Encouraging head on collision?

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ColinB
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Encouraging head on collision?

Post by ColinB »

I noticed this east of New Alresford where the B3047 passes under the Watercress Line. I assume they don't want traffic to drive on the opposite side of the road. But what are the parallel short dashed lines meant to indicate?

https://www.google.co.uk/maps/@51.08834 ... 384!8i8192
DB617
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Re: Encouraging head on collision?

Post by DB617 »

ColinB wrote: Thu Sep 23, 2021 14:21 I noticed this east of New Alresford where the B3047 passes under the Watercress Line. I assume they don't want traffic to drive on the opposite side of the road. But what are the parallel short dashed lines meant to indicate?

https://www.google.co.uk/maps/@51.08834 ... 384!8i8192
I believe that's the path within which the specified height limit is correct. Vehicles close to that limit should follow the lines, and the bridge should probably be preceded by <!> Oncoming vehicles in middle of road. And as a Luton driver I should probably know that...
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JammyDodge
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Re: Encouraging head on collision?

Post by JammyDodge »

DB617 wrote: Thu Sep 23, 2021 14:25 Vehicles close to that limit should follow the lines, and the bridge should probably be preceded by <!> Oncoming vehicles in middle of road.
They are a little further up the road from the bridge on either side
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Re: Encouraging head on collision?

Post by JohnnyMo »

The bridge/road looks straight so why is the indicated path on a diagonal rather than in the middle
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Chris5156
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Re: Encouraging head on collision?

Post by Chris5156 »

JohnnyMo wrote: Thu Sep 23, 2021 16:00 The bridge/road looks straight so why is the indicated path on a diagonal rather than in the middle
It’s not as straight as it looks. If you compare the bridge wall on the left to the kerb line there is a slight skew.
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Re: Encouraging head on collision?

Post by JohnnyMo »

Chris5156 wrote: Thu Sep 23, 2021 16:02
JohnnyMo wrote: Thu Sep 23, 2021 16:00 The bridge/road looks straight so why is the indicated path on a diagonal rather than in the middle
It’s not as straight as it looks. If you compare the bridge wall on the left to the kerb line there is a slight skew.
Yes just noticed that and was about to delete my post
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Bryn666
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Re: Encouraging head on collision?

Post by Bryn666 »

I hope those guidance marks are not finished as there's no kicker arrow with HIGH VEHS, no lead out tapers... there's a diagram in TSM Ch 4 and 5 for this.
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Re: Encouraging head on collision?

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Bryn666 wrote: Thu Sep 23, 2021 16:34 I hope those guidance marks are not finished as there's no kicker arrow with HIGH VEHS, no lead out tapers... there's a diagram in TSM Ch 4 and 5 for this.
I thought so too - here's how to do it better

https://www.google.com/maps/@51.0885794 ... 312!8i6656

(I originally wrote "How to do it properly" but changed it as someone is bound to come along with a comment :) ).
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Bryn666
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Re: Encouraging head on collision?

Post by Bryn666 »

WHBM wrote: Thu Sep 23, 2021 17:13
Bryn666 wrote: Thu Sep 23, 2021 16:34 I hope those guidance marks are not finished as there's no kicker arrow with HIGH VEHS, no lead out tapers... there's a diagram in TSM Ch 4 and 5 for this.
I thought so too - here's how to do it better

https://www.google.com/maps/@51.0885794 ... 312!8i6656

(I originally wrote "How to do it properly" but changed it as someone is bound to come along with a comment :) ).
That's actually pretty spot on as far as these things go. The real problem is making sure the path for high vehicles corresponds with the arch. You see some examples and just clench your teeth.
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Re: Encouraging head on collision?

Post by fras »

Basically the bridge and the road are skewiff. Not unusual with railway bridges built when the road traffic was horse-drawn.
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Re: Encouraging head on collision?

Post by avtur »

JammyDodge wrote: Thu Sep 23, 2021 15:20
DB617 wrote: Thu Sep 23, 2021 14:25 Vehicles close to that limit should follow the lines, and the bridge should probably be preceded by <!> Oncoming vehicles in middle of road.
They are a little further up the road from the bridge on either side
Hopefully drivers approaching will take note ...
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Bfivethousand
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Re: Encouraging head on collision?

Post by Bfivethousand »

Chris5156 wrote: Thu Sep 23, 2021 16:02
JohnnyMo wrote: Thu Sep 23, 2021 16:00 The bridge/road looks straight so why is the indicated path on a diagonal rather than in the middle
It’s not as straight as it looks. If you compare the bridge wall on the left to the kerb line there is a slight skew.
I assume once upon a time this was the A31 at which time it was far more critical to sign as high a headroom as it was possible to get away with.

It's now far more appropriate to sign a lower headroom with conventional guidelines parallel with the kerblines. There's a very convenient alternative route avoiding this bridge, therefore no reason not to knock three or four feet off the headroom if needs be.
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SteelCamel
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Re: Encouraging head on collision?

Post by SteelCamel »

Bfivethousand wrote: Thu Sep 23, 2021 21:46 I assume once upon a time this was the A31 at which time it was far more critical to sign as high a headroom as it was possible to get away with.

It's now far more appropriate to sign a lower headroom with conventional guidelines parallel with the kerblines. There's a very convenient alternative route avoiding this bridge, therefore no reason not to knock three or four feet off the headroom if needs be.
I don't see a "very convenient alternative route" - there's an arch bridge over the other end of the B3047 too (even though there's no railway on it), and none of the other roads have a connection to the A31. The B3046 also has an arch bridge. Sun Lane actually goes over the railway, and you can get to it from the A31 down Whitehill Lane, but that's very narrow and doesn't really look suitable for HGVs.
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Re: Encouraging head on collision?

Post by Bfivethousand »

SteelCamel wrote: Thu Sep 23, 2021 22:28
Bfivethousand wrote: Thu Sep 23, 2021 21:46 I assume once upon a time this was the A31 at which time it was far more critical to sign as high a headroom as it was possible to get away with.

It's now far more appropriate to sign a lower headroom with conventional guidelines parallel with the kerblines. There's a very convenient alternative route avoiding this bridge, therefore no reason not to knock three or four feet off the headroom if needs be.
I don't see a "very convenient alternative route" - there's an arch bridge over the other end of the B3047 too (even though there's no railway on it), and none of the other roads have a connection to the A31. The B3046 also has an arch bridge. Sun Lane actually goes over the railway, and you can get to it from the A31 down Whitehill Lane, but that's very narrow and doesn't really look suitable for HGVs.
The bridge over the B3047 to the west of the town centre has no signed headroom restriction coming in from the A31 although in the other direction it's signed (poorly) with a clearance of 4.8m (metric only :thumbsdown: ) reflecting the elevation of the arch over the nearside kerb in that direction. No guidance markings either. Bar that, it appears clear that anything below 5.03m / 16ft 6in can get under that bridge albeit with a little care westbound.
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DB617
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Re: Encouraging head on collision?

Post by DB617 »

avtur wrote: Thu Sep 23, 2021 21:37
JammyDodge wrote: Thu Sep 23, 2021 15:20
DB617 wrote: Thu Sep 23, 2021 14:25 Vehicles close to that limit should follow the lines, and the bridge should probably be preceded by <!> Oncoming vehicles in middle of road.
They are a little further up the road from the bridge on either side
Hopefully drivers approaching will take note ...
Something I pray every time I move into the middle, especially with the many weird bridge/road interfaces where they are preceded by blind bends.
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