The three-year Transit Only Lane Demonstration Project allows for South Bay Rapid buses (Route 225), operated by specially trained drivers and equipped with innovative technology, to perform Bus on Shoulder (BOS) operations along I-805 and SR 94 during peak travel times.

Rapid Bus

During heavy traffic congestion, South Bay Rapid buses can operate on selected freeway shoulders between Downtown San Diego and National City, helping bus drivers to bypass slow traffic and maintain transit schedules.  

The project includes the San Diego region’s first use of vehicle-to-infrastructure technology. Sensors embedded on these buses provide audio and visual alerts to the drivers regarding lane position and potential conflicts with other vehicles or obstructions along the corridor and shoulder.

Detailed performance monitoring will document on-time performance data, travel speeds, technology usage, enforcement issues, and rider/driver perceptions of the service. Participating agencies will use this data when planning future projects that include vehicle-to-infrastructure technology.

After the project’s three-year demonstration period, the freeway shoulders will be restored to prior condition.  

Schedule and Budget

Highway construction improvements for the project began in mid-2020 and were completed in summer 2021.  The three-year demonstration project is anticipated to begin operations in fall 2021.

Budget for the project is approximately $30.9 million (including $17 million for new Rapid buses). The project is funded by the Federal Transit Administration and TransNet, the regional half-cent sales tax for transportation administered by SANDAG.


Mass Transit: San Diego region’s Bus on Shoulder pilot program driver training begins (12/10/21)

East County Magazine: Bus on Shoulder Training Begins Along Northbound I-805 and Westbound SR 94 Shoulders (12/7/12)

Time of San Diego: 'Bus on Shoulder' Training Begins Along Northbound I-805 and Westbound SR 94 Shoulders (12/7/12)


Project Fact Sheet EnglishEn Español

Project Map

Frequently Asked Questions

Charter Memo

Decision Document

Concept of Operations and User Needs


MTS bus driver training starts on Monday, December 6, and continues through January! Watch for buses and CHP using the shoulder on I-805 and SR 94, between Downtown San Diego and National City, 6:30 to 8:30am, Monday through Friday. 

Bus On Shoulder billboard

Operations Schedule

BOS Project Map

View Project Map


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