What's the speed limit at this junction?

[Chris5156]

We've talked before about dual carriageways where there's a different speed limit in each direction - places like the M4 near Heston Services, which is 60 eastbound and 70 westbound.

What happens where a dual carriageway with a different speed limit in each direction has a gap in the central reservation?

I've found a place where it happens, here on the A31 Farnham Bypass.

If you're travelling westbound, the limit is 50 - you can see the last repeater before the junction here, and there's other 50 repeaters after it too.

If you're travelling eastbound, the limit is 40. Again, the last repeater before the junction is here, and there are more after it (though the limit then goes up to 50 not long afterwards).

If you're joining or crossing the A31 from the side roads at either side of the crossroads, the 30 limit on either side gives way to a higher limit on the main road. Approaching from the north, signs will tell you you're entering a 40 limit, but that's only true if you're going to turn left. People turning right are joining a 50 limit. And of course everyone crossing the central reservation is passing from a 40 limit to a 50 limit without any boundary sign.

If you're approaching from the south, no attempt is made to signpost the speed limit at all - the reverse of the 30 terminal signs is simply blank. What's actually happening is you're entering a 50 limit, but if you go straight on you immediately cross into a 40 limit, again with no signs.

I've got a feeling this junction renders both the 40 and 50 limits unenforceable, because there's a boundary between them that has no signage, and joining traffic here is given no appropriate indication of what's happening. Is it unique?

[Bryn666]

The easiest, and most compliant solution, would be to swap the signs around so the A31 crosses a 30 limit, as you would do with a roundabout where the lower speed limit is supposed to apply to the junction. Then you'd have your 40 and 50 terminals on the A31 and job done, although it'd look a bit silly having a 30 and 40/50 in the same line of sight.

The expensive answer is to reduce the approach to the junction to 40 so both carriageways have the same speed limit through the junction.

[Chris5156]

The easiest, and most compliant solution, would be to swap the signs around so the A31 crosses a 30 limit, as you would do with a roundabout where the lower speed limit is supposed to apply to the junction. Then you'd have your 40 and 50 terminals on the A31 and job done, although it'd look a bit silly having a 30 and 40/50 in the same line of sight.

I think the only other way round would be to bring the start of the eastbound 50 limit forward to the point where the eastbound carriageway widens to two lanes - it's really only 40 because of the merge to a single lane under the bridge. But that has the unfortunate side effect of raising the limit just before the traffic lights.

It is, in every sense, a mess!

[Bryn666]

The easiest, and most compliant solution, would be to swap the signs around so the A31 crosses a 30 limit, as you would do with a roundabout where the lower speed limit is supposed to apply to the junction. Then you'd have your 40 and 50 terminals on the A31 and job done, although it'd look a bit silly having a 30 and 40/50 in the same line of sight.

I think the only other way round would be to bring the start of the eastbound 50 limit forward to the point where the eastbound carriageway widens to two lanes - it's really only 40 because of the merge to a single lane under the bridge. But that has the unfortunate side effect of raising the limit just before the traffic lights.

It is, in every sense, a mess!

I had no idea the A31 did that there, is that a 1950s bridge that was deemed not worth replacing? It reminds me of the N11 around Mauze-le-Mignion, where a D2 plugs into a much older S2+1 bypass and no-one has fixed it.

[TimM3-A55]

The easiest, and most compliant solution, would be to swap the signs around so the A31 crosses a 30 limit, as you would do with a roundabout where the lower speed limit is supposed to apply to the junction. Then you'd have your 40 and 50 terminals on the A31 and job done, although it'd look a bit silly having a 30 and 40/50 in the same line of sight.

I think the only other way round would be to bring the start of the eastbound 50 limit forward to the point where the eastbound carriageway widens to two lanes - it's really only 40 because of the merge to a single lane under the bridge. But that has the unfortunate side effect of raising the limit just before the traffic lights.

It is, in every sense, a mess!

That rather sums up all of that section of the A31! Although I live quite close by I hardly ever use that section of the A31, I normally join at or just east of the Sheppard and Flock roundabout, or just west of the next roundabout. Whenever I do it's always horrendous, the level crossing at the station can back traffic up to the junction making it even worse.

