Silver Spring Trails

01/13/2010 update: The Gazette reports on the position MTA took on this issue at a Jan. 7 meeting with the Town of Chevy Chase. Among the MTA positions – their noise predictions indicate the Purple Line noise will not rise above the ambient noise at the town, and changing sides will make little difference. MTA believes the trail will not be elevated to be higher than rail at the Town if the trail is on the south side. The Town continues to push to have the trail on their side to give them easier access, with no attention being paid to this coming at the expense of ease of access for their neighbors on the other side.

(Posted on 01/03/10, revised on 01/10/2010)

Would the future CCT be a better trail if it is moved south? I don’t mean moving it south to a warmer climate – though right now I wish we could. I mean moving it a few feet south, to be on the south side of the Purple Line light rail in the Georgetown Branch Corridor instead of on the north side as is now proposed.

This issue was raised by residents of the Town of Chevy Chase and Edgevale at the Purple Line Master Plan public hearing on December 10, 2009. They argued that having the trail on the south side would give them easier access to the trail. They live on the south side of the corridor, and they want to keep their back yard gates that open directly onto the trail. If the rail is on the south side of the corridor, it will block their private access to the trail. They want the Master Plan draft to be changed to have the trail on their side, or at least to have the issue be seriously studied.

Should trail users support delaying the Master Plan approval while this can be closely examined? Delaying the Master Plan would be disruptive to the Purple Line design process, but if trail users stand to gain substantially by “flipping” the CCT to the south side then a delay for further study should be considered.

The part of the trail that could be “flipped” from the north side to the south side of the corridor is between Bethesda and Jones Mill Road. The remainder of the trail in the Georgetown Branch is already planned to be on the south side.

THE BOTTOM LINE: The trail will be better overall, by a small margin, if on the north side as now planned. The small differences do not merit disrupting the design process to open a new study. MTA has been briefing the community regularly for over 2 1/2 years to show their plans to have the trail on the north side, and those who are just now coming late in the process to demand we reconsider have not met their burden to show substantive reasons to delay the design to study this yet again. I say this up front for those who are put to sleep by Purple Line planning details. If you are interested in planning and/or think I am wrong, then you can read on and challenge my thinking by commenting.

The side the trail is on will have several impacts:

1. The ease of access for residents living on either side
2. The distance from the rail to adjacent homes on either side
3. The need to have a trail crossover
4. How the trail and rail share the East-West Highway underpass
5. Vertical separation between trail and rail

1. Ease of access: An even trade-off

Public access to the trail will be provided from both sides by formal access points at regular intervals along the trail: from Elm Street Park and Pearl Street at Chevy Chase, at the Sleaford Road path in East Bethesda, at Connecticut Ave., and at Jones Mill Road. The access from these points will not be impacted much by changing the side the trail is on, because these access points will be where there is a grade separated crossing above or below the transit tracks.

Two other public access points now along the trail will be impacted by which side the trail is on: The neighborhood path at Lynn Drive at the Town of Chevy Chase, and the access path from Kentbury Drive in East Bethesda near the Country Club, shown at right. If the trail is on the north side, then residents of Chevy Chase must cross the tracks at grade to reach the trail on the Lynn Drive Path – not a big problem since good design can give a safe crossing, see Keeping the children safe. If the trail is on the south side, then the residents of East Bethesda will lose this access path from Kentbury Drive – not a big problem with the Sleaford Road access path not far away. Both East Bethesda and the Town of Chevy Chase have about the same number of residents, both inconvenienced slightly if their “side” loses. Overall, publc access to the trail is about an even trade-off for a north or a south side trail.

In addition to these public access paths, there is private access from back yard gates along both sides of the trail. Access from these private properties will be blocked on the side that will be next to the rail – currently planned to be the south side. When I walk the trail and count the back yard gates, informal stair cases, and foot bridges that people use to access the trail from private property from either side, I cannot see any clear advantage to access from private property of having the trail on north or south side. The number of impacted private access points is about equal on either side. I do not believe those who are raising the issue of losing their private access can show that protecting the privilege they enjoy on their side is more important than that of their neighbors on the other side. Access from private property is roughly an even trade-off for a north or a south side trail.

I have heard Purple Line opponents argue that we should oppose any plan that will reduce the access to the trail from the neighbors with back yard gates. As a resident of Woodside, one of the several whole neighborhoods in Silver Spring that is still waiting for the trail after all of these years, I find that argument to be silly. Completing the trail into Silver Spring with the Purple Line will give access to the trail from thousands of homes east of Rock Creek that do not have any reasonable trail access now. This far outweighs the importance of protecting the back yard access for a few privileged homes in Chevy Chase.

