Supervisors support lowering McDonald Road speed limit to 40 mph

The San Diego County Board of Supervisors gave support to lowering the speed limit on McDonald Road from 45 mph to 40 mph.

The supervisors’ 5-0 vote Wednesday, Feb. 10, approved the first reading and introduction of the ordinance to reduce the speed limit on McDonald Road between Fallbrook Street and Pepper Tree Lane, while retaining radar certification for that 1.0-mile segment. The second reading and adoption is scheduled for March 3, in which case the lower speed limit would become effective April 2.

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 county’s 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.

The speed limit on McDonald Road had been 40 mph before 2006. The 2005 speed survey had an 85th percentile of 47.6 mph with 67% of drivers within a 39-48 mph pace; the community input was for a higher speed limit with radar enforcement so the board of supervisors raised the speed limit in 2006. The 45 mph speed limit was retained in 2013 when a speed survey found an 85th percentile of 44.0 mph but with only 46.9% of drivers within the 10 mph pace of 34-43 mph.

McDonald Road is a two-lane roadway with centerline striping which prohibits passing. Although the road continues south of Pepper Tree Lane the striping for prevailing traffic is for southbound vehicles to turn left onto Pepper Tree. A 15 mph advisory sign precedes that curve.

The road is 24 feet in width. It is not classified on the mobility element of the county’s general plan.

A traffic survey was taken south of Gerald Way, Oct. 6. The two-way volume of 2,299 vehicles consisted of 1,175 northbound and 1,124 southbound motorists. The heaviest hourly volumes were 216 drivers between 4 p.m. and 5 p.m., 207 motorists from 3 p.m. to 4 p.m., and 191 vehicles between noon and 1 p.m. The morning hour with the highest volume was 7 a.m. to 8 a.m. when 164 vehicles crossed the survey point.

A speed survey was conducted 200 feet south of Gerald Way on Sept. 28 between 9 a.m. and 11 a.m. The 127 vehicles had an 85th percentile speed of 43.4 mph with 73 drivers, or 57%, within a 10 mph pace of 34-43 mph.

During the 36-month period from June 1, 2017, to May 31, 2020, two collisions were reported along McDonald Road. That created a collision rate of 0.80 per million vehicle miles. The statewide average for similar suburban conventional roads two lanes or less with speeds under 55 mph is 1.32 collisions per million vehicle miles. The May 2019 collision between Palomino Road and Pepper Tree Lane was caused by improper turning. Unsafe speed caused a May 2020 collision at the intersection of Gerald Way which resulted in one injury.

The county’s Traffic Advisory Committee unanimously recommended lowering the speed limit during the Oct. 23 TAC meeting.

Joe Naiman can be reached by email at [email protected].