Automatic Barriers v Control Room Operated

[shakey1961]

Hi.

For those of you familiar with Merseyrail, on the whole Northern Line to Southport there is just one automatic barrier at Crescent Road.

My question is this... Why if it's ok to have an automatic barrier come down much later and stay down less than the other crossings, why can't all the crossings be timed the same way?

There are some barriers on that track that stay down for a very very long time.

I know it'll probably come down to safety, but if the automatic one can do it, why can't certain other crossings do it?

Thanks for your replies.

 

[Rich McLean]

Hi.

For those of you familiar with Merseyrail, on the whole Northern Line to Southport there is just one automatic barrier at Crescent Road.

My question is this... Why if it's ok to have an automatic barrier come down much later and stay down less than the other crossings, why can't all the crossings be timed the same way?

There are some barriers on that track that stay down for a very very long time.

I know it'll probably come down to safety, but if the automatic one can do it, why can't certain other crossings do it?

Thanks for your replies.

Automatic Half Barrier crossings are not protected by restrictive signals. These barriers are operated via a track circuit. Due to the fact signals should be OFF if line ahead clear, there is no need to have a lengthy waiting time. These are also half barriers to give vehicles already on the crossing a means of escape

CCTV and box managed barriers however are protected signals. In order not to slow down the incoming service, the barriers needs to be down and crossing clear, in turn signal set to OFF before the approaching train reaches the protecting signals . In some case this could be 2 or 3 blocks away (3 & 4 aspect areas), so barriers will be down for longer unless the train is checked down (which happens from time to time when idiot drivers/pedestrians don't clear the crossing fast enough)

Hope that helps

 

[shakey1961]

Yes that helps. Though I don't know the ins and outs of railway terminology I am understanding.

Just a terrible wait when you have a train passing a crossing and you just know the train going to pass in the opposite direction hasn't even arrived at the stop, but you know it's probably entered the area to keep those barriers down.

Sometimes, it doesn't make sense to me, but I know it's all done for a reason.

Thanks for your reply.

 

[Bald Rick]

On a like for like basis, an automatic half barrier crossing has a safety risk several times greater than a supervised crossing (MCB, MCB CCTV, MCB OD).

 

[cool110]

The problem with the Southport branch of the Northern Line is that nearly all of the crossings are next to stations. So automatic barriers are not possible due to not knowing how long it'll take for the train to get over the crossing after passing the activation point and it can't be at the end of the platform because that doesn't leave time at for the barriers to come down.