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HomeMy WebLinkAboutTrans 2016-11-07 Item 1D - Discussion - Stop Sign and Crosswalk Guideliness City of Tukwila Allan Ekberg, Mayor INFORMATIONAL MEMORANDUM TO: Transportation Committee FROM: Bob Giberson, PW Directo BY: Scott Bates, Traffic Engineering Coordinator CC: Mayor Ekberg DATE: November 4, 2016 SUBJECTS: Stop Sign and Crosswalk Guidelines ISSUES How do stop signs, crosswalks and speed humps get approved by the City for installation? BACKGROUND Over time, many citizens have requested stop signs, crosswalks, speed humps and speed limit changes in order to control speeding in neighborhoods. The City of Tukwila is required to follow the 2009 Edition of the Manual On Uniform Traffic Control Devices (MUTCD), as adopted by the State in WAC 468 -95 -010. According to WAC 468 -95 -017, "The decision to use a particular device at a particular location should be made on the basis of either an engineering study or the application of engineering judgment." Thus, while the MUTCD provides Standards, Guidance, and Options for the design and application of traffic control devices, this manual should not be considered a substitute for engineering judgment. Engineering judgment should be exercised in the selection and application of traffic control devices, as well as in the location and design of the roads and streets that the devices complement. DISCUSSION Attached are four Institute of Traffic Engineers (ITE) bulletins, based on the MUTCD guidance, describing stop signs, speed humps and speed limits. In summary: Stop signs should only be installed if at least one of these criteria describe an intersection: • A minor road intersects a major road where application of normal right -of -way rule is hazardous • A street enters through a highway or street • The intersection is unsignalized in a signalized area • Combination of high speed, restricted view, and serious accident history indicates a need Four -way stop signs may be warranted by any one of the following: • Where a traffic signal is warranted, multi -way stop control is an interim measure that can be quickly implemented until the signal is designed and installed • Five or more reported accidents within a twelve -month period, based on conditions • Sufficient vehicle volumes in all directions, based on certain conditions w: \pw eng \projects\a- rw & rs projects \traffic calming\info memo stop signs_xwalks_etc bg gl 110416.docx 91 INFORMATIONAL MEMO Page 2 Speed humps are raised areas in the roadway and shouldn't be confused with low speed parking lot speed bumps that are not allowed in the right -of -way due to higher speeds and liability. Speed humps can have benefits to safety, if placed in the appropriate places and manner. Improper speed humps can have detrimental effects like diverting traffic to other neighborhoods, increased noise levels, increased vehicle emissions, increased response time for emergency vehicles, conflicts with school or transit bus operations, hazards for bicyclists and motorcyclists. The City has presented a Traffic Calming Program to Transportation Committee many times in the past and a link is listed below. We plan to have a shorter version of the Traffic Calming Program on the City's website in 2017. Speed limits are set by Ordinance after conducting a speed study, as authorized by RCW 46.61.415. See attached speed limit fact sheet. One of the last speed studies and limit change was presented to Council on August 13, 2012 for Tukwila Int'I Blvd. Crosswalks are analyzed based on national research and best practices including the National Cooperative Highway Research Program's NCHRP Report 562: Improving Pedestrian Safety at Unsignalized Intersections. NCHRP Report 562 recommends 14 pedestrians per hour for a peak -hour evaluation for the installation of a marked crosswalk for speeds that exceed 35 miles per hour and 20 pedestrians per hour for roadways with speeds of 35 miles per hour or less. As the Public Works web page is refined, these documents and related items can be added as a tool for answering common citizen questions and concerns regarding traffic control devices. RECOMMENDATION For information and discussion only. Attachments: Stop Sign (ITE) All Way Stop (ITE) Speed Humps (ITE) Speed Limits (ITE) Reference Documents: 2009 Manual on Uniform Traffic Control Devices (FHWA) http://www.wsdot.wa.gov/operations/traffic/mutcd.htm WAC 468 -95 http://apps.leg.wa.gov/wac/ NHCRP Study 562 - full version http: / /www.trb.org/ Publications /Blurbs /157723.aspx TIB Speed Study (August 6, 2012 Transportation Committee): http: / /tinyurl.com /hm5epzm TIB Crosswalk Study (March 21, 2016 Transportation Committee) http: / /tinyurl.com /jqkdpos Tukwila Traffic Calming Program (March 2008 Transportation Committee) http:/ /records.tukwilawa.gov/WebLink8 /DocView.aspx ?id = 195046 92 w:\pw eng \projects\a- rw & rs projects \traffic calming \into memo stop signs_xwalks_etc bg gl 110416.docx The Institute of Transportation Engineers Traffic Engineering Council presents TIPS on