ese findings, we cannot recommenO any additional STOP signs nor do we recommend a change in speed limits. It is felt that traffic conditions on this street would be susceptible to improvement by radar' enforcement. Starward Drive: This is a collector street more local in nature than Davona. Traffic speeds on this street also average about 30 mph. Starward has relatively sharp curves at both ends and there have been speed-related accidents in the past along the street. It was observed that the existing 25 mph sign for northbound traffic is located near Amador Valley Boulevard near businesses rather than near Gunshot Lane, which is the start of the single family residential district. We are recommending an additional sign near Gunshot Lane. Again, the specific problem on this street lends itself more to an enforcement solution than by any change in signing or regulations. Sierra Court: This street is unzoned at the present time and is the location of numerous business and manufacturing establishments. A speed limit is appropriate and, based on our surveys and driving of the area, a 30 mph limit is recommended between Dublin Boulevard and Trinity Court. From Trinity Court to the north end of the street, a 25 mph limit is recommended. In this northern section, the roadway has curves and the safe speed is lower. Sierra Lane: This is also an unzoned street in the business and manufacturing district. The recommended limit for Sierra Lane between Sierra Court and Doug~erty Road is 30 mph. TABLE I COLLATION OF RAW RADAR SURVEY DATA LOCATION OF SAMPLE* (DIRECTION) Davona Dr e/o Briarwood Ln (EAST) Davona Dr e/o Briarwood Ln (WEST) Davona Dr s/o Bluebell Wy (NORTH) Davona Dr s/o Bluebell Wy (NORTH) Davona Dr s/o Bluebell Wy (NORTH) Davona Dr s/o Bluebell Wy (SOUTH) Davona Dr s/o Bluebell Wy ( SOUTH ) Davona Dr s/o Bluebell Wy (SOUTH) Davona Dr w/o Chatam St (EAST) Davona Dr w/o Chatam St (WEST) Davona Dr w/o Village Pkwy (EAST) Davona Dr w/o Village Pkwy (WEST) Sierra Ct n/o Sierra Ln (NORTH) Sierra Ct n/o Sierra Ln (SOUTH) Sierra Ct n/o Trinity Ct (NORTH) AVERAGE CRITICAL 10 MPH EXISTING RECOMMENDED (50TH) (85TH) PACE SPEED SPEED SPEED SPEED SPEED LIMIT LIMIT 29 33 24-33 25 30 35 26-35 25 32 36 29-38 29 34 27-36 31 34 26-35 33 36 27-36 30 34 26-35 30 36 25-34 30 35 26-35 31 34 27-36 30 36 26-35 25 25 25 25 25 25 25 25 25 31 36 28-37 25 33 39 28-37 25 34 38 29-38 27 34 21-30 * Not necessarily indicative of entire street 25 25 25 25 25 25 25 25 25 25 25 25 25 25 3O 3O 25 TAB LEI COLLATION OF RAW RADAR SURVEY DATA (CONT.) LOCATION OF SAMPLE* (DIRECTION) AVERAGE (50TH) SPEED CRITICAL (85TH) SPEED Sierra Ct n/o Trinity Ct (SOUTH) 28 34 Sierra Ln e/o Sierra Ct (EAST) 30 35 Sierra Ln e/o Sierra Ct (WEST) 29 35 Sierra Ln w/o Dougherty Rd (EAST) 29 34 Sierra Ln w/o Dougherty Rd (WEST) 30 35 Starward Dr n/o Gunshot Ln (NORTH) 29 35 Starward Dr n/o Gunshot Ln (SOUTH) 31 34 Starward Dr s/o Hillrose Dr (NORTH) 3O 34 Starward Dr s/o Hillrose Dr (SOUTH) 29 32 10 MPH PACE SPEED 22-31 26-35 25-34 24-33 25-34 26-35 27-36 25-34 24-33 EXISTING SPEED LIMIT 25 25 25 25 25 25 25 25 25 RECOMMENDED SPEED LIMIT 25 3O 3O 3O 3O 25 25 25 25 AN ORDINANCE OF THE CITY OF DUBLIN ESTA/RLISHING TRAFFIC REGULATIONS The City Council of the City of Dublin does ordain as follows: Section 1. SPEW~ LI~iITS Article 18, relating to "Speed Limits", of the Alameda County Ordinance Code previously adopted by the City of Dublin is amended by the addition of Section 6-628.31 and 6-628.32 to read: %hirty (30) miles per hour (MPH). 6-628.31 Sierra Lane 6-628.32 Sierra Court frc~ Dublin Blvd. to Trinity Court Section 2. POSTING OF ORDINANCE The City Clerk of the City of Dublin shall cause this ordinance to be posted in at least three (3) public places in the City of Dublin in accordance with Section 36933 of the Government Code of the State of California. this day of PASSED AND ADOPTED by the City Council of the City of Dublin on , 1983, by the following votes: MAYOR Attest: