Loading...
HomeMy WebLinkAboutRPT 5 SPEED BUMPS 10-03-88REPORTS NO. 5 10-3-88 DATE: SEPTEMBER 21, 1988 Inter- Corn TO: WILLIAM HUSTON, CITY MANAGER FROM: PUBLIC WORKS DEPARTMENT/ENGINEERING DIVISION · · SUBJECT: INFORMATIONAL REPORT - USE OF SPEED BUMPS/HUMPS AS TRAFFIC CONTROL DEVICES RECOMMENDATION: Receive and file. BACKGROUND: The City Council recently requested staff to prepare an informational report on the use of "Speed Bumps/Humps" as a 'potential traffic control device for controlling vehicular speed on public streets. Staff has researched information through the Police Department, the City Attorney's office and the City's Consultant Traffic Engineer and has summarized this information as shown below. DISCUSSION: The following discussion will dwell primarily on the speed hump in lieu of the speed bump. First of all, it is necessary to define or describe the difference between the two designations. The speed bump is defined as a sudden or sharp three to four inch rise in the Pavement surface and having a base length (longitudinal to the direction of traffic flow) between one and two feet. The speed hump has a gently rounded three to four inch high rise in the pavement and has a minimum base length (longitudinal to the direction of traffic flow) of twelve feet. The most comprehensive document available concerning speed humps is a 1983 'report by a subcommittee of the STATE TRAFFIC CONTROL DEVICE COMMITTEE dated November, 1983. This subcommittee was charged with the responsibility of evaluating speed humps that were already installed in various locations in California. It was also charged with the task of evaluating the liability associated with the use of speed humps. The final conclusion of the subcommittee was that the speed hump did indeed have a place on public streets. Additionally, it should be so designed so.that the actual critical speed at the hump is no less than · 80 percent of the posted speed limit. For example, given the 25 mph limit on a residential street, the speed at the hump should be about 20 nph and between the humps the traffic should be controlled at no more than 120 percent of the posted speed limit, or about 30 mph. The speed hump should be so designed to prevent any loss of vehicular control even for vehicles exceeding the speed limit by 50 percent. INFORMATIONAL REP. ORT - USE OF SPEED BUMPS/HUMPS AS TRAFFIC CONTROL DEVICES September' 21, 1988 Page 2 Another report which has been widely published in Southern California is entitled SPEED HUMPS AND THE THOUSAND QAKS EXPERIENCE.. This report did not reach a conclusion as to whether the speed hump should or should not be used, but only to make available the results of the author's research and testing of the speed hump. The primary reason for this study was the continuing disregard for speed limits in residential areas. These Thousand Oaks tests refined the original configuration of the speed bump into a new form called the speed hump which maintained traffic speeds at a tolerable level while minimizing unnecessary through traffic. This provided a device to control speed and through traffic without the need for heavy enforcement and restriction of free use of public roads to all citizens and emergency services. More recently, the City's .'consultant traffic engineering firm, BSI Consultants has utilized speed humps in two of its client cities Yorba Linda and Agoura Hills and have found them to be an appropriate use on residential streets. Other southern California cities utilizing the speed hump are Santa Monica, Pasadena and Placentia. The Tustin Police Department has researched data regarding the use of speed bumps/humps and have found the following: .. 1. Overall speed on streets is increased due to the fact that speed decreases while going over the bump/hump but results in increased acceleration between installations. 2. Diversion of traffic to other streets in order to bypass the bump/hump installations. 3. Speed bumps/humps are only effective in areas where ambient speeds are low (15 mph or below) to begin with and the purpose of the installation is to eliminate the excess speed of the relative few. The Police Department suggested the use of a "Rumble Strip" as a potential speed control device. These rumble strips accompanied with appropriate signing would serve as a reminder to the motorist on the posted speed limits. This type of installation may create additional or unusual noise within a residential neighborhood and could result as an irritant to the residents. INFORMATIONAL REPORT - USE OF SPEED BUMPS/HUMPS AS TRAFFIC CONTROL DEVICES September 21, 1988 Page 3 The City Attorney's memo dated 8/30/88 (copy attached) outlines the legal ramifications of the installation of speed bumps/humps within a public street. It reiterates that speed bumps and speed humps are not traffic control devices which have been approved by the State of California, Department of Transportation (Caltrans) and they recommend against installing these devices unless and until such time as they have been approved by Caltrans for use as traffic control devices. Engineering Staff concurs with this recommendation. 