"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.
John in the sand box of Maryland's eastern shore.