Skipping stops…we know some of you don’t like it, especially the folks who get by-passed, but sometimes – for operational reasons – it has to be done.
We have said many times that our top priorities are getting you to work and home safely and on-time. If delays must happen, we’d rather they be only a few minutes so that the inconvenience to our riders is minimal. Unfortunately, there will be times when our trains become significantly delayed. When these delays happen before a train leaves its first station, a domino effect to all of the following trains often occurs.
This is where the idea of “skipping stops” comes into play. First, a train must be delayed at least 30 minutes. Second, the train behind it must be on-time with no foreseeable potential for delays. This way, the riders at the stations that are skipped only have to wait another five to ten minutes for the following train.
In the morning on the Fredericksburg Line, these stations are usually Leeland Road and Brooke. On the Manassas Line, the Manassas and Manassas Park stations are usually skipped. Evenings are bit more difficult to implement because the following train is not normally on the same line. However, there have been times when this occurs, and depending on the circumstances, the L’Enfant, Crystal City and Alexandria stations have all been skipped over (usually due to extreme crowding).
Because of the complexity, only morning service will be discussed here.
The two underlying reasons for skip stops are to maintain the total trip length and to ease crowding concerns.
Total Trip Time: Under normal operations, most VRE trains have a station dwell time of about 2 minutes or less. Second, trains are normally spaced about 20-30 minutes apart on each line.
Skip Stopping When Delays Exceed 30 Minutes: Railroad signal systems are designed to separate trains. The system determines where a train is and provides the signal indication to the blocks behind the train. Only one train can occupy one “block” at a time, usually an average distance of 2 miles (keep in mind that the system has to keep freight trains in mind which can be at least one mile long). Trains in the 2 to 3 blocks behind a train receive signal indications that force them to slow down below the maximum authorized speed for that area.
By skipping stations, we can open up that space between the two trains. If spaced too close together, a train that normally operates at 70 mph must operate at 30 to 45 mph, when following a delayed train.
By skipping stations at the beginning of the line, we can usually save about 10-15 minutes on the first delayed train, but the second train’s savings are much more significant. By operating at a faster speed, we are likely to reduce the delay to the second train by about 30 minutes.
When Skip Stopping Is Not Employed: There are times when skip stopping is not feasible.
In order for skip stopping to be effective, the following VRE train must be close behind the first VRE train. If the problem is one that affects all trains, like a switch problem, then skipping stops is not used. Also if an Amtrak or freight train is operating between the two VRE trains, then skip stopping would not be employed.
Crowding: Most VRE trains are assigned train sets that roughly match their ridership. On both lines, the heaviest passenger loads are at the first three stations.
Without Skip Stopping: With the ridership demand for the delayed train at each station equaling two train loads of riders, dwell time increases. It not only increases because of the numbers of people trying to get on, but it also becomes harder for those who are trying to get off amidst the crush load of riders, causing further delays. This is especially true on the Fredericksburg Line for riders detraining in the morning at Quantico, Woodbridge, Lorton and Franconia/Springfield.
Using the Fredericksburg Line, if a train is over 30 minutes late, it can have a demand of up to 956 riders at Fredericksburg, Leeland, and Brooke (two train loads of passengers).
However, the train has a capacity of 798. A rider at Brooke may not be able to board the train because the capacity could be exceeded. Riders further up the line, who are equally delayed, would be even less likely to be able to board. In addition, the following train will likely pick up only about 15 riders at Fredericksburg, Leeland, and Brooke, and will be mostly empty.
Using the previous example, with skip stopping the train loads roughly 485 riders at Fredericksburg. The train then can handle the 367 riders at Quantico, Rippon, Woodbridge, and Lorton, for a total of 852 riders. Although over capacity, it can handle the load with standees. The following train picks up 471 riders at Leeland and Brooke and makes all following stops. The train is more likely to remain on schedule and has no crowding.
So what is the bottom line? With skip stopping, the delays to both trains are minimized. Without skip stopping, a delayed train’s dwell times doubles as the train becomes overloaded. Skipping stops becomes especially important if significant delays occur at the beginning of the morning. Experience has shown that when the first delayed VRE train does not skip stops, it can create a domino effect delaying all rush hour VRE trains. When we skip a few stations, we are normally able to limit the delays to only two VRE trains.