2. The distance between rail to the adjacent homes: An even trade-off

Several homes in the Town of Chevy Chase and Edgevale have been built close to the Georgetown Branch Corridor and are drawing attention as being heavily impacted by the Purple Line light rail. The several homes most impacted are on either side of East-West Highway, and can be seen in the aerial photo below.

View Larger Map

It is argued that if the trail is flipped to the south (east) side, then the homes will be adjacent to the trail instead of the rail, and this increased separation between the homes and rail will be significant in reducing the noise impact from the transit vehicles.

But if the trail is moved to the south (east) side, then the rail must be closer to the Riviera House, the tall condominium building shown in the photo above on the left side of the trail. Concerns about the potential noise and building vibration caused by the rail will be increased slightly for the many residents in this building. I judge this trade-off between a larger impact on a few homes vs. a smaller impact on a larger number of condominium residents as being a roughly equal trade-off.

We should put some perspective on the potential noise impact of the Purple Line on the Riviera House and the homes near East-West Highway. If you use the Google Maps street view feature of the map above you can see that the homes are very close to East-West highway, closer to the elevation of the highway than to the elevation of the Georgetown Branch trail. If you use the trail, the next time you are on the trail in the area you can stop at the highway bridge underpass and listen. You can observe that the area at the East-West Highway bridge is now a sewer of highway noise at the trail level. I suspect it is worse at the highway level which is closer to the level of the two nearest homes and the condominiums of Riviera House. If you continue down the trail several hundred yards to milepost 2.5, half way to the Country Club, you can still hear the highway noise loudly and clearly even at this distance.

Concerns that modern light rail transit vehicles will disturb the tranquility of homes in this area are grossly misplaced. I believe when MTA performs its background noise measurements as part of the Purple Line noise mitigation design process, the measurements will show the noise from light rail will be insignificant over the existing highway noise in this area, regardless of whether the trail is on the north side or the south side.

Elsewhere along the trail the homes either have very deep back yards (i.e. at the Town of Chevy Chase) or the number of homes with smaller back yards is roughly balanced between the two sides (i.e. at East Bethesda and Edgevale). There is no significant advantage elsewhere along the trail to either a north or south side trail for increasing the separation between rail and the adjacent homes.

3. The need to have a trail cross over: Score one point for the south side trail

Having the trail on the north side along the west end of the corridor, as now planned, will require crossing the tracks to get to the south side someplace before the planned transit maintenance facility at Brookville Road. That cross over is now planned to be on a trail bridge over the tracks at a point about 800 feet west of Jones Mill Road. If the trail is switched to the south side, then this cross over will not be needed. Score a point for the south side trail.

4. How the trail and rail share the East-West Highway underpass: Score one point for the north side trail.

The East-West Highway bridge over the Georgetown Branch corridor has two spans. The eastern span is wider and is used as the underpass by the Interim CCT now – as shown in the photo above. The western span is about half the width of the eastern span. The current plan will put the future CCT under the western span, by itself. The two light rail tracks will pass under the eastern span, separated from the trail by a bridge support column.

If the trail is flipped to the south side, then the trail and one of the transit tracks must share the space under the eastern span and the other track will go under the western span. The trail can be elevated a few feet to give some vertical separation between trail and rail here, but the separation will still not be as good as would be having the trail under the west span by itself and separated from rail by the bridge support column. Score one point for the north side trail.

5. Vertical separation between trail and rail: Score one big point for the north side trail

MTA asserts that the major benefit of having the trail on the north side is that the terrain makes it much easier to keep the trail several feet higher than the rail if the trail is on the north side. This additional vertical separation will make the trail experience more pleasant.

I can only find a few places along the trail where I see the terrain clearly favoring having a higher trail if on the north side. But the one place where this is most evident is also the place where having good vertical separation between the trail and rail will be most important – along the west border of the Town of Chevy Chase.

The Georgetown Branch right-of-way is 66 feet wide along the Town of Chevy Chase. The typical double track and trail Purple Line profile, including a 10′ planted buffer between rail and trail, can generally fit within 66 feet with little difficulty elsewhere. But a stream is close by the south side of the corridor here, and it will be desirable to avoid using all of the 66 foot right-of-way in order to protect the stream. In August, 2008 MTA presented a Technical Memorandum Draft with typical profile revisions and a table showing that for the 1500 feet along the Town of Chevy Chase no space would be allocated for a planted buffer between the trail and rail. The reason was not given, but since this is the only area in the corridor from Bethesda to Stewart Ave. where no space was given to the planted buffer, I can only presume the reason was a desire by MTA to be able to keep the rail further from the stream bed. That means that separation between trail and rail will be reduced here to only a few feet of horizontal separation and a fence and retaining wall. This will still be safe, but having vertical separation as well becomes especially important to maintain an acceptable trail experience.

