Metro: "Rosslyn Bypass" (interline) not feasible

[JDC]

Metro's PlanItMetro blog posted a story today saying that after further study, it determined that the Rosslyn bypass/interline connection was not feasible as part of its Metro 2025 plan. http://planitmetro.com/2014/07/03/new-b ... revisited/. Instead, the post notes that the second option, a second Rosslyn station, was deemed feasible.

[asdf]

good. interlining is terrible and should be avoided at all costs

[Sand Box John]

The issue over the feasibility of the connection the C route south Rosslyn to the K route west of Rosslyn is more about money then engineering. There are several locations where WMATA dug tunnels under existing structures. Most of them are tunnels excavated through bedrock which happen to be the type tunneling this would be.

[DiscoveryAnalysis]

Another solution could be to construct a single platform just east of the current station on the level of the TRK 2 platform and utilize this for trains to T/B at from either Huntington or Franconia. Construct a siding to diverge from TRK C1 to become level with TRK C2 at Rosslyn. Construct a pass through passageway on the lower level to allow passengers to transfer directly to Outbound SV/OR trains.

Trains could utilize the C06 interlocking to crossover during the return trip.

This would be a cost effective solution to allow for easier transfer for suburban trips in VA while freeing up space on BL trains traversing the core.

Also knockout panels can be built in to accommodate future growth if funded.

[Sand Box John]

"DiscoveryAnalysis"
Another solution could be to construct a single platform just east of the current station on the level of the TRK 2 platform and utilize this for trains to T/B at from either Huntington or Franconia. Construct a siding to diverge from TRK C1 to become level with TRK C2 at Rosslyn. Construct a pass through passageway on the lower level to allow passengers to transfer directly to Outbound SV/OR trains.

Trains could utilize the C06 interlocking to crossover during the return trip.

This would be a cost effective solution to allow for easier transfer for suburban trips in VA while freeing up space on BL trains traversing the core.

Also knockout panels can be built in to accommodate future growth if funded.

That solution would be rendered useless after the construction of the second Rosslyn station placed west of the existing station to accommodate the proposed future M Street subway.

The second Rosslyn station anyway you slice it will place the platform above the existing upper level platform or below the existing lower level platform to pass over or under the existing K route tunnels. Me thinks it will be below the lower level because there isn't enough bedrock at that shallow of a depth and the grades in the tunnel to get to M Street on the other side of the river would be to great.

[JDC]

The GGW blog has a post today on this issue. Just wanted to pass the link on: http://greatergreaterwashington.org/pos ... -possible/

[realtype]

Something I've never understood is how Rosslyn is a chokepoint and Stadium-Armory is not. I understand that a lot of trains coming from both the Orange and Blue lines travel through Rosslyn creating congestion, but logically just as many trains must converge at Stadium-Armory (or more specifically the Benning Road viaduct). The only difference I can see is that Rosslyn has a much larger number of passengers boarding and alighting.

[Sand Box John]

"realtype"
Something I've never understood is how Rosslyn is a chokepoint and Stadium-Armory is not. I understand that a lot of trains coming from both the Orange and Blue lines travel through Rosslyn creating congestion, but logically just as many trains must converge at Stadium-Armory (or more specifically the Benning Road viaduct). The only difference I can see is that Rosslyn has a much larger number of passengers boarding and alighting.

2 things:

• The Blue, Orange and next weekend the Silver lines generate more boarding on the west side of the railroad then they do on the east.
  The close proximity of C & K junction to the platform in the Rosslyn station prevents trains from moving through the interlocking at speed.

Neither of these conditions exist at D & G junction.

The condition is amplified because of the limited assets WMATA has available to them to run the railroad.

There is another minor detail that differs C & K junction from D & G junction, The K route is, both inbound and outbound, the slower path through the C & K junction turnouts. In D & G junction the slower path inbound is the G route, outbound the slower path is the D route.

