Part-Time Transit-Only Lanes

The three-year I-805/SR 94 Part-Time Transit-Only Lanes Pilot Demonstration project (previously referred to as “Bus on Shoulder” allows South Bay Rapid buses to use select road shoulders between National City and Downtown San Diego during peak travel times. It is designed to ensure service reliability and maintain transit schedules. This project is the San Diego region’s first use of transit vehicle-to-infrastructure technology.

Safety is our first priority. Only specially trained MTS drivers on South Bay Rapid buses equipped with driver assistance technology are permitted to operate in the freeway shoulder. Bus drivers will only use shoulders when travel lanes are operating under 35 miles per hour and will never exceed 35 miles per hour in the shoulder. Freeway drivers should remain alert and never follow behind the bus into the shoulder. The shoulders will always be available for law enforcement and emergencies.

A map of San Diego and National City showing the freeways on which South Bay Rapid buses can operate on the shoulder. A dark blue line on SR 94 and I-805 shows the South Bay Rapid route. An orange line on SR 94 West and red lines on I-805 North and SR 94 East shows where the bus is allowed to use the shoulder.

South Bay Rapid buses can operate on these freeway shoulders during heavy traffic congestion.

Sensors embedded on these buses monitor the lanes and provide audio and visual alerts to the bus drivers to help avoid potential conflicts between the buses, other vehicles, or obstructions along the corridor and shoulder.

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Lane Departure Warning: Sensors will notify the bus driver when they are moving toward the edge of the lane.

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Forward Collision Warning: A sensor that will notify the bus driver when they are at risk of a front collision.

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Blind Spot Warning: On-bus technology will alert the bus driver when a vehicle is in the blind spot area.

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Ramp Metering Transit Priority System: A system on the bus that communicates with the ramp metering system to give the bus priority over the cars entering the roadway from a metered on-ramp.

Program Details

Start date: summer 2022

Operations: weekdays only, 6-9 a.m. (northbound I-805 and westbound SR 94) and 3-7 p.m. (eastbound SR 94 and southbound I-805 connector)

Funding: Federal Transit Administration and TransNet

Alignment with state and regional priorities: This project aligns closely with the California Transportation Plan 2050, the Climate Action Plan for Transportation Infrastructure (CAPTI), and SANDAG's 2021 Regional Plan.

Project Partners

Caltrans
MTS