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Home My WebLink About2007-05-07; Traffic Safety Commission; ; Establish a prima facie speed limit upon Impala Drive from Palmer Way to Orion Street( CITY OF CARLSBAD TRAFFIC SAFETY COMMISSION STAFF REPORT COMMISSION MEETING OF: May 7, 2007 LOCATION: Impala Drive, Palmer Way to Orion Street INITIATED BY: Jack Missett, 2460 Impala Drive, Carlsbad, CA 92010 ITEMN0.6B REQUESTED ACTION: Establish a prima facie speed limit upon Impala Drive from Palmer Way to Orion Street BACKGROUND: No prima facie speed limit has been established on Impala Drive. The road has existed more than twenty years and was constructed as part of the Palomar Woods Business Park. SETTING SPEED LIMITS: Optimal 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 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. Most drivers operate vehicles in a reasonable manner. Traffic laws established on the basis of the behavior of the reasonable and prudent motorist are found to be the most successful. Roads in Carlsbad are designed in accordance with engineering standards to satisfy the goals of a safe roadway and to enhance efficient traffic flow. One way to achieve the goals is to establish proper and reasonable speed limits that can be enforced. Speed limits that are reasonable can help to 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 arbitrarily restrict travel by the majority of motorists can lead to wholesale violations of the posted speed limit. In the City of Carlsbad, the predominant practice for managing speed is by legally establishing a prima facie speed limit and then posting the speed limit upon the road with regulatory signs. A prima facie speed limit recognizes that conditions change throughout the day and there is no one safe speed for all the conditions that may be present upon the roadway. Police enforcement is used to target the most egregious violators of the speed limit. A fundamental tenet is that laws are enacted to protect the majority of the public by regulating the unsafe or unreasonable actions of the few . ( \ CITY OF CARLSBAD TRAFFIC SAFETY COMMISSION STAFF REPORT COMMISSION MEETING OF: May 7, 2007 ( continued) ITEMNO. 6B Nationally recognized vetted practices and guidance per standards and procedures in the Federal Highway Administration's national Manual on Uniform Traffic Control Devices 2003 Edition are considered when setting speed limits. In California, this manual is titled the California Manual on Uniform Traffic Control Devices. The most common method of establishing speed limits incorporates traffic engineering principles and other factors, such as using the results of a speed survey, into the Traffic and Engineering Survey. Prima facie speed limits are established by law when the City Council adopts an ordinance and the speed limit is posted on the roadway to indicate the maximum reasonable speed for a driver to operate a vehicle under ideal conditions in off-peak free flowing conditions. Among many factors, the three most persuasive arguments to consider when setting a realistic, or rational, speed limit are: 1. Critical speed (85th percentile speed) 2. Collision history 3. Conditions that may not be readily apparent to the driver The premise implied in sgeed zoning is that the majority of drivers are operating their vehicles at or near the 85 percentile speed. Drivers that operate their vehicle at speeds higher than the 85th percentile speed should be the focus of the police. An important speed zoning concept is that the disparity in speed between vehicles on the road is reduced when prima facie speed limits are established at or near the 85 th percentile speed and, as a result, safety is enhanced. Also, a speed limit that is established based upon the 85th percentile speed will increase driver respect for the speed limit sign. Only those signs that have the respect of the roadway user will have a positive effect to control traffic. A review of the collision history on a roadway is an important element in the process to establish a speed limit. The review will reveal if there is a high incidence of speed-related collisions on the road at specific locations. Absent a significant collision history attributed to speed, it can be concluded that drivers are operating their vehicle in a reasonable and prudent manner at the speed they chose to drive. The installation of a speed limit sign does not automatically decrease accident rates nor