Photo by thisisbossi on Flickr.

It’d be very expensive to keep the Capital Crescent Trail and the Purple Line in the same tunnel in Bethesda. The Maryland Transit Administration analyzed some options, but there is no silver bullet. The Montgomery County Council will have to make a tough choice between spending a lot of money or taking the trail out of the tunnel.

The Capital Crescent Trail (CCT) runs in a former railroad tunnel under 2 buildings and Wisconsin Avenue in downtown Bethesda. Plans call for building the Purple Line in this tunnel, with a station under the Apex Building and elevators connecting to the Metro.

Officials have long promised to keep the CCT in the tunnel with the Purple Line, but the cost turned out to be much higher than expected.

The MTA looked at a number of alternative approaches:

The original plan: This design, the “locally preferred alternative,” calls for lowering the floor of the tunnel to make room for an elevated CCT above the Purple Line. The Purple Line station would sit under the Apex Building, adjacent to the planned elevator connection to the Red Line.

Don’t keep the trail in the tunnel: Another option would be to create a new trail alignment through Elm Street Park and along Bethesda Avenue. The tunnel would not have to be lowered, and the Purple Line would run alone in the tunnel. The station would be located in the same spot as in the original plan.

Don’t put the Purple Line in the tunnel: The Purple Line could terminate east of the eastern end of the tunnel, letting the trail to remain in the tunnel. Passengers transferring to the Red Line would have to walk approximately ¼ mile to get to the new southern entrance to the Bethesda Metro.

Tear down and rebuild the Air Rights Building: Tearing down the Air Rights Building, above the tunnel, would make it possible to create a wider tunnel and fit the trail and train station side-by-side. It would require a slightly longer walk for transferring passengers than the original plan. It would also cost a lot of money to purchase and demolish the Air Rights Building on the east side of Wisconsin Avenue.

Have a narrower Purple Line through the tunnel: Several alternatives looked at using single track or gauntlet track in the tunnel. Station locations included placement in the original location or farther west in the Woodmont Plaza.

The County Council’s Transportation and Environment Committee will discuss this issue on March 1.

The findings are disappointing to those of us hoped to escape making a very hard decision. All of the new alternatives for keeping the trail in the tunnel would either seriously degrade the level of service and operational capabilities of the Purple Line, or have an unreasonable cost.

The MTA draft report could do a bit more to persuade everyone by giving more details about why they rejected some alternatives. For example, the report says that operational models showed that the reduced transitway width alternatives didn’t work, especially since the Bethesda station will be the end of the line.

But the report gives no information on the method and assumptions behind the simulations. It would be easier to accept the conclusions if they made those available for review. In any case, the MTA is likely right about this. I can find no examples of successful single-track operations for a terminal station with a short headway.

As much as I wish it were otherwise, we are back to the hard choice: either spend a now-estimated $50.9 million and take considerable construction risk to keep the trail in the tunnel in an overhead structure, or develop the alternative surface route across Wisconsin Avenue.

The right choice is to develop the surface route to the fullest extent possible. $50.9 million is simply too much money to spend to avoid one at-grade crossing for the trail. That cost will double the total cost of rebuilding the CCT, putting the whole trail project at much higher risk of being abandoned in these very difficult budget times.

Also, the elevated trail will involve a narrow switchback to climb above the tracks, and then run in a cage above the tracks. This will not be attractive to most trail riders, and certainly not inviting enough to justify spending $50.9 million.

There is also too much risk that digging under the APEX building will destabilize the entire building. The Silver Spring transit center turned into a fiasco because engineers underestimated the risk of a construction method. Nobody wants another mess like that along the future CCT in Bethesda.

Most likely, the council will decide against taking on the cost and risk that comes with keeping the CCT in the Bethesda tunnel. The political blowback from this decision will be intense; some of that has already started in the comments to the Washington Post’s story about this report.

"Save the Trail” advocate Pam Browning and others are advocating for a third option: kill the Purple Line. But they have the tunnel vision that comes with thinking that CCT means “Chevy Chase’s Trail.” They care little about whether the CCT is ever completed into downtown Silver Spring, and would have us obsess about one trail crossing at Wisconsin Avenue while overlooking the many other at-grade crossings east of Bethesda that will be eliminated as a part of the Purple Line project.

A version of this article originally ran at Silver Spring Trails.