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16th Street train trolley connection

written by andy on

Caltrain electrification is the most significant project for the system in its history, and also one of the transformational transportation projects on the Peninsula and Silicon Valley. This project has taken more than a decade to plan. As Caltrain and parallel highways are becoming more congested, this project is needed more than before to increase corridor capacity, despite the fact that Caltrain may have to reduce service to accommodate construction.

Beyond the basic proposal to string overhead wires and buying electric railcars.  There are also related elements where there’s no consensus, no decision, or no funding to complete, but are complementary to electrification. These include level boarding, high speed rail blended service, downtown extension, and grade separations. These elements, regardless of which stage of planning they are in, generally do not impact with the timetable for electrification.

But there is a single unresolved element at the northern end of the corridor that could impact with Caltrain electrification. There ought to be questions whether this element is really necessary or whether it should be deferred.

For more than a decade, Muni has proposed to re-route the 22-Fillmore trolley bus from 18th Street in Potereo Hill to 16th Street and serve the new developments in Mission Bay. Currently 16th Street crosses the Caltrain tracks at grade. In order to re-route the trolley bus service, Muni would have to extend the overhead wires along 16th Street and through the rail crossing. However, to implement transit service along the 16th Street sooner, Muni has instituted route 55 in Jauary 2015, which operates along 16th Street between BART and Mission Bay with hybrid buses.

The unresolved issue is the overhead crossing between the trolley bus and Caltrain. Muni and Caltrain have incompatible electrification standards (600VDC for Muni, 25kV AC for Caltrain). Adding to the issue is the lack of proven solution for the overhead crossing at mainline railroads. In the United States, there are only 5 transit systems that have trolley buses, which all but one also have electrified rail lines, but none of them feature trolley bus lines crossing at grade with electric commuter rail.

Because the trolley bus project has received environmental clearance before Caltrain electrification, Caltrain has taken the primary role to resolve the issue, and has included this overhead crossing as part of the electrification RFP. However regardless of which agency is in charge, there’s no off the shelf solution.

According to Caltrain EIR:

Two feasible options for the SFMTA at-grade trolley crossing at 16th Street underneath the I-280 viaduct have been identified, both of which would involve a short phase break of the Caltrain OCS. Both options would include a short gap in the Caltrain OCS to allow the ETB OCS to be installed through the intersection. The short section of the ETB OCS would not be energized to avoid any potential for contact between energized parts of the Caltrain OCS and the ETB OCS. The options for equipment to facilitate Caltrain operations through the Caltrain OCS gap are as follows:

  • Option #1: Installation of a track-mounted transponder that automatically communicates with special on-board equipment to open the main circuit breaker and preclude current from reaching the car.
    • As a Caltrain consist approaches the 16th street crossing, the engineer would reduce the power draw and the track-mounted transponder would instruct the individual car to open its main breaker. Power drawn from pantographs outside the “zero-power zone” will allow the train to move through the crossing without slowing down. After clearing the crossing, the main breaker will close, and the power draw can be ramped up again.
    • Electric Trolley Buses will operate normally at the crossing, as the collector poles glide along the contact wires up to 6” above the 25kV Caltrain OCS wires. Buses will encounter a roughly 6-foot-long (the width of the Caltrain pantograph) non-energized portion of contact wire at the crossing of each track, but can coast through that gap on a continuous wire structure. This type of movement is a part of normal operations in San Francisco.
    • This type of OCS wire structure has been used previously in Seattle and in Europe.
  • Option #2: Installation of a vacuum circuit breaker (VCB), which removes the requirement for special on-board equipment.
    • The VCB solution has only been available for about 15 years and has not been implemented on a large scale yet. This solution has been utilized in newer installations in China.

Also as acknowledged in the EIR, any arrangement for such crossing would have to be approved by regulating agencies such as the CPUC. A competent regulating agency should ask Muni and Caltrain why such overhead crossing is necessary, and that such arrangements needs to be proven safe, not just simply being feasible and not demonstrated to be unsafe.

I believe there are safety issues with trolley bus crossing with mainline electrified railroad. Trolley bus is prone to poles detaching from the overhead wires. If that happens at or near the crossing, the bus and/or surrounding vehicles would be in danger of getting hit by trains.

While there are several trolley bus/rail overhead crossings in San Francisco and Seattle, in all of these situations the bus and light rail vehicles operate at street speed and have short braking distance. The risk of collision is low. Mainline trains run at a higher speed and have a much longer braking distance.

Running trolley bus through at grade crossing can also put Muni employees at risk by potentially having to detach or re-attach trolley wires within close proximity to the railroad tracks and overhead lines. The safety distance required for high voltage line such as Caltrain is farther than lower voltage lines like Muni.

Alternative to running the trolley bus is already implemented now. The only downside with the 55 line is the necessity to transfer if you want to get off somewhere on the 22 line. If the goal is to have zero emission transit in Mission Bay, battery powered buses will suffice without unique solutions and safety hazards of having buses to “coast through” the tracks where trains won’t have enough distance to stop.

Another alternative is to simply extend the 22 line from 18th Street to Mission Bay. There are only two stops along 16th Street where they will not be served under this scenario.

In addition, San Francisco is currently studying options to remove the I-280 viaduct as well as realigning the railroad. If this is implemented, Caltrain tracks would be grade separated at 16th Street. This is a complicated project because it involves multiple related elements, and may well take a decade or two to complete. If trolley bus service is implemented before the start of this project, it would only complicate the project as temporary detours would also need to have trolley wires.

If the eventual goal is to have 16th Street grade separated, is it worth all the effort to create a custom overhead crossing, especially a solution that requires the use of special onboard equipment?

Regulating agencies like CPUC really doesn’t care about timelines or efficiency. If Caltrain continues to pursue the overhead crossing, there’s a risk that the entire electrification project be put on hold, given the high standard needed to demonstrate safety.

The “safest” strategy, whether it is physical safety, or to ensure project be completed with the least risk, is to defer the 22 line trolley bus on 16th Street until the grade separation is completed. In the meantime, if it is necessary to operate zero emission vehicles, Muni can operate battery powered buses on the 55 line. The battery bus technology may not have been mature when the original study was done recommending the trolley bus extension, but the technology has improved over the years. Transit agencies including Muni may eventually be required to adopt battery bus technology.

Earlier this year, Muni applied for, but did not win, the federal TIGER grant for the 22-Fillmore/16th Street project, which includes trolley wire installation along with other changes to the roadway to speed up service. Perhaps this is not so bad after all (consider that no other projects in Northern California got awarded), since it gives Muni another chance to re-evaluate the project.


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