Lafayette commission backs one speed hump on Glenside Drive, urges council to fund construction

On April 21, 2025, the City of Lafayette Transportation and Circulation Commission voted unanimously to recommend construction of a single speed hump on Glenside Drive between St. Mary's Road and the Lafayette-Moraga Trail and to ask the City Council to authorize funding from the traffic calming sinking fund to design and construct the feature.

Staff told the commission that the western segment of the Glenside Drive loop carries about 2,300 vehicles per day and lacks formal sidewalks on the block under consideration. Data collected for 48 hours on weekdays while school was in session show 80th-percentile speeds of about 31 mph eastbound and 33 mph westbound on a street with a 25 mph limit. Staff reported roughly 79% of eastbound and 85% of westbound vehicles exceeded 25 mph; about 25% eastbound and 36% westbound exceeded 30 mph.

The commission's action implements the staff recommendation to install one speed hump sited to meet sight-distance requirements and to avoid driveways and utilities. Staff described typical local speed-hump dimensions (about 3 to 3.5 inches high with ramp lengths of 3 to 6 feet, 6 feet standard) and said the hump would complement an existing raised crosswalk to the east and two speed humps installed earlier on the corridor.

"In short, because they are the most effective and affordable means to promote consistent and slower speeds along a segment of roadway," staff said in explaining the choice of speed humps. The staff presentation cited a 2023 Burton Valley pilot evaluation and an earlier San Francisco Municipal Transportation Agency study as local and regional evidence that humps reduce 80th-percentile speeds and greatly reduce the number of vehicles traveling over 30 mph.

During public comment, resident Peter Deroldt said he has lived on the block 16 years, walks dogs on the nearby trail and has called police several times over fast drivers. "It just blows my mind how fast they're going sometimes," Deroldt said, describing one confrontation in which a driver backed into his garbage cans and yelled at him. He said he collected neighborhood signatures and that about 82% of fronting households signed the traffic-calming application.

Commissioners asked staff to clarify program boundaries, funding and a typographical error in the report (the staff report used "Glen Road" in one spot). Staff confirmed the city has funding available in the traffic calming sinking fund but noted the two projects in the current cycle would tap most of this year's allocation. The commission approved two recommendations by voice vote: construct the proposed speed hump and forward the recommendation to the City Council to authorize sinking-fund funding for design and construction. The motion was moved and seconded and passed with all commissioners voting "aye." (Commissioners present at roll call: Stella Weatherspoon; Greg Brown; Lynn Hedain; Michelle Sahar; Chair Bart Carr.)

After the vote commissioners resumed a policy discussion about speed cushions, smaller, segmented vertical devices designed to allow wider-wheelbase emergency vehicles to straddle the device. Staff said cushions can reduce speeds but may be perceived as less effective by residents; they described tradeoffs including placement where there is truck traffic or emergency-route considerations and referenced Caltrans guidance and the SFMTA experience. Staff agreed to include speed cushions among options considered in future requests but recommended consistency with existing speed-hump installations on the Glenside corridor for this project.

The commission's recommendation will be placed on an upcoming City Council agenda for final approval; staff said engineering would complete design and move to implementation if council authorizes funding. No final construction timetable was specified at the meeting.