Traffic En nearin Cobocil Stop Signs How do you decide where to install STOP signs? STOP signs are traffic control devices that drivers encounter every day. They impose an inconvenience on the driver that cannot be ignored. Many drivers feel that more or fewer STOP signs are needed depending on the location and the time of day. Since they impose a significant amount of control over traffic, traffic engineers are very selective about STOP sign installation. In order to ensure that the advantages of installing a STOP sign outweigh the disadvantages, and to provide some consistency in the application of STOP signs, four warrants have been developed that define the minimum conditions under which further consideration of a STOP sign is appropriate. Using these warrants, traffic engineers look at an intersection based on various criteria: • Does a minor road intersect a major road where application of normal right -of -way rule is particularly hazardous? • Does a street enter a through highway or street? • Is the intersection an unsignalized one in a signalized area? • Does the combination of high speed, restricted view, and serious accident history indicate a need for a STOP sign? If one or more of these criteria describe the intersection, the traffic engineer then determines if a STOP sign is the best solution for the problem. It is important to note that a STOP sign should not be installed unless it meets one or more of the 93 warrants. However, if an intersection meets a warrant, a STOP sign does not have to be installed. The engineer should consider lesser control of the intersection, such as a YIELD sign, before installing a STOP sign. Some intersections may require a multi - way STOP sign installation as a safety measure. There are three warrants to help determine if multi -way STOP signs are needed at an intersection. The engineer performs the same analysis as that for two - way STOP signs. Many citizens believe that installing a STOP sign at an intersection will control speed along the roadway. However, unwarranted STOP signs can actually create other problems both at the intersection and along the roadway. When unwarranted STOP signs are used, drivers must stop more frequently. Thus, they tend to drive faster between intersections in order to save time. Unwarranted STOP signs also encourage disobedience and the use of alternate, inadequate routes. Properly located STOP signs can have various benefits. Aside from providing orderly traffic movement, they can reduce some types of accidents and allow minor street traffic to enter or cross a major roadway. Thus, before installing a warranted STOP sign, an engineer should determine that the STOP sign will improve the overall safety and /or operation of the intersection. 94 The Institute of Transportation Engineers Traffic Engineering Council presents TIPS on Trof e Endearing Four -Way Stop Signs Why can't we have an all -way stop to reduce accidents? Many people believe that installing STOP signs on all approaches to an intersection will result in fewer accidents. Effects of unwarranted stop signs on driver behavior and safety are difficult to substantiate. Also, there is no real evidence to indicate that STOP signs decrease the overall speed of traffic. Impatient drivers view the additional delay caused by unwarranted STOP signs as "lost time" to be made up by driving at higher speeds between STOP signs. Unwarranted STOP signs breed disrespect by motorists who tend to ignore them or only slow down without stopping. This can sometimes lead to tragic consequences. Generally, every State requires the installation of all traffic control devices, including STOP signs, to meet state standards of the Department of Transportation. The state standards are based on the Manual on Uniform Traffic Control Devices (MUTCD). The MUTCD is published by the U.S. Department of Transportation, is the national standard for traffic control devices. The MUTCD prescribes standards for the design, location, use and operation of traffic control devices. 4`WAY The installation of multi -way stop control must first meet the warrants as set forth in the MUTCD. Any of the following conditions may warrant an all -way STOP sign installation: 1. Where a traffic signal is warranted, multi -way stop control is an interim measure that can be implemented 95 quickly to control traffic until the signal is designed and installed. 2. The occurrence within a twelve -month period of five or more reported accidents of a type susceptible to correction by multi -way stop control. Such accident types include turn collisions, as well as right -angle collisions. 3. Total vehicular volume entering the intersection from all approaches must average 500 vehicles per hour for any eight hours of an average day and the combined vehicular and pedestrian volume from the minor street or highway must average at least 200 units per hour for the same eight hours, with an average delay to minor street vehicular traffic of at least 30 seconds per vehicle during the maximum hour. However, when the 85th percentile speed of traffic approaching on the major street exceeds 40 miles per hour, the above minimum volumes are reduced to 70 percent. STOP signs should not be viewed as a cure -all for solving safety problems but, when properly located, can be useful traffic control devices to enhance safety for all roadway users. 