Most of the S-train network in Copenhagen is equipped with an
early-seventies cab
signalling system called HKT (for Danish HastighedsKontrol og
Togstop, speed checking and train stop). HKT has continous data
transmission along the line through induction loops between
the rails. Unlike the newer ATC, HKT has more
»virtual blocks« than physical signals. The end of each HKT block
is marked with low fixed stop marks next to the track.
With HKT, the minimal headways on the busiest stretch from Dybbølsbro through Hellerup are down to 2 minutes. The only parts of the network that don't have HKT are Hellerup (excl.) - Holte - Hillerød, and Veksø (excl.) - Frederikssund.
The signals on HKT-equipped stretches are still able to show conventional aspects. This is used when the HKT equipment (off or on the trains) fail, or for signalling to maintenance vehicles, freight, or occational special trains without HKT.
YELLOW\YELLOW |
»Conditional stop« One or more HKT sub-blocks behind the signal are free. Trains without working HKT equipment should stop at the signal. |
WHITE COLON |
»Passing allowed« As a special exception PU signals seen by HKT enabled trains leaving a station will not see Go but Passing allowed. This is because a Go should be able to guarantee to trains without HKT that they can indeed leave the station on conventional signalling. |