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Home My WebLink About2006-05-01; Traffic Safety Commission; ; Establish a prima facie speed limit upon Aston Avenue from College Boulevard to Rutherford Road( ( CITY OF CARLSBAD TRAFFIC SAFETY COMMISSION STAFF REPORT COMMISSION MEETING OF: May 1, 2006 LOCATION: INITIATED BY: Aston A venue, College Boulevard to Rutherford Road Cpl. Michael Bolton, Traffic Division, Police Department ITEMNO.6B REQUESTED ACTION: Establish a prima facie speed limit upon Aston Avenue from College Boulevard to Rutherford Road BACKGROUND: Aston A venue is a two-lane industrial road in the Carlsbad Research Center industrial park development and connects College Boulevard to Rutherford Road (see Exhibit 1). This road is located in the northwest quadrant of the City of Carlsbad. SETTING PRIMA FACIE SPEED LIMITS: A fundamental concept in transportation engineering is that of speed. Mobility is enhanced and overall traffic flow improved when drivers are operating their vehicles at a speed that is reasonable and safe. In fact, the premise of California Vehicle Code (CVC) section 22350, Basic Speed Law, is that no person shall drive upon a road at a speed greater than is reasonable and prudent taking into account weather, visibility, and traffic on the road and in no event at a speed that endangers the safety of others. Roads in Carlsbad are designed using engineering standards to promote the goals of safety on the roadway and to allow efficient traffic flow. One way to achieve the goals is to establish proper and reasonable prima facie speed limits that can be enforced. Speed limits that are reasonable help achieve voluntary compliance by the majority of drivers without need for the presence of a police officer. Laws and/or the establishment of speed zones that restrict travel by the majority of motorists can lead to wholesale violations of the posted speed limit. In the City of Carlsbad, the most predominant practice of managing speed is by legally establishing a speed limit and then posting the speed limit upon the road using regulatory signs. Police enforcement targets the most egregious violators of the speed limit. A fundamental tenet is that traffic laws are enacted to protect the public by regulating the unsafe or umeasonable actions of the few. ( ( CITY OF CARLSBAD TRAFFIC SAFETY COMMISSION STAFF REPORT COMMISSION MEETING OF: May 1, 2006 (continued) ITEMNO. 6B The most common method to establish prima facie speed limits incorporates traffic engineering principles and other factors, such as the results of a speed survey, into the Traffic and Engineering Survey. Posted speed limits are established to indicate the maximum reasonable speed for a driver to operate a vehicle under ideal conditions in off-peak free flowing conditions. Although the influences on speed are complex, the three most persuasive arguments for setting a realistic, or rational, speed limit are the: 1. Critical speed (85 th percentile speed) 2. Collision history 3. Conditions that may not be readily apparent to the driver The premise in speed zoning is that the majority of drivers are traveling at or near the 85th percentile speed. Drivers that operate their vehicle at speeds higher than the 85th percentile speed would be the focus of the police. The disparity in speed of vehicles on the road is reduced when speed limits are established at or near the 85 th percentile speed and this, in tum, results in enhanced safety. Also, a speed limit that is established on the basis of the 85th percentile speed will increase respect for the speed limit sign. Only those signs that have the respect of the roadway user will have a positive effect in controlling traffic. Reviewing the collision history on a roadway is an important element in the process to establish a speed limit. The review will reveal if speed-related collisions occur in a high incidence on the road at certain locations. Consequently, the geometric elements of the road, sight distance, or other factors may influence the speed chosen by drivers. Absent a significant collision history resulting from speed, it can be concluded that drivers are operating their vehicle in a reasonable and prudent manner at the speed they chose to drive. This driver chosen speed, in tum, is used in establishing a prima facie speed limit. A number of factors may be considered when establishing a prima facie speed limit. The 2003 MUTCD lists such factors as: A. Road characteristics, shoulder condition, grade, alignment, and sight distance; B. The pace speed; C. Roadside development and activity; and D. Reported crash experience for at least a 12-month period. As stated, basic speed law requires drivers to operate their vehicle at a speed that takes into account all roadway factors, environmental elements, adjacent land uses, and other traffic on the road. These are, in general, all readily apparent factors. W aming signs placed on the roadway can alert drivers to the presence of an unseen or unanticipated condition. As a result, drivers are able to operate their vehicle in a reasonable and prudent manner by adjusting speed for the condition that may be encountered. ( ( CITY OF CARLSBAD TRAFFIC SAFETY COMMISSION STAFF REPORT COMMISSION MEETING OF: May 1, 2006 ( continued) ITEMNO. 