This summer, High Speed Rail Authority is going to re-start planning for blended service on the Peninsula corridor between San Jose and San Francisco.  The planning process will cover the service plan for blended service, upgrades including passing tracks to enable higher speed on the corridor, and changes to stations.

This planning process can help answer some important open questions about how to implement platform compatibility with High Speed Rail.

Even when Caltrain places its car order, there will still be open questions about the car design that affect the compatibility decision.  It seems likely that Caltrain and High Speed Rail will defer the decision about whether to have compatible platform height with high speed rail – boarding at a high 50” level – only at the shared stations, or at all stations.  To do this, Caltrain can order cars with 25″ doors, and “ghost doors” that can be added to be compatible with High Speed Rail’s high platform where and if needed.

If Caltrain provides compatible high-level boarding only at the shared stations, then Caltrain will need to maintain two sets of doors, one for boarding at high-platform stations and one set at low-platform stations.  (This is done for example in the Northeast corridor).  The problem is that trains supporting two platform heights at the same time have fewer seats.

If Caltrain provides compatible level boarding at all stations, then Caltrain will be able to restore seats after a transition period. With high-platform level boarding, passengers will be able to enter the car without stairs, but will then need to use internal stairs to go up to a higher level or down to a lower level.  Passengers with bikes will need to go down internal stars to store bikes.

The major benefits of level boarding (in addition to better accessibility for disabled passengers) is shorter dwell time – less time for the train to be stopped at the station while passengers get on and off. This adds up, and could make travel time significantly faster. But if there are bottlenecks with passengers navigating internal stairs, that could reduce the dwell time benefit.  Can Caltrain test car designs to reduce the dwell time impact of internal stairs?

Also, level boarding at all stations would logically improve reliability – if there is a stoppage on the line, a High Speed train wouldn’t need to back up from San Mateo back to Diridon, but could stop at any station.  How much would this emergency flexibility materially benefit service?

The good news is that the planning about to start for High Speed Rail and Blended service, and Caltrain’s planning for car design, could help answer the open questions, and lead to a more informed decision about whether to provide compatible platforms at some or all stations.

Here’s a list of platform compatibility scenarios, showing where the High Speed Rail and Caltrain planning process could generate  evidence that to help evaluate the compatibility options. For purpose of completeness, we’ve included a logical option that does not provide any platform compatibility.