Measuring Metro's Performance: A Tight Squeeze Through The Rosslyn Bottleneck

Measuring Metro's Performance: A Tight Squeeze Through The Rosslyn Bottleneck

Friday, August 15, 2014 - 11:43 AM
By Martin DiCaro : WAMU




Metro’s answer to Blue Line riders who have asked the transit authority to restore rush hour trains cut to make way for the Silver Line is: there is simply no more room.

The Rosslyn tunnel, the rail system’s worst chokepoint, can handle no more than 26 trains per rush hour. Now that Orange, Silver, and Blue are sharing the tracks, only five of those trains may be Blue Line. That's down from the seven per hour before the Silver Line opened.

But Metro often fails to reach its scheduled goal of 26 trains through Rosslyn, both in morning (inbound to D.C.) and afternoon (outbound to Va.) rush hours.

There are several reasons for less than optimal performance.

* Train or track problems: On August 6, a disabled train on the Orange Line forced single-tracking, sending delays rippling across the system. Only 14 outbound trains made it through Rosslyn between 6 and 7 p.m. that Wednesday, and only two were Blue Line.

* Crowding: It’s a vicious cycle: crowded trains take longer to unload and load once they arrive at the platform. This slows down the Blue/Orange/Silver parade, causing trains further down the line to become even more crowded.

* Manual operations: Because Metro’s trains have yet to return to Automatic Train Operation, individual operators are in control of acceleration and deceleration. Each operator drives a train differently, and some are more efficient than others at pulling into and then accelerating out of a station. Over the course of an hour, a few lost seconds per train adds up to an extra minute or two of delays.

According to data provided by Metro and compiled by MetroMinder DC, an app that measures the rail system's performance, in the first week of Silver Line service (July 28 through August 1), an average 25 outbound trains passed through the bottleneck between 5 to 6 p.m. Between 6 and 7 p.m., the average fell to 23.7 trains/hour. ...................(more)

The complete piece is at: http://www.wnyc.org/story/measuring-metros-performance-tight-squeeze-through-rosslyn-bottleneck/