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Home My WebLink About2006-02-06; Traffic Safety Commission; ; Establish a prima facie speed limit upon Glasgow Drive from Edinburgh Drive to Carlsbad Village Drive( CITY OF CARLSBAD TRAFFIC SAFETY COMMISSION STAFF REPORT COMMISSION MEETING OF: February 6, 2006 ITEMNO.6B LOCATION: INITIATED BY: Glasgow Drive, Edinburgh Drive to Carlsbad Village Drive Selma Broadhurst, 4535 Hartford Place, Carlsbad, CA 92010 REQUESTED ACTION: Establish a prima facie speed limit upon Glasgow Drive from Edinburgh Drive to Carlsbad Village Drive BACKGROUND: Glasgow Drive is a two-lane local road traversing a curvilinear alignment between Edinburgh Drive and Carlsbad Village Drive (see Exhibit l). This road is located in the northeast quadrant of Carlsbad in the Calavera Hills development. SETTING SPEED LIMITS: 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. Carlsbad roads are designed using engineering standards to promote the goals of safety on the roadway and efficient traffic flow. One way to achieve the goals is to establish reasonable 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. In Carlsbad, the most predominant practice of managing speed is by legally establishing a speed limit and posting the speed limit upon the road with signs. Police enforcement is used to target the most egregious violators of the speed limit. 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. The three most persuasive arguments for 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 ( ( CITY OF CARLSBAD TRAFFIC SAFETY COMMISSION STAFF REPORT COMMISSION MEETING OF: February 6, 2006 (continued) ITEMNO. 6B 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 results in enhanced safety. Also, a speed limit that is established based upon 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 an effect in controlling 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 speed-related collisions occur in a high incidence on the road at certain locations. Consequently, factors such as the geometric elements of the road, sight distance, or other factors may have a significant impact on the speed chosen by drivers. Absent a significant collision history as a result of 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 speed limit. A number of factors may be considered when establishing a 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 setting a realistic speed limit. 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. ( ( CITY OF CARLSBAD TRAFFIC SAFETY COMMISSION STAFF REPORT COMMISSION MEETING OF: February 6, 2006 ( continued) DATA: ITEMNO. 6B Edinburgh lillll Drive is a residential serving road that opened more than 20 years ago and is 0.40 miles in length. The roadway has a double-yellow centerline stripe with one travel lane in each direction. On-street parallel parking is allowed except on the easterly side of Glasgow Drive approaching Carlsbad Village Drive. Glasgow Drive is controlled with a stop sign at its intersection with Edinburgh Drive and by a traffic signal at its intersection with Carlsbad Village Drive. There are no other intersection controls on Glasgow Drive in the subject road segment. Although it is unclassified on the Circulation Element of the General Plan, Glasgow Drive functions as a local collector road. A collector road has a daily traffic volume capacity range of between 2,000 and 10,000 vehicles. The road follows a curvilinear alignment through a residential area and adjacent to a community park. In accordance with Engineering Department design criteria, the roadway centerline radius on Glasgow Drive exceeds the minimum centerline radius of 300 feet for a collector road. Centerline vertical grades on Glasgow Drive range from 1 % to 8.00%. A traffic count was obtained at two locations on Glasgow Drive on January 4, 2006 to determine the two-way, 24-hour average daily traffic volume. The recent count data is indicated on Table A. 1/04/06 TABLE A 24-HOUR TRAFFIC VOLUMES GLASGOW DRIVE 125' s/o Carlsbad Village Drive Staff conducted a speed survey on Glasgow Drive on January 4, 2006 to determine the critical speed of vehicles. The critical speed, commonly called the 85th percentile, is the 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 used to help determine the appropriate prima facie speed to post upon a roadway. The 85 th percentile speed has been determined throughout the United States 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)." ( CITY OF CARLSBAD TRAFFIC SAFETY COMMISSION STAFF REPORT COMMISSION MEETING OF: February 6, 2006 ITEMNO. 