increase roadway safety. Speed limits should not be lowered for conditions that are readily apparent and the speed limit signs are not used as intersection, curve or hazard warning devices. For the unusual conditions or conditions not readily apparent to drivers, appropriate warning signs are installed. Design factors such as the geometric elements of the road, sight distance, or other factors may have a significant impact on the free flowing speed chosen by drivers. This driver chosen speed, in tum, is considered when establishing a prima facie speed limit. I' I . \ ( CITY OF CARLSBAD TRAFFIC SAFETY COMMISSION STAFF REPORT COMMISSION MEETING OF: May 7, 2007 (continued) ITEMNO. 6B 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. Warning signs placed on the roadway can alert drivers to the presence of an unseen or unanticipated condition. As a result, drivers can operate their vehicle in a reasonable and prudent manner by adjusting speed for the condition that may be encountered. 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 determining a realistic prima facie speed limit to establish. 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: Impala Drive is a short industrial street 0.29 miles in length. The road has a curb-to-curb width of 52 feet with no centerline striping. Street lights are provided on both sides of the street and sidewalk exists along only 600 feet of the street. As indicated on Table A, daily two-way traffic volumes range from 1,611 vehicles near Palmer Way to 483 vehicles at Orion Street based upon counts obtained in March 2007. For the two-year period ending February 26, 2007, there was one reported collision on Impala Drive. This collision was a property damage only collision. The primary collision factor was a violation of right-of-way when an eastbound driver on Impala Driver turned to a driveway on the north side of Impala Drive in front of a westbound vehicle that was unable to stop to avoid the collision. Nine driveways serve the light industrial and office businesses that have ingress/egress to Impala Drive. ( ( CITY OF CARLSBAD TRAFFIC SAFETY COMMISSION STAFF REPORT COMMISSION MEETING OF: May 7, 2007 ITEMNO. 6B (continued) TABLE A 24-HOUR TRAFFIC VOLUMES IMPALA DRIVE LOCATION -HOURA 3/08/07 e/o Palmer Way 961 650 1,611 3/08/07 w/o Orion Street 347 136 483 Impala Drive follows a relatively straight alignment. Roadway grades vary between 1.60% and 9.51 %. On-street parallel parking is allowed on Impala Drive. The 85th percentile speed has been determined throughout the United States to generally conform to a safe and reasonable speed limit. The California Manual on Uniform Traffic Control Devices (FHW A's MUTCD 2003 Revision 1, as amended for use in California) 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, as follows: 627. (a) "Engineering and traffic survey," as used in this code, means a survey of highway and traffic conditions in accordance with methods determined by the Department of Transportation for use by state and local authorities. (b) An engineering and traffic survey shall include, among other requirements deemed necessary by the department, consideration of all of the following: (1) Prevailing speeds as determined by traffic engineering measurements. (2) Accident reports. (3) Highway, traffic, and roadside conditions not readily apparent to the driver. (c) When conducting an engineering and traffic survey, local authorities, in addition to the factors set forth in paragraphs (1) to (3), inclusive, of subdivision (b) may consider all of the following: (1) Residential density, if any of the following conditions exist on the particular portion of highway and the property contiguous thereto, other than a business district; (A) Upon one side of the highway, within a distance of a quarter of a mile, the contiguous property fronting thereon is occupied by 13 or more separate dwelling houses or business structures. (B) Upon both sides of the highway, collectively, within a distance of a quarter of a mile, the contiguous property fronting thereon is occupied by 16 or more · separate dwelling houses or business structures. (C) The portion of highway is longer than one-quarter of a mile but has the ratio of separate dwelling houses or business structures to the length of the highway described in either subparagraph (A) or (B). (2) Pedestrian and bicyclist safety. ( ( CITY OF CARLSBAD TRAFFIC SAFETY COMMISSION STAFF REPORT COMMISSION MEETING OF: May 7, 2007 (continued) ITEMNO. 