Reduced overlap

[gsibanda]

Hi,

 Thank you for the detailed explanation.

Is there a case where a reduced overlap is considered. I tried to search that, but could not find one.

Can you help me with that, please, if you have one..

Thanks & Regards,

Yes, there are situations where a reduced overlap is considered to be appropriate and sufficient. This is where the approach speed to a signal having the reduced overlap is low and the provision of a full overlap would lead to unnecessary (usually) operational complexity.

On the UK main lines, for an example, if the permissible or attainable approach speed to a signal is 40 miles per hour, the overlap can be reduced to 80 metres as opposed to the standard 180 metres. For an approach/attainable speed of 60 miles per hour, the overlap can be reduced to 135 metres and for any approach speed greater than 60 miles per hour, a minimum of a standard overlap is required.

Sometimes reduced overlaps are also applied where train speeds are very low and the required throughput is high (e.g. on approach to major terminal stations where a high volume of trains terminate and turn around). Using standard overlaps in such cases would unnecessarily increase headways.