6B ( continued) 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 Glasgow Drive from Edinburgh Drive to Carlsbad Village Drive. Results from the speed survey, included as part of the Engineering and Traffic Survey that was conducted on Glasgow Drive, are summarized in Table B. TABLEB SPEED SURVEY DATA FOR GLASGOW DRIVE Critical Pac • Speed Speed · MPH MPH 1/04/06 100' n/o Middleton Drive NB/SB 34 27-&+il 84 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. Staff has reviewed all of the Police Department collision reports received for the time period from December 1, 2003 to November 30, 2005. No collisions have been reported to the Police Department during this time period on the subject segment of Glasgow Drive. By virtue of Glasgow Drive meandering through a residential area and adjacent to the Calavera Hills Community Park, there are at various times, a substantial number of pedestrians and parked vehicles on both sides of Glasgow Drive. The use of Calavera Hills Community Park results in pedestrians crossing Glasgow Drive to and from parked vehicles located on the easterly side of Glasgow Drive and also to reach the residences located easterly of Glasgow Drive. The curvilinear road results in vehicles being parked on horizontal curves where sight distance could be limited occasionally by the parked vehicles. Activities in the park, such as softball games, sometimes results in an errant softball being hit over the fence. and into the roadway, resulting in pedestrians crossing at midblock locations between vehicles to retrieve the ball. Additionally, there is a small tot lot located on the northerly side of Glasgow Drive near Edinburgh bane IJII. This park also generates pedestrian activity and some vehicle traffic at this location. ( CITY OF CARLSBAD TRAFFIC SAFETY COMMISSION STAFF REPORT COMMISSION MEETING OF: February 6, 2006 ( continued) RECOMMENDATION: ITEMNO. 6B Based upon the results of. the Engineering and Traffic Survey, the Traffic Safety Coordinating Committee recommends establishing a 30 mile per hour prima facie speed limit upon Glasgow Drive from Edinburgh bafle l1iil to Carlsbad Village Drive. NECESSARY CITY COUNCIL ACTION: An ordinance will be required to be adopted by the City Council to establish the 30 mile per hour prima facie speed limit, as recommended. ( LOCATION MAP \ ARTESIAN W'{. PROPOSED SPEED ZONE PROJECT NAME \ \ \ \ \ \ CALAVERA PARK I PROPOSED SPEED ZONE GLASGOW DRIVE ORA WN BY: SCOTT EVANS, CARLSBAD ENGINEERING DEPT. 1/17 /06 C: \ 1RAFF1C\SPEED ZONES\SPEED ZONE-GLASGOW DRIVE.DWG MIDDLETON DR. NOT TO SCALE EXHIBIT 1 ( ( CITY OF CARLSBAD ENGINEERING AND TRAFFIC SURVEY STREET: Glasgow Drive LIMITS: Carlsbad Village Drive to Edinburgh Drive 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: (12/01/03 to 11/30/05) 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 D. Roadway Factors: Street Classification Length of Segment Roadway Width Number of Lanes Vertical Alignment Horizontal Alignment Sidewalks Driveways Street Li htin Direction: Northbound/Southbound 1/04/06 100 Feet North of Middleton Drive 34MPH 27 to 37 MPH 84% No Posted S eed Limit 0 0 None 2.04 (2003 Rate for Same Type of Roadway) 2,909 -s/o Carlsbad Village Drive (1 /04/06); 1,171 -n/o Edinburgh Drive Traffic Signal at Carlsbad Village Drive; Stop Sign Control at Edinburgh Drive Moderate Pedestrian & Bicycle Traffic Due to Adjacent Park No Designated Bicycle Lanes Have Been Striped on the Roadway Parking Allowed on Each Side Except on the East Side Between Carlsbad Village Drive to Artesian Way Unclassified 0.40 Mi. 40 Feet (Curb-to-Curb) One Lane Each Direction Roadway Grades Vary From 1.00% to 8.00% Curvilinear Sidewalk on Each Side One Driveway Serving the Community Park Street Lights on Each Side E. Special Conditions: Travel lanes are separated by a double-yellow centerline between Carlsbad Village Drive and the park entrance/Middleton Drive. F. Ad"acent Land Uses: Sin le-famil and multi-family residential, communit G. Remarks/Conditions Not Readily Apparent: 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 design and prevailing speeds, accident records, pedestrian and bicyclist safety, intersection and driveway spacing, and roadside and traffic conditions not readily a arent to the driver. A s eed limit ostin of 30 MPH is found to be a ro riate and ·ustified. ( CITY OF CARLSBAD SPEED SURVEY _ DATE; 1/04/06 TIME; 2;15 PM TO 3:45 PM -• TOTAL VEHICLES: WEATHER: ..::S.::.un.::.n:..Ly;...:;· &,;..;M.;.;.;i.;.;.;ld;___......._ __ __,.. __ _ CRITICAL SPEED: ( LOCATION: Glasgow Drive~100' n/o Middleton Drive VEHICLES IN PACE: OBSERVER/RECORDER: J. Gale --------'---PACE SPEED(S): NONE POSTED SPEED LIMIT SOUTHBOUND DIRECTION OF TRAVEL MPH # % l: # % %tile % # 65 64 63 62 61 60_ 59 58 57 56 55 54 53 52 51 50 49 4B 47 46 45 44 43 42 41 40 39 38 37 X 36-X X 35. X X 34 X X X X X X 33 X X X X X X X 32 X X X X X X X 31 X X X X X X 30 X X X X X X 29 X X X X 2B X X 27 X 26 X ~ 25 X 24 . - 23 22 21 1 1 100 2 1 2 2 99 4 2 1 2 3 3 97 4 2 2 4 4 4 94 4 2 2 4 ·5 5 90 6 3 6 12 13 13 85 14 7 7 14 12 12 72 10 5 7 14 9 .9 60 4. 2 6 12 9 9 51 6 .3 6 12 13 13 42 14 .7 4 8 10 10 29 12 6 3 6 4 4 19 2 1 2 4 5 ·5 15 6 3 2 4' 3. 3 10 2 1 2 4 4 4. 7 4 2 2 2 3 4 2 1 1 1 2 1 . - Engine~rii,g Department - Transoortation niVi!=j[nn • 100 ~---_.:;_34..;._ ____ MPH 84 % ---------- TO • 37 -----27 MPH NORTHBOUND DIRECTION OF TRAVEL MPH 65 64 63 62 61 60 59 5B -. 57 -· 56 55 54 53 52 51 50 49 48 47 46 45 44 43 42 41 40 X 39 X 38 X 37 X 36 X 35 X X X X X X 34 X X X X 33 X 32 X X X 31 X X X X X X X 30 X X X X X X 29 X 2B X X-X 27 X 26 X X 25 X X 24 X 23 22 21