Supervisors support 30 mph speed limit for Rice Canyon Road, all-way stop at Rice Canyon and Rainbow Heights Road

The San Diego County Board of Supervisors gave their support to a 30 mph speed limit on Rice Canyon Road and an all-way stop control at Rice Canyon Road and Rainbow Heights Road.

The first reading and introduction of the ordinance was approved on a 4-0 vote, Jan. 10, with Greg Cox at a National Association of Counties meeting. The second reading and adoption is scheduled for Jan. 24, and approval on that day would make the speed limit and stop requirement enforceable Feb. 23, although the county's Department of Public Works may post signage earlier.

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. 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. Curves throughout the road, the lack of shoulder lanes and an accident rate above the statewide average for similar roads were cited as conditions which would warrant a 30 mph speed limit rather than a 35 mph speed limit supported by the speed survey.

"Keeping our roadways safe is a priority, so the board voted in favor of the Traffic Advisory Committee's recommendation for a 30 mph speed limit on Rice Canyon Road," Supervisor Bill Horn said. "If the board gives final approval later this month, new speed limit signs will be posted, and there will be radar enforcement to reduce the number and severity of collisions on Rice Canyon Road."

The county's Traffic Advisory Committee unanimously recommended the 30-mph speed limit and all-way stop control during their Oct. 27 meeting.

The distance of Rice Canyon Road between state Route 76 and Eighth Street is 5.06 miles. The road does not currently have a posted speed limit. Currently, a stop sign for southbound traffic exists at state Route 76 and a stop sign for northbound motorists is present at Rainbow Heights Road. Rice Canyon Road ranges in width between 20 and 24 feet and curve advisory warning signs are posted throughout the road, which also has a striped median.

Rice Canyon Road is classified as a "light collector" in the mobility element of the county's general plan, but it also holds the unofficial classification of being a shortcut for Riverside County commuters who desire to avoid Interstate 15, including the secondary border checkpoint by using Rainbow's surface streets.

An Aug. 3 traffic survey taken on Rice Canyon Road, 405 feet south of Moon Ridge Road, revealed a daily count of 1,139 northbound vehicles and 207 southbound vehicles. The volume included 335 northbound vehicles between 4 p.m. and 4:59 p.m. and 356 northbound vehicles from 5 p.m. to 5:59 p.m. The Aug. 29 traffic survey taken at Rainbow Heights Road and Rice Canyon Road produced a daily volume of 1,068 westbound, 1,004 southbound and 823 northbound vehicles. The highest hourly volumes for the westbound vehicles turning from Rainbow Heights Road to Rice Canyon Road were 85 vehicles between 8 a.m. and 8:59 a.m., 84 vehicles from 6 a.m. to 6:59 a.m., 83 vehicles from 7 a.m. to 7:59 a.m. and 82 vehicles between 2 p.m. and 2:59 p.m. The one-hour period between 4 p.m. and 5 p.m. had the highest volumes both ways on Rice Canyon Road with 122 northbound and 105 southbound motorists.

During the 67-month period from Jan. 1, 2012, to July 30, 2017, Rice Canyon Road between state Route 76 and Eighth Street had 38 reported collisions including 18 which involved injury and one which resulted in a fatality. The rate of 2.74 collisions per million vehicle miles exceeds the statewide average of 1.4 collisions per million vehicle miles for similar two-lane roads with speed limits under 55 mph.

National Data and Surveying Services conducted two Aug. 3 speed surveys on Rice Canyon Road. The survey 405 feet south of Moon Ridge Road was taken between 11 a.m. and 1 p.m., and the 59 vehicles had an 85th percentile speed of 38 mph with 76 percent of the vehicles within a 10 mph pace of 29-38 mph. The fastest vehicle traveled at 43 mph, the two slowest motorists crossed the survey point at 25 mph and six motorists apiece made 31 mph and 38 mph the most frequent speeds, while five drivers apiece traveled at 29 mph, 30 mph, 32 mph and 34 mph.

The speed survey 420 feet north of Clearwater Road was taken between 9 a.m. and 11 a.m. and involved 53 vehicles with an 85th percentile of 39 mph and 64 percent of drivers within a 25-34 mph pace. The fastest driver traveled 44 mph, the slowest vehicle had a speed of 21 mph and the most common speeds were 31 mph with six motorists and 30 mph and 28 mph with five motorists apiece.

Rainbow Heights Road, which is not classified in the mobility element, is 20 feet wide at its intersection with Rice Canyon Road, which is 24 feet in width at the intersection. The stop sign only for northbound traffic at the intersection was based on prevailing flow. The increased volume of northbound traffic, in conjunction with a sight distance at the intersection of approximately 100 feet for motorists on Rainbow Heights Road, creates the risk of an accident under the current configuration.

The two collisions at the intersection of Rice Canyon Road and Rainbow Heights Road between Jan. 1, 2012, to July 30, 2017, neither of which involved injury, created a rate of 0.34 collisions per million vehicles crossing; the statewide average for similar intersections is 0.16 collisions per million vehicles.

"An all-way stop at Rice Canyon Road and Rainbow Heights Road will make the intersection much safer for pedestrians, bicyclists and commuters by providing a greater level of right of way assignment," Horn said. "The Traffic Advisory Committee made this recommendation based on the increased traffic in this area and limited sight distance."