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plutopius t1_itvet4u wrote

Reply to comment by 22304_selling in Metro studying Silver Line Express service by walkallover1991

The issue is that when there is a problem with one train/station, the whole rail line has to stop because there's no way for functional trains to pass.

The rest of the world has nothing to do with this. I'm sure there are other train systems that have a similar problem.

The new line I am referencing is the Silver line past the Blue and Orange stops, not a right of way.

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Cythrosi t1_itvq455 wrote

What the rest of the world does is highly relevant, because running a railroad doesn't magically change physics and logistics because a border was crossed.

Most other systems make effective use of signaling and crossovers to maximize a two track configuration to allow quick bypass of problems. They also work to provide effective line density and connections to allow people to simply pick another path to their destination. Running quad track/express systems really only becomes beneficial when you have heavy density and ridership (we have neither of those currently). The money spent on quad track/express service can often be spent providing more service in a parallel corridor which both serves more people/neighborhoods and allows relief off lines when there may be a major issue on another line.

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plutopius t1_itvwb78 wrote

With our "all roads lines downtown" system, adding parallel lines would just cause bottleneck once they converge in the city. What you're saying with parallel lines is relevant for a grid system, which we do not have.

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Cythrosi t1_itw80uo wrote

Not really. Look at London. Its primary focus of most its lines are to pass through the core of London. It is aided though by a massive amount of connections and interchanges that allow immense flexibility. Between the multiple lines with connections at key points, the Overground, the Elizabeth Line, DLR and a robust bus network, a problem on one line doesn't criple the network.

Adding a 4th trunk line (and more in the future even) through DC with more connections and transfer opportunities would do more to improve Metro service than express tracks ever could. Express service only really makes sense when you have the density for it. DC is not dense enough (and probably never will be) to justify the cost of adding express tracks and services on the Metro lines.

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plutopius t1_itwc41k wrote

>DC is not dense enough (and probably never will be) to justify the cost of adding express tracks and services on the Metro lines.

Overall I agree with this. There no need for express in the city. But an express to the airport could've been done with better planning. After-the fact is useless.

Also, much of London Underground uses 4-tracks, which kinda derails (pun intended) what you're saying.

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