6B Staff completed the Engineering and Traffic Survey (attached) for Impala Drive from Palmer Way to Orion Street. Results of the speed survey, contained within the Engineering and Traffic Survey that was conducted on Impala Drive, are summarized in Table B. TABLEB SPEED SURVEY DATA FOR IMPALA DRIVE 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 located 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. RECOMMENDATION: Upon review of the results of the Engineering and Traffic Survey, the Traffic Safety Coordinating Committee recommends establishing a 35 mile per hour prima facie speed limit upon Impala Drive from Palmer Way to Orion Street. NECESSARY CITY COUNCIL ACTION: An ordinance will be required to be adopted by the City Council to establish the 35 mile per hour prima facie speed limit upon Impala Drive, as recommended. ENTRANCE TO CITY OF CARLSBAD FLEET MAINTENANCE FACILITY NOT TO SCALE LOCATION I I ,, y pALMERW • I I I I I. I I \ \ \ \ \ ( MAP PROPOSED · SPEEDZONE PROJECT NAME PROPOSED SPEED ZONE IMPALA DRIVE -PALMER WAY TO ORION STREET DRA'ttN BY: SCOTT fVANS, CARLSBAD ENGINEERING DEPT. J '27 07 C: TRAFFIC SPEED ZONES SPEED ZONE-IMPALA DRIVE:.DWG EXHIBIT 1 ( CITY OF CARLSBAD ENGINEERING AND TRAFFIC SURVEY STREET: Impala Drive LIMITS: Palmer Way to Orion Street 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. Midblock Accident History: (3/01/05 through 2/28/07) 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 Parkin D. Roadway Factors: Circulation Element Street Classification Length of Segment Roadway Width Number of Lanes Vertical Alignment Horizontal Alignment Sidewalks Driveways Street Li htin Direction: Eastbound/Westbound 4/11/07 400 Feet e/o Palmer Way 35MPH 26 to 36 MPH 83% No Posted S eed Limit 0 1 2.93 (Rate Based on 1,611 Vehicles) 1.89 (2004 Rate for Same Type of Roadway) 483 -West of Orion Street (3/08/07); 1,611 -East of Palmer Way (3/08/07) Stop Sign Control at Palmer Way Light None Striped Parking Allowed on Both Sides Unclassified 0.29 Mi. 52 Feet (Curb-to-Curb) One Lane Each Direction Roadway Grades Vary from 1.6% to 9.51 % Relatively Straight Only 600 Feet of Roadway Frontage Contains Sidewalk Nine Driveways Street Li hts on Both Sides E. Special Conditions: Impala Drive is uncontrolled where it intersects Orion Street to create a 90 degree turn. The location of the entrance driveway to the City of Carlsbad Fleet Maintenance Facility is at this turn and essentially a T-intersection configuration exists. F. Ad"acent Land Uses: Li ht industrial, fleet maintenance facilil , office. G. Remarks/Conditions Not Readily Apparent: The accident rate of 2.93 is higher than expected for an industrial street, however, this is a factor of low volumes on the roadwa . Pedestrians walk in the roadwa due to absence of sidewalks. 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 California Manual on Uniform Traffic Control Devices for Streets and Highways (FHWA's MUTCD 2003 Revision 1, as amended for use in California) with respect to design and prevailing speeds, accident records, pedestrian and bicyclist safety, intersection and driveway spacing, and roadside and traffic conditions not readil a arent to the driver. As eed limit ostin of 35 MPH is found to be a ro riate and ·ustified. ( DATE: 4/11/07 TIME:11 :00AM TO WEATHER: Sunny & Mild ( CITY OF CARLSBAD SPEED SURVEY 2:00 PM TOTAL VEHICLES: CRITICAL SPEED: LOCATION: Impala Drive~400' e/o Palmer Way VEHICLES IN PACE: OBSERVER/RECORDER: M. Rehfeldt/J. Gale PACE SPEED(S): NONE POSTED SPEED LIMIT EASTBOUND DIRECTION OF TRAVEL MPH # % 2: # % %tile % # 65 64 63 62 61 60 59 58 57 56 55 54 53 52 51 50 49 48 47 46 45 44 43 42 41 40 39 38 X 37 X X 36 X X 35 X X X X 34 X X X X X 33 X X X X X X 32 X X X X X X X 31 X X X 30 X X X X X 29 X X X X 28 X X 27 X X 26 X X X X 25 X 24 X 23 22 X 21 1 1 100 2 1 1 1 99 2 1 1 2 2 2 98 2 1 2 4 3 3 96 2 1 2 4 6 6 93 8 4 4 8 9 9 87 10 5 5 10 10 10 78 10 5 6 12 11 11 68 10 5 7 14 14 14 57 14 7 3 6 8 8 43 10 5 5 10 9 9 35 8 4 4 8 5 5 26 2 1 2 4 6 6 21 8 4 2 4 4 4 15 4 2 4 8 7 7 11 6 3 1 2 2 2 4 2 1 1 2 1 1 2 1 1 2 1 1 1 Engineering Department Transportation Division 100 ____ _____;3~5'--____ MPH 83 % ----------- 26 TO 36 MPH ---------- 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 45 44 43 42 41 X 40 X 39 X 38 X 37 X X X X 36 X X X X X 35 X X X X X 34 X X X X X 33 X X X X X X X 32 X X X X X 31 X X X X 30 X 29 X X X X 28 X X 27 X X X 26 X 25 24 23 22 21