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The Green Caltrain blog is sponsored by BayRail Alliance, an all-volunteer non-profit organization supporting green rail transit in the Bay Area. This blog and BayRail have no affiliation with Caltrain.


Fixing the mismatch between the San Francisco Downtown Extension and the Blended System

As the planning for Caltrain modernization and the Blended System gets under way, one of the topics to address is the mismatch between the blended system, and the older design of the Downtown Extension (DTX), extending the Caltrain tracks from 4th and King to Downtown and the Transbay Terminal, which predates the blended system.

The high level design for DTX includes 4 tracks for HSR and only 2 for Caltrain, supporting up to 6 trains per hour for HSR and only 4 trains per hour for Caltrain.

But the blended system, even with passing tracks, will support only 4 high speed trains per hour. In the older plan, 60% of Caltrain service is expected to terminate at 4th and King, even though the major demand is downtown.  High Speed Rail doesn’t have 4 tracks anywhere else.

Caltrain electrification is scheduled to be complete in 2019 and High Speed Rail is not expected to get to the Peninsula til 2029 at the earliest. Depending on when DTX is done, Caltrain service would be hampered in advance for years, with no high speed trains in sight.

There are other compatibility and design issues with DTX that Clem Tillier and others have been pointing out over time, such as platform heights, track curvature, passenger flow issues, and more.

This is Clem Tillier’s classic article about the issues with DTX/Transbay.

Now that the Blended System is the agreed approach, how will the the project be updated to take the blended system into account? Can fixes also result in cost savings?

Now that planning is getting under way, it would be great to have updated plans that fix the mismatch.


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  • Calendar of events

    • November 5, 2014

      SamTrans Board meeting

      Starts: 2:00 pm

      Location: 1250 San Carlos Ave., San Carlos, CA

    • November 6, 2014

      Caltrain JPB meeting

      Starts: 10:00 am

      Location: Location: 2nd Floor Auditorium San Mateo County Transit District 1250 San Carlos Avenue, San Carlos

    • November 11, 2014

      TJPA CAC Meeting

      Starts: 5:30 pm

      Location: 201 Mission Street, Suite 2100 San Francisco, CA

    • November 13, 2014

      TJPA Board Meeting

      Starts: 9:30 am

      Location: City Hall, Room 416, 1 Dr. Carlton B. Goodlett Place, San Francisco, CA 94102

    • November 19, 2014

      Caltrain CAC meeting

      Starts: 5:30 pm

      Location: Location: 2nd Floor Auditorium San Mateo County Transit District 1250 San Carlos Avenue, San Carlos

    • November 20, 2014

      Caltrain BAC meeting

      Starts: 6:30 pm

      Location: 1250 San Carlos Avenue, San Carlos, CA

      Description: Bicycle Advisory Committee

    • December 3, 2014

      SamTrans Board meeting

      Starts: 2:00 pm

      Location: 1250 San Carlos Ave., San Carlos, CA

    • December 4, 2014

      Caltrain JPB meeting

      Starts: 10:00 am

      Location: Location: 2nd Floor Auditorium San Mateo County Transit District 1250 San Carlos Avenue, San Carlos

    • December 9, 2014

      TJPA CAC Meeting

      Starts: 5:30 pm

      Location: 201 Mission Street, Suite 2100 San Francisco, CA

    • December 11, 2014

      TJPA Board Meeting

      Starts: 9:30 am

      Location: City Hall, Room 416, 1 Dr. Carlton B. Goodlett Place, San Francisco, CA 94102