Having a 30 limit on the A31 through the junction would seem to be the sensible solution. It really needs remodelling and upgrading

[A303Chris]

I had no idea the A31 did that there, is that a 1950s bridge that was deemed not worth replacing? It reminds me of the N11 around Mauze-le-Mignion, where a D2 plugs into a much older S2+1 bypass and no-one has fixed it.

The whole bypass was built in the 50's as can be seen on the 1960's OS map as single carriageway.

By 1965, the road to the west had been upgraded to dual carriageway
.

By the mid 70's it was dual carriageway either side of the A287 bridge, but if IIRC it was WSC under the bridge.

The current arrangement was set up about 20 years ago.

I never realised the eastbound had dropped to 40mph, not surprising as the large 50 back yellow signs where the drop from 70mph occurs have been replaced by these.

Conversely where it increases back to 50mph , they are again small.

These must be contrary to the TSRGD and Traffic Signs Manual for dual carriageways

[Chris5156]

I never realised the eastbound had dropped to 40mph, not surprising as the large 50 back yellow signs where the drop from 70mph occurs have been replaced by these.

Conversely where it increases back to 50mph , they are again small.

These must be contrary to the TSRGD and Traffic Signs Manual for dual carriageways

I think so too - the 40mph terminal signs aren’t much bigger than repeaters. The whole implementation of that 40 limit is badly thought through and badly executed.

[JohnnyMo]

I can not see the problem, both carriageways have repeater signs just past the junction, and the side road has 30 signed.
I am sure there are single carriageway roads with different speed limits ( can't think of one of the top of my head).

Maybe a purest would say the signage could be better but IMHO it is adequate. It is not like someone is trying to get off a speeding ticket for doing 30 in a 50 zone because I only saw repeaters which were therefore invalid.

[jackal]

The easiest, and most compliant solution, would be to swap the signs around so the A31 crosses a 30 limit, as you would do with a roundabout where the lower speed limit is supposed to apply to the junction. Then you'd have your 40 and 50 terminals on the A31 and job done, although it'd look a bit silly having a 30 and 40/50 in the same line of sight.

I think the only other way round would be to bring the start of the eastbound 50 limit forward to the point where the eastbound carriageway widens to two lanes - it's really only 40 because of the merge to a single lane under the bridge. But that has the unfortunate side effect of raising the limit just before the traffic lights.

It is, in every sense, a mess!

I had no idea the A31 did that there, is that a 1950s bridge that was deemed not worth replacing? It reminds me of the N11 around Mauze-le-Mignion, where a D2 plugs into a much older S2+1 bypass and no-one has fixed it.

Along a bypass is not always the best place for a footpath and if they relocated that they could get at least S4 under the bridge. Benefits might be small, though, given the signalised junctions either side. Really sums up the A31 between A3 and M3: more bodged than not.

[Chris Bertram]

I can not see the problem, both carriageways have repeater signs just past the junction, and the side road has 30 signed.
I am sure there are single carriageway roads with different speed limits ( can't think of one of the top of my head).

Maybe a purest would say the signage could be better but IMHO it is adequate. It is not like someone is trying to get off a speeding ticket for doing 30 in a 50 zone because I only saw repeaters which were therefore invalid.

That would not be a valid defence anyway. For many years, when a 30-limit side road exits onto a 40-limit main road, there has been no requirements for a big 40 sign at that exit, as there should be a 40 repeater within a reasonable distance (there also need only be one big 30 sign on the left as you turn into that side road rather than the usual pair, with the streetlights doing the rest). I can imagine that the principle of a repeater within a shortish distance ought equally to apply in a case like this.

[Brenley Corner]

If only they could agree what do do with this junction LINK then it would help to solve the speed limit issue and the possibly the narrow bridge. An underpass has been on/off for the past twenty years.

Tony

[jackal]

If only they could agree what do do with this junction LINK

Some short sighted stuff in there, e.g.: “It isn’t A31 that causes problems in the town centre, it’s the traffic on Station Hill. You can do whatever you want with the A31 – build an underpass to rival Tolworth! But until Station Hill is addressed, it won’t make any difference at all.” If only there was some way of separating A31 and Station Hill traffic, maybe by using different grades?