The terrain slopes very strongly down from north to south toward the stream. In this area MTA is right – having the trail on the north side will greatly facilitate having better vertical separation. If the trail is on the south side, then a much higher retaining wall will be needed to hold the trail higher than rail at this sensitive area next to the stream. Score a point for the north side trail.

Once again we need to step back and keep a realistic perspective in the face of the “Save the Trail” rhetoric. Let’s be honest, the trail is not and will never be in a pristine, quiet, wooded park environment at the border of the Town of Chevy Chase. The photo above shows the trail as it is now – between asphalt parking lots and a concrete drainage ditch on one side, and bamboo on the other side. Good Purple Line design practices can result in a future trail here that is no less safe and attractive than is the existing trail. Having the trail paved and covering over the concrete drainage ditch would be an improvement.

Why is this trail north-south side issue being raised now?

I was at the April 2007 Purple Line Bethesda/Chevy Chase Focus Group meeting at B-CC High School when MTA gave a presentation (pdf) to brief the north side trail idea to the community. MTA showed results of their trade-off study that brought them to the conclusion that the trail should be on the north side, and showed typical profiles comparing the two sides. MTA has presented their plans to build the trail on the north side at public meetings, and specifically to the Bethesda-Chevy Chase Focus Group, numerous times over the 2 1/2 years since then. They presented these plans to the Coalition for the Capital Crescent Trail members and board at the March 2008 CCCT meeting, and the north-south side issue was not among the issues that drew attention from the trail supporters according to the meeting report. Now, after remaining silent on the issue for 2 1/2 years until the Master Plan is being finalized and preliminary design is beginning, a number of Chevy Chase residents are asking for Master Plan changes or more study that could delay the project. They fail to show how more study will show any significant information that has not been available for the last 2 1/2 years. But getting more information is not their real purpose – the purpose is to obstruct and to delay.

Back to the bottom line: If we sum up the scorecard of impacts on the Trail, we see the north side trail wins. But there are winners and losers either way, and people will always be ready to argue from their own perspective. I do not believe trail users and trail support groups can assemble a compelling argument to justify delaying the Master Plan and design process to complete yet another study. If we do ask for a delay to study this issue, we need to answer one question – why didn’t we raise objections when we were being regularly asked since over 2 1/2 years ago?

Several residents from Chevy Chase neighborhoods near the Georgetown Branch Trail spoke against the double track Purple Line in the Functional Plan at the Dec. 10 Planning Board public hearing. They argued that double tracking would greatly increase the impact on the Trail over the single track trolley approved in the first Georgetown Branch Master Plan, and that it was an unfair ‘bait and switch’ to change the master plan to a double track system now when the original plan was for only a single track trolley.

You only have to lift the curtain a little to see how uninformed this argument is.

Single tracking is not as important for a good trail alongside light rail as are several other design practices. The trail with rail shown above has about the same separation distance between trail and rail as would the Purple Line in the Georgetown Branch corridor. The presence of the second track on the right side of the photo can hardly be noticed from the trail compared to the other aspects of the design including the buffer between the trail and transit, the grass tracks, and the transit vehicle.

There are several features of single tracking that would greatly limit any real benefits to trail users:

1 – The Purple Line would be single tracked only for a short section between the transit platforms at Bethesda and at Connecticut Avenue.

The section of the Georgetown Branch corridor proposed for single tracking is only a distance of about 0.9 miles. It cannot be single tracked at or near the transit stations for operational reasons (the vehicles must be able to pass each other at stations). One of the speakers at the public hearing complained that double tracking greatly complicated the problem of bringing both the trail and light rail through the constrained space in the Bethesda Tunnel. But light rail has always been planned as double track in the tunnel. The 1996 Preliminary Engineering Drawings for the Georgetown Branch show the so called “single track” trolley as having double tracks in the tunnel at the station platform, and also east from the tunnel for 580 feet until the tracks merge. All of the issues of how to fit two tracks and a trail through the Bethesda Tunnel must be dealt with, regardless of any decision about single tracking between stations. The Georgetown Branch trolley station at Connecticut Avenue has a similar double track section leading to the platform, as shown in the 1996 Preliminary Engineering Drawings. The double track extends for 1000 feet west from the station platform over Connecticut Avenue to the vicinity of the first County Club putting green and tee, and also 1000 feet east from the platform.

