MCB-OD timing

[robert1297]

I was wondering if anyone could advise on the timing for operation for MCB-OD in the UK. From x21 it states the timing sequence takes 35s from the start of the amber. Later on it goes on to say 35 + 10(what is the 10s for?)this 45 plus 20s for MROT for 2nd train. Is there a strike in point at 65s for 2 lines then with 20s delay timer started then? And at what point does the sequence start after the 20s timer or is it another 10s after this?

Also does the OD scan continuously after its warmed up until it's last scan before the crossing clear is given for the protecting signal to show a proceed

Any advice would be appreciated.

Thanks

[Zaphod]

I was wondering if anyone could advise on the timing for operation for MCB-OD in the UK. From x21 it states the timing sequence takes 35s from the start of the amber. Later on it goes on to say 35 + 10(what is the 10s for?)this 45 plus 20s for MROT for 2nd train. Is there a strike in point at 65s for 2 lines then with 20s delay timer started then? And at what point does the sequence start after the 20s timer or is it another 10s after this?

Also does the OD scan continuously after its warmed up until it's last scan before the crossing clear is given for the protecting signal to show a proceed

Any advice would be appreciated.

Thanks

Hi Robert,

The additional 10 seconds is because the unrestricted aspect (i.e. green) must be displayed to a train for 10 seconds before it reaches the AWS magnet. So the 45 seconds is the point at which the sequence must start, measured from the AWS magnet.

So yes, for a double track line, there is typically a strike-in point at 65 seconds. The crossing will begin operation for a 'first train' as soon as the 20 second timer elapses.