Updated 980611
The 1961 rule change saw the implementation of full speed signaling on Entry Signals. Until then, even thought an Entry Signal did show the permitted speed, this speed was not advance signaled. Track useage on stations was timetabled and trains had to be stopped and notified in case of changes. This practice became unacceptable with the introduction of CTC in the late '50s. With the 1961 change it became possible to let trains run "by the signals".
The early '60s saw the construction of the new route between Copenhagen and Hamburg, via the new ferry link between Rødby Færge and Puttgarten. This meant an upgrade of the existing single track line from Vordingborg to Nykøbing Falster plus the construction of a new single track line from Nykøbing Falster to Rødby Færge. The upgrade meant installation of relay interlockings and CTC plus rebuilding the existing stations.
A new type of single track station was introduced. As a completely new feature this new station type allowed trains to enter the station from both sides simultaneously. Where traditional single track stations only allow entry routes with a safety overlap stretching to the switch limits, this new type of station had a long siding that would allow a (short) safety overlap to be contained inside the switches. Trains could thus be allowed to enter the station at reduced speeds from both sides simultaneously.
Coming from a practice of only running according to timetable, to running entirely by the signals, meant a severe change of mindset. Therefore these stations were constructed to give a more restrictive signaling than were strictly necessary by the book, as will be explained below. These extra precautions are not considered necessary today. The repeater Platform Exit Signals are mandatory for this type of station, as they are used to reinforce the cautious signaling in case of simultaneous entry.
When an entry route is set but no "close" meet is likely, normal entry routes with overlap stretching to the switch limit and normal entry signaling is used.
When an entry route to the trough track is set, trains are permitted to enter the station at line speed. The entry route ends at the outermost Platform Exit Signal. Since the safety overlap stretches all the way to the switch limit, the end point Platform Exit Signal shows "No Passing" in line with practice at the time. The repeater Platform Exit Signal shows "Pass", also in line with standard practice.
An Entry Route to the siding is similar to an entry route to the through track, except that entry speed is limited to 60 km/h (40 mph) by the entry switch.
Through signaling on this type of station is also quite ordinary. Through through track is permitted at line speed and is marked by the Entry Signal showing "Proceed Through (station)".
Through siding is signaled as an entry route to the siding, combined with an exit route from the siding.
If the CTC announces the trains in a meet to show up more or less simultaneously, the interlocking system goes into Simultaneous Entry mode. In this mode antry routes will only have a safety overlap extending the length of the siding. This allows an entry route to the other track to be set at the same time. The two entry routes are set as their trains approach, but the Entry Signal is held at "Stop" initially. The end point Platform Exit Signals show "Stop" as the entry routes do not have a safety overlap extending to the switch limit. To reinforce the restrictive signaling, the inner Platform Exit Signal shows "Pass with Caution". This is the reason for the inner Platform Exit Signals , as these signals are mandatory for this type of station.
The interlocking awaits the trains to pass the Distant Signal. 15 seconds later the Entry Signal is released to show "Proceed at Reduced Speed", 40 km/h (25 mph). The 15 seconds delay is built in to enforce the reduced speed, by ensuring that the train is slowed considerably before the Entry Signal clears.
As soon as a train is in the clear, the interlocking sets the exit route of the opposing train. The restrictive signaling on the Entry Signal is not released....
...until 2 minutes after the first train occupied its platform track, at which time it is assumed that the train has stopped.
The end point Platform Exit Signal will stay at "Stop" until the switch is lined as it would have been, had the safety overlap extended all the way to the switch limit.
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