2 – Single tracking will not increase the width of the buffer between trail and rail.

The single tracking is being proposed to save trees in the Georgetown Branch corridor and to keep the transit tracks as far from adjacent properties as possible. These goals require minimizing the width of the total transit and trail profile, and cannot be met if the space “saved” by single tracking is put back into a wider buffer between the trail and the transit tracks. It is extremely unlikely the residents of Chevy Chase who are raising the single track issue will let the ‘benefit’ of single tracking go to increasing the trail buffer instead of to increasing the buffer between their homes and the Purple Line.

The sketch above shows the old proposed Georgetown Branch Trolley at a typical single track section. Note the distance between the center of the tracks and the edge of the trail is 18 feet.

By comparison, the distance between the center of the nearest track and the edge of the trail for the proposed Purple Line typical section above is 20 feet. The distance from the trail to the nearest track is virtually identical for both the older Georgetown Branch trolley single track concept and the Purple Line double track concept. The Purple Line typical profile shows several transit design “best practices” that are not in the older Georgetown Branch Trolley plan – the planted buffer, an elevation difference between transit and trail, and a fence. Not shown but also proposed is grass tracks. These will impact the trail user’s perception of the transit more than will the presence of a second track.

3 – Single tracking would spare (at best) only a few trees.

The second track will add about 12 feet in width to a typical transit and trail profile over what single track transit would have. It is unlikely much of that reduced width will save trees during construction. When MTA studied this issue they concluded in their “Single Track in the Georgetown Branch right-of-way” report:

“While building a trail and single-track transitway would reduce the width required for permanent use by 10-12 feet, construction of that arrangement would still require clearing of most of that 66-foot width. As the trail would be largely at a different elevation than the transitway along the master plan alignment, construction of one track of the transitway would require access from the side. When building one track, the construction equipment would use the space for the other track and vice versa. Therefore, the hoped-for intent that building a segment of trail and single-track segment would reduce the amount of tree clearance from what would be required for building a trail and double-track segment not likely be achieved.”

That 12 foot reduced profile width would be available to replant trees after construction is completed. But the trees now in that zone will not be spared.

The MTA single track study also concluded that coordinating the safe movement of transit vehicles going in both directions on the proposed 0.9 mile long section of single track would create severe operational constraints that would reduce the level of service for the Purple Line. We have already experienced this with the failed effort to operate single track sections in the Baltimore light rail system.

Contrary to the assertions of Purple Line opponents that double tracking is an unfair bait and switch from the original single track trolley plan, double tracking was anticipated in the earliest master plan. Craig Simpson addressed this issue in the Purple Line NOW! testimony to the Planning Board. Purple Line NOW! reminded the Planning Board that the Georgetown Branch Master Plan approved in 1990 not only selected light rail, but also specifically states on page 49:

“In the event future consideration is given to implementing additional double track sections, the existing right-of-way is generally sufficient with appropriate structural treatment to accommodate the necessary typical 56-foot trolley/trail cross section (see Figure 4), except along the Metropolitan Branch section from Talbot Avenue to Silver Spring.”

The language “additional double track sections” appears in the 1990 Master Plan because the trolley was to be double track for as much as 1000 feet on either side of each of the five station platforms for operational reasons. This so called “single track” Georgetown Branch trolley was to be double track for over 1/4 of its 4.4 mile length, at all of the stations where some of the most severe design constraints exist. Assertions that to consider double tracking now for the Purple Line is an unfair ‘bait and switch’ from the previous plan are unfounded and uninformed.

Trail supporters should keep the focus on what is really important, and not get drawn into an off track single-track diversion from transit opponents in Chevy Chase. Eliminating the second track will have very little impact upon trail users but will cripple the Purple Line. Best practices in modern light rail design include grass tracks, landscaped and planted buffers, and using the new, quiet transit vehicles. These can do much more to maintain a pleasant trail environment than can single track.

Many trail users join me in believing that given the Georgetown Branch corridor having been purchased by the county for future transit use, and also given the trail will be rebuilt to a high design standard and will be completed into downtown Silver Spring with the Purple Line, trail users cannot reasonably refuse to share this corridor with light rail. But regardless of whether we support or oppose the Purple Line, we should agree that when we do share the corridor we do not want to severely cripple transit by having a short single track section that gives us very little benefit. I want any accommodation trail users make to be for a fast and efficient transit system.