[Micro The Maniac]

Having a 30 limit on the A31 through the junction would seem to be the sensible solution. It really needs remodelling and upgrading

The anti-flow control on the traffic lights mean that the 50 limit is more for amusement value anyway...

[Chris5156]

If only they could agree what do do with this junction LINK

Some short sighted stuff in there, e.g.: “It isn’t A31 that causes problems in the town centre, it’s the traffic on Station Hill. You can do whatever you want with the A31 – build an underpass to rival Tolworth! But until Station Hill is addressed, it won’t make any difference at all.” Even only there was some way of separating A31 and Station Hill traffic, maybe by using different grades?

More or less standard Surrey local politics: the idea that everyone travels by car, everywhere, is taken as an absolute and unnegotiable starting point, as is a complete inability to imagine or consider things being any different to the way they are now.

If the level crossing is the problem, and Network Rail probably agree that it is on safety grounds (they would, I think, like to get rid of all level crossings if such a thing were possible) then fine, fix that first. Raising or lowering the road are both unrealistic given the urban surroundings and the gradient; raising or lowering the railway is out of the question. So close it. Deal with the political problem of re-routing through traffic along Alfred Road to the A287, which crosses the bypass on a bridge. Voila! Station Hill no longer has tailbacks.

Then rebuild the A287 bridge to allow four lanes underneath and provide sliproads to/from the A31. Then close the signalled junctions either side.

But that involves changing something about their perfect, picturesque, untouchable town, so you can forget it!

[jackal]

More or less standard Surrey local politics: the idea that everyone travels by car, everywhere, is taken as an absolute and unnegotiable starting point, as is a complete inability to imagine or consider things being any different to the way they are now.

If the level crossing is the problem, and Network Rail probably agree that it is on safety grounds (they would, I think, like to get rid of all level crossings if such a thing were possible) then fine, fix that first. Raising or lowering the road are both unrealistic given the urban surroundings and the gradient; raising or lowering the railway is out of the question. So close it. Deal with the political problem of re-routing through traffic along Alfred Road to the A287, which crosses the bypass on a bridge. Voila! Station Hill no longer has tailbacks.

Then rebuild the A287 bridge to allow four lanes underneath and provide sliproads to/from the A31. Then close the signalled junctions either side.

But that involves changing something about their perfect, picturesque, untouchable town, so you can forget it!

It's not even that bad so far as level crossings go with that A287 bridge only 400m away, served by the aptly named Approach Road. The worst of the problems seem to be extremely localised, on 70m metres of road between the A31 and Approach Road. I suspect much of the issue would go away if they just added another lane by taking away 10 on-street parking places. But as you say, easier said than done in this part of the world.

Also, looking at GSV, it seems that there absolutely are queues going back from the A31 (rather than just from the level crossing), so it's nonsense for the councillors to claim that grade separation of the A31 would achieve nothing. It's a classic local politician fallacy that congestion is caused where the queues are rather than downstream.

[Micro The Maniac]

It's not even that bad so far as level crossings go with that A287 bridge only 400m away, served by the aptly named Approach Road. The worst of the problems seem to be extremely localised, on 70m metres of road between the A31 and Approach Road. I suspect much of the issue would go away if they just added another lane by taking away 10 on-street parking places. But as you say, easier said than done in this part of the world.

Approach Road is not really suitable as a thoroughfare... it is really just an access road to the station and its car park - albeit with access from both ends.

The two problems are the crossing, but more pertinent, the poor sequencing of the traffic lights at Henleys.

And before the anti-car brigade get too wound up, remember that that A31 is the bypass here... the A325 is the E/W through route, with A287 the N/S through route.

[Chris5156]

The two problems are the crossing, but more pertinent, the poor sequencing of the traffic lights at Henleys.

You, I and Jackal are all agreed on that. Despite the misguided protestations of the town council, a better junction with the A31 would make things much better for everyone trying to get through there, whether north/south or east/west. I don't know why they're so against an underpass or flyover. (That's not true, I do know why, but it's for reasons that have nothing to do with a rational assessment of what will improve traffic flow.)