6B In summary, through the use of engineering, educational, and enforcement techniques, the management of vehicle speed is conducted. Voluntary public compliance with the posted speed limit is the goal when setting a realistic speed li:rrut. The realistic speed limit takes into consideration the normally competent and careful actions of a reasonable driver and provides for the regulation of unreasonable behavior by a few individuals. A posted speed limit should be readily accepted by drivers, be fair and reasonable, be related to risk on the roadway, be determined by the majority of drivers, and one that has a factual foundation. DATA: Aston A venue is unclassified on the Circulation Plan of the Circulation Element found in the City of Carlsbad General Plan. However, the roadway functions as an industrial road collector and has a curb-to-curb width of 52 feet. One traffic lane is provided in each direction that is separated by a double-yellow centerline stripe. A bicycle lane striped on each side of the road results in the lack of availability for on-street parallel parking, however, it does facilitate an NCTD bus stop on Aston A venue. A traffic signal controls Aston A venue at its intersection with College Boulevard. On the east end of the street, Aston A venue is controlled with a stop sign at its intersection with Rutherford Road. Pasteur Court and Darwin Court, both of which are cul-de-sacs, intersect Aston Avenue. However, no controls have been placed upon Aston Avenue at either intersection. Centerline roadway grades on Aston Avenue vary from 1.98% to 5.10% with curb and gutter; sidewalks, and street lights constructed on both sides of the roadway. A total of nine driveways are located on Aston A venue. In the two-year period from January 1, 2004 to December 31, 2005, there has been one reported collision. This collision, 130 feet west of Rutherford Road, resulted in an injury due to the primary collision factor of exceeding the safe speed upon the roadway. Prior to January 2004, the last reported collision upon Aston A venue was recorded in July 1996. A traffic count was obtained on Aston Avenue on March 29, 2006 to measure the two-way, 24-hour average daily traffic volume. The recent count data is indicated on Table A. TABLE A 24-HOUR TRAFFIC VOLUMES ASTON A VENUE ( CITY OF CARLSBAD TRAFFIC SAFETY COMMISSION STAFF REPORT COMMISSION MEETING OF: May 1, 2006 ITEMNO. 6B ( continued) Staff conducted a speed survey on Aston A venue on April 4, 2006 to obtain data to calculate the critical speed of observed vehicles. The critical speed, commonly called the 85 th percentile speed, is the free flowing speed at which 85 percent of the vehicles are traveling at or below. A sample of 100 vehicles was measured to determine the critical speed. The critical speed is one factor used to help determine the appropriate prima facie speed to post upon a roadway. Throughout the United States, the 85th percentile speed has been determined to generally conform to a safe and reasonable speed limit. The 2003 Manual on Uniform Traffic Control Devices (MUTCD) California Supplement provides guidance when a speed limit is to be posted. It states that "the speed limit should be established at the nearest 10 km/h (5 mph) increment to the 85th percentile speed. However, in matching existing conditions with the traffic safety needs of the community, engineering judgment may indicate the need for a further reduction of 10 km/h (5 mph)." California Vehicle Code section 627 defines the term "Engineering and Traffic Survey" and lists its requirements. Staff completed an Engineering and Traffic Survey (attached) for Aston A venue from College Boulevard to Rutherford Road. Results from the speed survey, included as part of the Engineering and Traffic Survey that was conducted on Aston A venue, are summarized in Table B. TABLEB SPEED SURVEY DATA FOR ASTON A VENUE ====..,.... The pace speed is the 10 mile per hour range of speeds that contain the highest number of observed vehicles. Generally, the critical speed is in the upper range of the pace speed. Sections 22357 and 22358 of the California Vehicle Code authorize local authorities to establish a prima facie speed limit on the basis of the results of an Engineering and Traffic Survey. The Engineering and Traffic Survey considers such factors as the number of collisions that have occurred on the road segment, roadway features, adjacent land uses, driveway locations, traffic volumes, pedestrian volumes, critical speed, horizontal and vertical alignment, stopping sight distance, and conditions that may not be readily apparent to the driver. ( CITY OF CARLSBAD TRAFFIC SAFETY COMMISSION STAFF REPORT COMMISSION MEETING OF: May 1, 2006 ( continued) RECOMMENDATION: ITEMNO. 