Height Restrictions - Warning vs Prohibited

[jabbaboy]

Just something that I'm curious about but what's exactly the difference between these signs. The North East can't seem to decide which one to use so there's both variants used depending on the bridge but there's nothing that stands out that's different between the bridges.

[DanT97]

May I assume that you’re referring to the possibility of using triangular or circular signs in this scenario? Is so, from what I understand, circular signs indicate prohibition, so are likely to be used in the case where there is great danger from a bridge strike. Triangular signs, on the other hands, are for warning motorists about hazards. These wouldn’t be mandatory, so might be used where there is a bit of wiggle room with bridge heights. For example, this would be expected at an arched bridge, where a slightly taller vehicle could just about squeeze under if it passed under the highest part of the bridge in the centre. The clearance given on of these signs would typically refer to a vehicle remaining in its own lane. I hope this information helps you, if you have any questions, don’t hesitate to ask away.

[Paul7755]

Just something that I'm curious about but what's exactly the difference between these signs. The North East can't seem to decide which one to use so there's both variants used depending on the bridge but there's nothing that stands out that's different between the bridges.

An expert answer will no doubt appear later, but I think the gist of the signage requirements is to put a Warning sign on an arched bridge, and a Prohibited sign on a flat girder bridge. The former usually has a width marked, and a higher but narrower vehicle would still be able to pass through.

[Nathan_A_RF]

Under the current regulations, prohibitory (circular) height restriction signs are for beam bridges, whereas warning (triangular) height restriction signs are for arch bridges and overhanging buildings/structures. Any other combo is incorrect. See the Traffic Signs Manual Chapter 4 Section 7 for more info.

[jabbaboy]

Thank you for the quick answer, I had a feeling that might be the case.

The reason I was asking is there's lots of examples, but just to pick one, here where there's triangle signs used on non arch bridges and definitely bridges where they're at risk at being at strike.

Not to mention stuff like this here which I assume is a botch in itself since there's absolutely nowhere for anyone over that height to go beyond that sign.

[Nathan_A_RF]

Both those cases are incorrect yes. The first should be a prohibitory sign as should the second pair.

It is therefore particularly important that the signs and markings on low bridges are correctly installed and maintained to a high standard.

If only that was the case...

[DanT97]

Did anyone read my post here?

[Big L]

Did anyone read my post here?

Yes. You explained the difference between triangular and circular signs then guessed why each would be used. People that actually know why then came along.

[traffic-light-man]

I think this has come up before but I can't remember the answer - is there something specifically stopping an authority from applying a TRO based on height to any length of road, with reason?

I.e., if you had an arched bridge with regular strikes, could you sign the bridge itself with the usual warning signs, but then TRO the road either side of the bridge (perhaps from the last 'escape' route) with an enforceable height restriction?

[Nathan_A_RF]

In the TSM it mentions that environmental height restrictions need approval

[Berk]

Just something that I'm curious about but what's exactly the difference between these signs. The North East can't seem to decide which one to use so there's both variants used depending on the bridge but there's nothing that stands out that's different between the bridges.

An expert answer will no doubt appear later, but I think the gist of the signage requirements is to put a Warning sign on an arched bridge, and a Prohibited sign on a flat girder bridge. The former usually has a width marked, and a higher but narrower vehicle would still be able to pass through.

Only if they remember to drive carefully in the middle of the road. Some bridge bashes have been caused by keeping left…

[DanT97]

Did anyone read my post here?

Yes. You explained the difference between triangular and circular signs then guessed why each would be used. People that actually know why then came along.

I’m annoyed at people who related what I already said. Especially, as they seemed to attract more attention than me. Please don’t copy my posts. That is all.

[rhyds]

Both those cases are incorrect yes. The first should be a prohibitory sign as should the second pair.

It is therefore particularly important that the signs and markings on low bridges are correctly installed and maintained to a high standard.

If only that was the case...

I posed on the bridge strike thread a while back about a bridge near me that had both circlular and triangular signs for its height, but the height wasn't consistently signed on either

viewtopic.php?p=1238559#p1238559

There's a few suggestions that the difference between circular signs and triangle signs is that the triangle/warning signs warn you of the available headroom under the bridge while the circular prohibition signs indicate which vehicles are legally prohibited from going under the bridge.

viewtopic.php?p=1238578#p1238578

[rhyds]

Did anyone read my post here?

Yes. You explained the difference between triangular and circular signs then guessed why each would be used. People that actually know why then came along.

I’m annoyed at people who related what I already said. Especially, as they seemed to attract more attention than me. Please don’t copy my posts. That is all.

This has happened since time immemorial on all discussion platforms. I'd really not worry about it...

[Paul7755]

Just something that I'm curious about but what's exactly the difference between these signs. The North East can't seem to decide which one to use so there's both variants used depending on the bridge but there's nothing that stands out that's different between the bridges.

An expert answer will no doubt appear later, but I think the gist of the signage requirements is to put a Warning sign on an arched bridge, and a Prohibited sign on a flat girder bridge. The former usually has a width marked, and a higher but narrower vehicle would still be able to pass through.

Only if they remember to drive carefully in the middle of the road. Some bridge bashes have been caused by keeping left…

Yes I’m sure that happens too, and I expect it will happen despite the pretty obvious markings on the road surface.

[M42_J10]

I thought the old standard was to have triangular height warning signs, but this was changed to having circular prohibition signs (when appropriate for the type of bridge) as this allows a bridge-striking driver to be prosecuted for ignoring the prohibition.

[MotorwayGuy]

This ADS on the South Circular was changed to a triangle and then back to a circular one. The height has also gone from 4.5m to 4.3m and then to 4.4m.

[Bryn666]

https://showmeasign.online/2019/12/20/h ... -approach/

I wrote about this in detail a while ago. Quite honestly the system is a total mess and it's no wonder we have an average of 5 bridge strikes a day.

[Berk]

https://showmeasign.online/2019/12/20/h ... -approach/

I wrote about this in detail a while ago. Quite honestly the system is a total mess and it's no wonder we have an average of 5 bridge strikes a day.

ISTR you also suggested more intensive forward height, and diversion signing in another post?? Which is not radical, but should encourage drivers to react in a more considered way.

[Bryn666]

https://showmeasign.online/2019/12/20/h ... -approach/

I wrote about this in detail a while ago. Quite honestly the system is a total mess and it's no wonder we have an average of 5 bridge strikes a day.

ISTR you also suggested more intensive forward height, and diversion signing in another post?? Which is not radical, but should encourage drivers to react in a more considered way.

Yes. Network management strategies should be doing this anyway especially now we have sat nav drones.