96 The Institute of Transportation Engineers Traffic Engineering Council presents TIPS on Traf c EnC3i ocfl i Speed Humps Can speed humps be installed on my street? A speed "hump" is a raised area in the roadway pavement surface extending transversely across the travel way. Not to be confused with a speed hump, a speed "bump" is a raised area in a private driveway or parking lot. Speed hump dimensions and characteristics vary from agency to agency. They are typically 12 foot long by 3 to 4 inches high and are usually placed across the roadway between intersections. They are typically requested by residents as a means to slow traffic in residential neighborhoods or decrease the amount of "cut- though" traffic. In general, speed humps may: 1. Reduce traffic speeds in the immediate vicinity of the speed humps, 2. Decrease traffic volume, and 3. Reduce accidents in some areas. At the same time, however, speed humps may also have the following detrimental effects: 1. Divert traffic to other neighborhood streets thereby moving the problem rather than solving it, 2. Increase noise level due to vehicle brakes, tires and engine, 3. Increase vehicle emissions due to deceleration and acceleration, 4. Increase response time of emergency vehicles, 5. Conflict with school and transit bus operation, 6. Present a potential hazard to bicyclists and motorcyclists. 97 Most agencies have a Speed Control Plan which either advocates the use of speed humps as a system wide tool to reduce speeds and /or vehicular volumes or eliminates their use unconditionally. When determining whether to install speed humps, the following restrictions may apply: 1. Streets serving transit buses. 2. Streets with daily traffic volumes above some predetermined threshold. 3. Streets designated as collector streets. 4. Rural roads. The Institute of Transportation Engineers has developed a report covering the design and application of speed humps. The report (Guidelines for the Design and Application of Speed Humps) was prepared by the ITE Technical Council Speed Humps Task Force in 1995. It can be obtained by contacting ITE headquarters at 202/554 -8050. 98 The Institute of Transportation Engineers Traffic Engineering Council presents TIPS on Traffic� En n ring Cbb¢ cll n Speed Limits How are speed limits established? In general, the governing body which has jurisdictional control over a roadway has the power to establish the speed limit for that roadway. This is done by adopting a resolution or by passing an ordinance to establish the speed limit. The State's Department of Transportation gives the final authority to establish and enforce the speed limit. SPEED ZONE AHEAD The matter of establishing the posted speed limit for a given roadway is a serious concern for the traffic engineer. It is based in part upon the characteristics of the roadway and its associated design speed. The design speed defines the values used for the design of a particular road and includes elements such as curve radii, stopping sight distance, and lengths of merges and tapers. Speed limits are also established in part by the drivers themselves. In order for a speed limit to be effective, it must be reasonable to the driver. Most drivers tend to regulate the speed of their vehicle relative to traffic, road and weather conditions. For a speed limit to be effective, the majority of the drivers must voluntarily comply with the law. It has been determined that the speed at which 85 percent of the motorists travel is reasonable and safe. The determination of the 85 percentile speed is made by conducting a speed survey of vehicles traveling along the roadway in question during normal operating conditions. Therefore, basing the speed limit upon this 85th percentile speed will insure a higher 99 level of compliance and create a reasonable uniform flow of traffic. Other factors which are also used in making a determination of the posted speed limit include road surface characteristics, shoulder condition, grade (i.e., steepness of the road), roadside development, parking practices, pedestrian activity, and accident experience. Once the engineering study has been completed and forwarded to the proper governing bodies for passage and approval, the required signs are then posted. Their placement and installation conforms to the Manual on Uniform Traffic Control Devices (MUTCD), which serves as the standard for the design, placement and installation of all traffic control devices. Speed limits cannot be posted in excess of legislatively mandated speed limits. From 1974 to 1995, the U.S. Congress also imposed the 55 mph National Maximum Speed Limit (NMSL). In 1995, Congress repealed the NMSL and returned control of maximum speed limits to the states. SPEED LIMIT 70 100