Oak Creek Road speed limit reduced to 40 mph

Courtesy illustration.

The speed limit on Oak Creek Road between Flinn Springs Road and Olde Highway 80 has been reduced to 40 mph.

A 5-0 San Diego County Board of Supervisors vote May 22 approved the first reading and introduction of the ordinance to change the speed limit from 45 mph and to certify the new speed limit for radar enforcement, and a 4-0 vote June 5, with Greg Cox at the National Association of Counties conference, approved the second reading and adoption.

The new speed limit for the 1.5-mile segment will take effect July 5.

In order for a speed limit to be enforceable by radar, a speed survey must show that the speed limit is within an adjacent 5 mph increment to the 85th percentile speed.

Periodic recertification, including a supporting speed survey, is required for continued radar enforcement and the Department of Public Works or a DPW contractor typically conducts speed surveys every seven years. The speed limit may be rounded either up or down from the 85th percentile speed.  The speed limit may also be rounded down an additional 5 mph if findings are made that the road has conditions which would not be apparent to a motorist unfamiliar with the road.

In 2011 a speed survey was taken at Towne Lane and the 85th percentile was 49.9 mph with 65.9 percent of the vehicles traveling within a 10 mph pace of 37-46 mph.

Two speed surveys were taken on Dec. 11, 2018, one at Towne Lane and one at Robledo Real Road. The 60 vehicles crossing the speed survey at Towne Lane had an 85th percentile speed of 47.5 mph with 68.0 percent of the drivers within a 38-47 mph pace.  The most common speeds at Towne Lane were 46 mph with eight drivers and 40 mph with seven motorists.

The speed survey at Robledo Real Road measured 63 motorists whose 85th percentile speed was 41.7 mph with 89.0 percent within a 33-42 mph pace.

The most frequent speeds were 35 mph with ten drivers, 36 mph with eight drivers, and 42 mph with seven drivers.

The county’s Traffic Advisory Committee, which reviewed the speed limit March 8, prefers not to have different speed limits for segments less than one mile. The vehicles at the two locations combined had an 85th percentile speed of 44.6 mph with 78.5 percent within a pace of 36-45 mph, and the TAC recommended the 40-mph speed limit for the entire segment with certification of the new speed limit for radar enforcement.

The entire 1.5-mile segment had four reported collisions, including one involving an injury, in the 36-month period from Nov. 1, 2015, to Oct. 31, 2018.  The collision rate of 1.23 per million vehicle miles is slightly higher than the statewide rate of 1.19 for similar suburban two-lane roads with speed limits between 45 mph and 55 mph.

Two other Lakeside road segments were recertified for radar enforcement at their previous speeds May 22, and since no changes to the ordinance were made no second reading was required.

The 45-mph speed limit for the 1.9-mile segment of Los Coches Road between Julian Avenue and Highway 8 Business was retained; the 85th percentile speed of 51.0 mph in the new survey supported a 50-mph speed limit before the conditions not apparent to the motorist were invoked.

The road segment’s 53 collisions including 24 with injury between Nov. 1, 2015, and Oct. 31, 2018, gives the road a collision rate of 1.80 per million vehicle miles and the statewide average for similar suburban conventional three-lane roads is 1.03 per million vehicle miles.

The 0.95-mile segment of Willow Road between State Route 67 and the intersection with Wildcat Canyon Road and Ashwood Street has a 35 mph speed limit which will remain; although the new speed survey had an 85th percentile of 41.7 mph the 25 collisions including seven with injury between Nov. 1, 2015, and Oct. 31, 2018, equate to a rate of 2.99 collisions per million vehicle miles while the statewide average for similar suburban conventional two-lane roads with speed limits under 45 mph is 1.80 per million vehicle miles.


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