by SURGEAHOLIC
butthesingnals were 4 blocks apart what woud happen? cornfield meet?
Railroad Forums
if 2 trains past green absolute signals at same time
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by clearblock
This situation is not possible in a CTC system, as Dutch said, since the DS could not clear opposing moves.
It could occur with 2 direction operation on an APB system and it would result in both trains getting a red at their next signal with the system designed with sufficient braking distance between signals that each train could stop safely. This exact situation is described in detail in the GRS Elements of Railway Signaling book pages 302-305, "Train operation on single track".
The proper solution for an APB system to prevent this problem involves providing 2 approach blocks for opposing moves vs the normal single approach block for a following move. The GRS book discusses the various scenarios and presents a system diagram of how to add a directional stick circuit with double approach protection for opposing moves to a conventional APB system.
Since this is a known issue with a solution, I doubt it should ever be encountered in a properly designed signaling system.
It could occur with 2 direction operation on an APB system and it would result in both trains getting a red at their next signal with the system designed with sufficient braking distance between signals that each train could stop safely. This exact situation is described in detail in the GRS Elements of Railway Signaling book pages 302-305, "Train operation on single track".
The proper solution for an APB system to prevent this problem involves providing 2 approach blocks for opposing moves vs the normal single approach block for a following move. The GRS book discusses the various scenarios and presents a system diagram of how to add a directional stick circuit with double approach protection for opposing moves to a conventional APB system.
Since this is a known issue with a solution, I doubt it should ever be encountered in a properly designed signaling system.
by CN_Hogger
SURGEAHOLIC wrote:butthesingnals were 4 blocks apart what woud happen? cornfield meet?Why would you even ask this question???
by SURGEAHOLIC
CN_Hogger wrote:because ididnt know if it was possibwe or nt. i read up a loton signalling and i knew that one train entering makes the other signals go red but i didnt knw if there was a safety measure f say bth trains entered at exact same time. i always thought the trains woud see theintermediate signals, stop and proceed, then hae to back up once they saw another train, but coud stop in tie due to restricted speed.SURGEAHOLIC wrote:butthesingnals were 4 blocks apart what woud happen? cornfield meet?Why would you even ask this question???