Automatic block signaling devices of type E in our collection

SBL typu E

Courtesy of PKP Polskie Linie Kolejowe we managed to extend our collection with automatic block signaling (ABS) devices of type E. It was the first common type of automatic block at Polish railway network (except the earlier, two-aspect ABS utilised exclusively by Electric Commuter Railway), designed by Swedish company L. M. Ericsson and manufactured domestically by ZWUS in Katowice.

Former semi-automatic block signaling had limited capacity. Only after the introduction of the automatic block and division of the route into braking-distance long sections it become possible to shorten the gap between following trains and increase the line’s capacity. Therefore ABS was first deployed on main, busy lines.

Block signaling of type E has the following features:

  • it is single-direction – the full capacity can be achieved only when driving in the principle direction (i.e. on the right track),
  • it is three-aspect – except the red and green aspect, block signals can display orange aspect, depending on the number of free blocks in front of the oncoming train.

A curiosity of this type of ABS is the way of sending of the control current between two neighbouring signals. The control signal was send as a phase of track current decoded by a three-state relay of type JRY.

Currently, automatic block of type E is becoming obsolete and is slowly replaced with a bidirectional, four-aspect ABS.

Back to top