6B Based upon the results of the Engineering and Traffic Survey, the Traffic Safety Coordinating Committee recommends establishing a 40 mile per hour prima facie speed limit upon Aston A venue from College Boulevard to Rutherford Road. NECESSARY CITY COUNCIL ACTION: An ordinance will be required to be adopted by the City Council to establish the 40 mile per hour prima facie speed limit upon Aston A venue, as recommended. LOCATION PROPOSED SPEED ZONE NOT TO SCALE DARWIN CT. I ,~ I MAP I I I I \ \ \ \ PROJECT NAME PROPOSED SPEED ZONE ASTON A VENUE DRAl',N BY: SCOTT EVANS, CARLSBAD ENGINEERING DEPT. 4 5/D6 C: TRAmc SPEED ZONES\SPEED ZONE-ASTON AVc.01\U ~(s c~ - G'~ <9(vq EXHIBIT -1 ( CITY OF CARLSBAD ENGINEERING AND TRAFFIC SURVEY ( STREET: Aston Avenue LIMITS: College Boulevard to Rutherford Road A. Prevailing Speed Data: Date of Speed Survey Location of Speed Survey 85th Percentile 10 MPH Pace Percent in Pace Posted S eed Limit B. Mldblock Accident History: (1/01/04 to 12/31/05) Speed-Related Accidents Total Accidents Accidents/Million Vehicle Miles (MVM) California Statewide Accidents/MVM C. Traffic Factors: Average Daily Traffic Traffic Controls Pedestrian/Bicycle Traffic Bicycle Lanes On-Street Parking Other D. Roadway Factors: Street Classification Length of Segment Roadway Width Number of Lanes Vertical Alignment Horizontal Alignment Sidewalks Driveways Street Li htin 1 1 0.74 Direction: Eastbound/Westbound 4/04/06 300 Feet w/o Darwin Court 42MPH 34 to 44 MPH 85% No Posted S eed Limit 2.03 (2003 Rate for Same Type of Roadway) 5,783 -West of Pasteur Court (3/29/06} Stop Sign Control at Rutherford Road; Traffic Signal at College Boulevard Light Bicycle Lane on Each Side Parking Prohibited on Each Side Bus Route Unclassified 0.32 Mi. 52 Feet (Curb-to-Curb) One Lane Each Direction Roadway Grades Vary From 1.98% to 5.10% Curvilinear Sidewalk on Each Side Nine Driveways Street Lights on Each Side E. Special Conditions: This portion of Aston Avenue functions as an industrial road collector and provides access to th_e Carlsbad Research Center, a large industrial park. Travel lanes are separated by a two-way left turn lane. Two streets intersect Aston Avenue. F. Ad acent Land Uses: Li ht lndustrial/Manufacturin G. Remarks/Conditions Not Readll A arent: N.A. H. Traffic Engineer's Recommendation (Explanation): This speed zone satisfies the conditions of Section 627 of the California Vehicle Code and has been prepared and evaluated in accordance with the Manual on Uniform Traffic Control Devices (MUTCD) 2003 Edition as amended by the MUTCD 2003 California Supplement with respect to desi,gn and prevailing speeds, accident records, pedestrian and bicyclist safety, intersection and driveway spacing, and roadsicfe and traffic conditions not readily a arent to the driver. As eed limit ostin of 40 MPH is found to be a ro riate and ·ustified. ( DATE: 4/04/06 TIME: 9:20 AM WEATHER: Sunnl& Mild TO CITY OF CARLSBAD SPEED SURVEY 10:30 AM TOTAL VEHICLES: CRITICAL SPEED: LOCATION: Aston Avenue~300' w/o Darwin Court VEHICLES IN PACE: OBSERVER/RECORDER: J. Gale WESTBOUND DIRECTION OF TRAVEL MPH 65 64 63 62 61 60 59 58 57 56 55 54 53 52 51 50 49 48 47 46 X 45 X X 44 X 43 X X X 42 X X X X 41 X X X 40 X X X X X X X X 39 X X X X 38 X X X 37 X X X X 36 X X X X 35 34 X X X X 33 X X 32 X X 31 X 30 29 28 27 26 25 24 23 22 21 PACE SPEED(S): NONE POSTED SPEED LIMIT # % I:# % %tile % # 1 2 2 2 100 2 1 2 4 2 2 98 1 2 3 3 96 4 2 3 6 5 5 93 4 2 4 8 9 9 88 10 5 3 6 4 4 79 2 1 8 16 13 13 75 10 5 5 10 14 14 62 18 9 4 8 9 9 48 10 5 5 10 9 9 39 8 4 5 10 13 13 30 16 8 3 3 17 6 3 4 8 6 6 14 4 2 2 4 4 4 8 4 2 2 4 3 3 4 2 1 1 2 1 1 1 Engineering Department Transportation Division 100 42 MPH 85 % 34 TO 44 MPH EASTBOUND DIRECTION OF TRAVEL MPH 65 64 63 62 61 60 59 58 57 56 55 54 53 52 51 50 49 48 47 X 46 45 X X 44 X X 43 X X X X X 42 X 41 X X X X X 40 X X X X X X X X X 39 X X X X 38 X X X 37 X X X X X X X 36 X X 35 X X 34 y. X 33 X 32 31 30 29 28 27 26 25 24 23 22 21