[realtype]

"realtype"
Something I've never understood is how Rosslyn is a chokepoint and Stadium-Armory is not. I understand that a lot of trains coming from both the Orange and Blue lines travel through Rosslyn creating congestion, but logically just as many trains must converge at Stadium-Armory (or more specifically the Benning Road viaduct). The only difference I can see is that Rosslyn has a much larger number of passengers boarding and alighting.

2 things:

• The Blue, Orange and next weekend the Silver lines generate more boarding on the west side of the railroad then they do on the east.
  The close proximity of C & K junction to the platform in the Rosslyn station prevents trains from moving through the interlocking at speed.

Neither of these conditions exist at D & G junction.

The condition is amplified because of the limited assets WMATA has available to them to run the railroad.

There is another minor detail that differs C & K junction from D & G junction, The K route is, both inbound and outbound, the slower path through the C & K junction turnouts. In D & G junction the slower path inbound is the G route, outbound the slower path is the D route.

Very interesting. I figured the high ridership in Arlington played a role, but didn't realize that about the junctions. Thanks!

[Sand Box John]

"realtype"
Very interesting. I figured the high ridership in Arlington played a role, but didn't realize that about the junctions. Thanks!

What you may not know is WMATA lowered the civil speed limits on the railroad back in the 1990s to extend the life of the rolling stock, more specifically the 1k cars, and to reduce wear and tear on the track. The speed limit through the slower path of the junction turnouts was as I recall 45 MPH back then, 40 MPH is the speed limit in the platform track circuit. The speed limit through the slower path of the junction turnouts is now under 30 MPH.

The slower speed limit increases that amount of time it take to move trains through the Rosslyn station and junction and vice versa. To make things worse, the reduction in speed has created an imbalance in the how fast train can pass through the junction and service the station because WMATA has, in order the increase capacity on the Orange line and to accommodate the Silver line, has increased the number of trains using the slower path.

WMATA could eliminate the imbalance by increasing speed limit through the junction turnouts to the original civil speed limit without changing the speed limits on the rest of the railroad. WMATA will likely not do that for 2 reasons: They don't want to budget more funds for maintenance on the junction turnouts and the don't want to increase the risk of the possibility of having a derailment in the junction.


One of the things I have noticed over the years is the imbalance of the car series involvement in bad track related derailments. The highest percentages involved were 5k and to a lesser extent 6, 2, 3 and 4k cars. I think the reason why has to do with the design of the trucks. The trucks under the 1k cars are a lighter weight version of a common carrier railroad passenger car truck, the trucks under the rest of the fleet are of designs not derived from a common carrier railroad design.

[JDC]

One of the things I have noticed over the years is the imbalance of the car series involvement in bad track related derailments. The highest percentages involved were 5k and to a lesser extent 6, 2, 3 and 4k cars. I think the reason why has to do with the design of the trucks. The trucks under the 1k cars are a lighter weight version of a common carrier railroad passenger car truck, the trucks under the rest of the fleet are of designs not derived from a common carrier railroad design.

John - do you know what the trucks under the 7000-series are? Are they common carrier railroad passenger car truck, or not?

[Sand Box John]

"JDC"
John - do you know what the trucks under the 7000-series are? Are they common carrier railroad passenger car truck, or not?

I haven't had the chance to see them up close to know, so I don't know if they are derived design or are base on another design. I do know they are inboard frame trucks like the trucks under the rest of the fleet.

The 1k car trucks are a light weight version of the trucks used under the Pioneer III multiple unit commuter cars built by the Budd company. The Pioneer III inboard frame truck is a design that was introduced to reduce the overall weight of passenger car. The trucks were manufactured by Rockwell and are of cast steel.



The biggest difference between the Pioneer-III Rockwell truck pictured above and Rockwell trucks under the 1k cars is the use of the more common nose suspension traction motor setup. Unfortunately I don't have a picture a 1k truck for comparison.

[Robert Paniagua]

After reading this, I sure hope they do Plan B, the second Rosslyn Station or a whole new Bypass route around Downtown DC, which would be better with a separate Rosslyn Station.