Translations:How to operate relay line block equipment/27/en

Changing directions

(Some pictures made by @Skully) The direction change is set up to prevent two trains from entering an automatic block line from both sides at the same time. On single-track lines with SBL, such a change of direction is mandatory. Most double-track SBL lines are also equipped with a change of direction, only a few SBL lines on double-track railways do not have a change of direction installed. On double-track SBL lines, a change of direction allows trains to run in the opposite track under full technical protection. Here, SBL signals are also set up at the same intervals as in the regular track. Train movements in the opposite track are controlled as usual under the clear aspects of main signals. When entering the opposite track, the signal W24 is indicated at the interlocking-controlled main signal. Driving on the left track can be used to accelerate the operational flow (e.g. overtaking on the run). In addition, the permanently installed change of direction simplifies operations during construction work, track closures, broken down trains, disruptions, etc. that only affect one track. The change of direction is possible when the arrival permission indicator is lit in white. To do this, the Zwbl button must be pulled. The line block now checks whether:

• all block sections between the signal boxes are free
• an exit into the automatic block line has been set.
  

If all block sections are free and no exit to the line has been set, the arrival permission indicator starts flashing. Now all automatic block signals are switched dark with the exception of the signals with W18 board. When this is done, the arrival permission indicator goes off and the block section indicators flash white. The line block has now entered the neutral state.

The new direction of travel can be requested with the Wbl button. The block section indicators continue to flash white, in addition the departure permission indicator now flashes. The neighbouring signal box must now cooperate and agree to the change of direction. As soon as this has happened, the departure permission indicator and all block section indicators light up in steady white light. The direction of run has now been changed and a train can be released. If a train is now to be let into the opposite track, the corresponding "NO" button for the left track must be operated. As long as the "NO" operation is active, the indicator next to the button lights up white. If a replace signal (Sz) on the station side is operated while the "NO" indicator is lit, the opposite track indicator W24 is also switched on.