Roundabouts for Moss Beach
Saturday, August 4, 2018 at 11:58AM
Lisa Ketcham

The 2012 Hwy 1 Safety & Mobility Studies introduced the concept of roundabouts for improved traffic circulation in Moss Beach. A roundabout at each end of town would calm highway traffic without stopping it and favor right-turn side-street highway entry with convenient U-turns at each end of town.  

Whatever misgivings people may have had about unfamiliar roundabouts seemed to evaporate when two traffic signals were proposed for Moss Beach (at California and Cypress) in the 2016 draft Connect-the-Coastside recommended transportation improvements.  That year MCC asked Supervisor Horsley to support roundabouts instead of signals in the Midcoast. He agreed and has followed through.  A revised final draft transportation plan from Connect-the-Coastside is due for public review late summer/early fall 2018.  

Cypress/Hwy 1 Intersection Control Evaluation by County traffic consultants DKS used traffic data gathered in June 2017, showing that existing conditions already meet the signal warrant at Cypress, without the Big Wave Project:

“As evidenced by current operating conditions, the two-way stop control at Cypress Avenue and Highway 1 is failing to meet demand and operate in a safe and efficient manner. A multi-lane roundabout will better improve operations, increase safety, and be more contextually sound, as compared to a signal. A single-lane roundabout is the safest alternative, but the limited capacity of the roundabout itself hampers operations along Highway 1 to an unreasonable extent. For these reasons, a multi- lane roundabout is the preferred alternative, followed by a single-lane roundabout and signalization. The “no-build” alternative, keeping the current two-way stop control, is the worst alternative now and in the future, in terms of both operations and safety.” 

California/Hwy 1 intersection analysis (Kittelson July 2018, Table ES 2) indicates peak-hour existing conditions at 2-way stop-controlled California Ave are Level of Service (LOS) F.  Roundabout or signalization would improve the peak hour LOS to A or B.  

Modern roundabouts:

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