Supervisors support Potter/Elder all-way stop, 35 mph speed limit for all of Gum Tree

Joe Naiman

Village News Reporter

The San Diego County Board of Supervisors approved an all-way stop control for the intersection of Potter Street and Elder Street and a reduction in the Gum Tree Lane speed limit between Hamilton Lane and Live Oak Park Road to 35 mph.

A 5-0 vote June 30 approved the first reading and introduction of the regulatory ordinance changes and a 5-0 vote July 14 approved the second reading and adoption. The stop controls for Potter Street motorists and the lower speed limit on Gum Tree Lane east of Hamilton Lane will become enforceable Aug. 13 although the county's Department of Public Works may place signage earlier.

The action certifies the Gum Tree Lane speed limit east of Hamilton Lane for radar enforcement while recertifying the 35 mph speed limit on Gum Tree Lane between Stage Coach Lane and Hamilton Lane, and the 40 mph speed limit on Hutchison Street in Bonsall between East Vista Way and 1,000 feet west of Harris Drive was also recertified for radar enforcement.

Potter Street and Elder Street are both two-lane roadways with centerline striping which prohibits passing. Both streets are unclassified on the mobility element of the county's general plan, and both streets are considered residential collectors. Elder Street westbound and eastbound motorists currently must obey the stop control at the intersection with Potter Street.

A February 2021 traffic survey at the intersection indicated an average daily volume of 1,990 northbound vehicles on Potter Street, 1,587 southbound vehicles on Potter Street, 1,270 eastbound vehicles on Elder Street, and 652 westbound vehicles on Elder Street.

The intersection collision rate of 0.79 per million vehicle miles was based on five reported collisions, including three involving injury, during the 39-month period between May 1, 2017, and July 31, 2020. The statewide average for similar four-leg intersections controlled by stop signs but not an all-way stop control is 0.24 collisions per million vehicle miles.

The sight distance for eastbound Elder Street motorists at the intersection is 151 feet looking north and 400 feet looking south while westbound Elder Street drivers have a sight distance of 194 feet looking north and 230 feet looking south. At the prevailing speed of 35 mph the public road standard minimum sight distance is 350 feet.

Gum Tree Lane totals 1.49 miles between Stage Coach Lane and Live Oak Park Road including 0.76 miles between Stage Coach Lane and Hamilton Lane. The 35 mph speed limit between Stage Coach Lane and Hamilton Lane was last recertified for radar enforcement in 2013.

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 DPW or a 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. Findings of driveways along the street and pedestrian presence were made to allow the speed limit to be lowered by an additional 5 mph. If speed surveys are taken at more than one location along a reviewed segment a "speed zone" for the entirety of the speed surveys can be used.

Gum Tree Lane east of Hamilton Lane had no posted speed limit, although by state law motorists can travel no faster than 55 mph on a two-lane road which is not a freeway. Without a posted speed limit motorists were able to travel 55 mph on Gum Tree Lane between Hamilton Lane and Live Oak Park Road.

The mobility element designates Gum Tree Lane as a Light Collector west of Hamilton Lane. The segment east of Hamilton Lane is not classified on the mobility element. The 35 mph speed limit becomes 25 mph in the vicinity of William Frazier Elementary School when children are present, and the road also has speed advisory signs prior to curves. The estimated average daily traffic volume by the school is 4,600 vehicles.

During the 36-month period from Feb. 1, 2018, to Jan. 31, 2021, Gum Tree Lane had six reported collisions, including two with injuries. The collision rate of 0.92 per million vehicle miles compares favorably with the statewide average of 1.60 per million vehicle miles for similar suburban two-lane roads with speed limits under 45 mph.

Six reported collisions, including two with at least one injury, occurred during the 36-month period from Oct. 1, 2017, to Sept. 30, 2020. The collision rate of 3.44 per million vehicle miles exceeds the statewide average of 1.60 per million vehicle miles for similar suburban two-lane roads with speed limits less than 45 mph.

On March 12. unanimous votes of the county's Traffic Advisory Committee recommended an all-way stop control for the intersection of Potter Street and Elder Street, a 35 mph speed limit for all of Gum Tree Lane, and recertification of the Hutchison Street speed limit. The March 12 motion did not include an all-way stop control for Gum Tree Lane and Hamilton Lane, although DPW will review the intersection to determine if an all-way stop is warranted.