9ob Ledendecker Director of Public Works/City"Engineer BL:bf Attachment OAT[: August 30, 1988 Inter-Corn $ UB,J EI:T :' DENNIS BARNES, CITY TRAFFIC ENGINEER CITY ATTORNEY SPEED BUMPS/SPEED 'HUMPS' The question has 'come up again as to whether the City could install speed bumps and/or speed humps. Section 21401 of the Vehicle Code of the State of California provides as follows: Except as provided in Section 21374, only those official traffic control devices that conform to the Uniform Standards and Specifications promulgated by the Department of Transportation shall be placed upon a street or highway. (Section 21374 relates only to "Directional markings for tourists" and authorizes' painting the surface of street-s with lines, arrows or other symbols for the purpose of 'directing visitors and tourists and so has no relevance to speed bumps or .humps.) Speed bumps and speed humps are not traffic control devices which have been approved by the Department of Transportation. Vehicle Code Section 21400 provides as follows: The Department of Transportation shall, after consultation with local agencies and public hearings, adopt rules and regulations presc'ribing uniform standards and specifications for all official traffic control devices placed pursuant to this code, including, but not limited to, stop signs, yield right-of-way signs, speed restriction signs, railroad warning approach signs, street name signs, lines and markings on the roadway and stop crossing signs pursuant to Section 21364. The Department of Transportation shall, after notice and public hearing, determine add publicize the specifications for uniform types of warning signs, lights and devices to be placed upon a highway by any person engaged in performing work which interfers with or endangers the safe movement of traffic upon that highway. l~rcvideo for in t?.:s Section ='~all upon a highway to warn traffic of wcrk is being performed on the highway. Any control devices or markings installed upon traffic barriers on or after January 1, 1984, shall conform to the Uniform Standards and Specifications required by this Section. In the case entitled Rumford v. City of Berkeley (31 Cal. 3d 545) the Supreme Court of California granted a writ of mandate directing a City to remove barriers it had placed on certain of its streets for the purpose of controlling traffic. The barriers partially closed the streets but left them accessible to use for local traffic. The court held that the streets of a City belong to the people of the State, and every citizen of the State has a right to the use thereof, subject to the control of the State Legislature. The right of control over street traffic is an exercise of the part of the sovereign power of the State. The court pointed out that the State's plenary power in its preemption of the entire field of traffic control are set forth in Vehicle Code Section 21 which provides: Except as otherwise expressly provided, the provisions of this Code are applicable and uniform throughout the State and in all counties and municipalities therein, and no local authority shall enact or enforce any ordinance on the matters covered by this Code unless expressly authorized therein. The Supreme Court noted "thus, unless 'expressly provided' by the Legislature, a City has no authority over vehicular traffic control". The court noted that the principal grant of local authority over traffic control is contained in Vehicle Code Section 21100, which provides among other things that cities may "regulate traffic by means of semaphores or other traffic control devices". Section 21351 gives the right to install traffic control devices necessary to warn or guide traffic, and other statutes grant even more explicit powers including the right to erect stop signs, yield right-of-way signs and to designate all or any. portion of a street for one-way traffic. However, the Court pointed out that Section 21401 provides: "Only those official traffic devices that conform to the Uniform Standards and Specifications promulgated by the Department of Transportation shall be placed upon a street or highway." In the Rumford case the City argued that the term "traffic control devices" was intended to mean signs, signals and other devices that communicate by symbol. However, the court held that if barriers were not "traffic control devices", there was no other authorization to install them, and as "traffic control devices" they have to b'e ones that have been authorized by the Department of Transportation. have installed s~;eeG inquiring of the City Attorneys of those cities as to t~eir theory or basis for their installation they each indicated t~ey were totally unaware of the problem of illegality of such devices on City streets.- One of them also said that the speed bumps in his City had been the alleged cause of some number of accidents. Accordingly, we recommend against-installing speed bumps 'and/or speed humps unless and until such time as they have been approved by the Department of Transportation for use as traffic control devices. City Attorney JGR: se :R: 8/30/88 (1010) cc: WH RLL