Emergency Diversion Route oddities

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ais523
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Emergency Diversion Route oddities

Post by ais523 » Tue Jul 26, 2016 06:36

Relatively recently (recently enough that it doesn't show up on Google Street View), there's been a profusion of emergency diversion route symbols along the A426 near the M6. Although I don't quite trust my memory on the issue, I vaguely remember five on the same sign. Anyone know what the record is? Presumably there are some very areas that would need to play host to a large number of different possible motorway diversions (the A446 seems like a promising place to look). (EDIT: Best I've found on one sign on the A446 is four, but two of them are the same and point in different directions, using road names to disambiguate. This kind-of implies that eight symbols are not enough.)

More confidently, I remember a cross-shaped such sign in the same general area (perhaps even visible from the M6?), presumably because the "official" eight ran out. I was pretty surprised to see such a sign (CBRD says they're only used for diversions for river crossings in London, which clearly doesn't apply here). Can someone confirm that I'm not just going crazy? (Also, anyone know where it leads?)

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Re: Emergency Diversion Route oddities

Post by Big L » Tue Jul 26, 2016 06:53

I recall this X but don't remember seeing one on the M6.
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Re: Emergency Diversion Route oddities

Post by ais523 » Tue Jul 26, 2016 07:04

I can kind-of do five on the A452, but I think this is cheating (as well as somewhat incomprehensible). AFAICT it means "when following hollow circle, you were aiming for the M42 so continue around the roundabout, but if you actually want the M40 you might want to use this exit as an alternative".

Re: that cross, that's the same shape/font as the one I remember seeing on the M6. Is it possible that we have a new official ninth symbol?

EDIT: We do! TSRGD 2016 lists the nine possibilities for "Indication of a diversionary route (Alternative types)" in Schedule 12, Part 11, Item 13. They're solid square, hollow square, solid circle, hollow circle, solid triangle, hollow triangle, solid diamond, hollow diamond, and cross. Presumably we'll start to see the crosses cropping up all over the place as new motorways that need new diversionary routes are found.

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Re: Emergency Diversion Route oddities

Post by Bryn666 » Tue Jul 26, 2016 08:34

The symbols are a bit of a naff system as often they're lost in the main signs and can regularly route you down horrible routes so people just ignore them anyway.

Maybe it would be more intuitive if the system had been designed to give each diversion route a number - so let's say you were diverted off the M6 northbound at J25 to rejoin at J26...

"Div. 25" signs would be more obvious than a symbol thoughtlessly glued to the sign.

In fact the French have dabbled with this in places, you see signs for 'S2' etc, which you can follow back into the motor way further on. I've only really seen it on free sections with lots of junctions however.

I believe the Germans have similar too with 'Uxx' numbers.
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Re: Emergency Diversion Route oddities

Post by Andy P » Tue Jul 26, 2016 09:54

Bryn666 wrote:I believe the Germans have similar too with 'Uxx' numbers.
Yes, Germany seems to have a very comprehensive Uxx numbering system for motorway diversions.

Example: http://www.strassenschilder.de/images/s ... eitung.jpg

I can't say from personal experience how well it works, because the only time I recall being diverted from a motorway, I didn't spot any references to the diversion number. In any case, I knew the area, and I didn't have any problems finding the way.

Incidentally, whilst looking for the example sign, I came across this German diversion sign. Although it makes complete sense, I found it amusing.
http://img01.lachschon.de/images/tyrRWTH-1061909700.jpg

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Re: Emergency Diversion Route oddities

Post by ais523 » Tue Jul 26, 2016 10:25

One thing that I noted reading the Highways England Post Incident Bulletin reports (not abbreviating that to HEPIB because hardly anyone would know what I meant) is that in order to help the roads close with traffic during a motorway closure, often the signposted route is intentionally a second-best or long-way-round route; the idea is that traffic unfamiliar with the area uses the signposted diversionary route and reaches their destination, whereas local traffic who presumably know the area use the better route and thus no single route has to bear the brunt of motorway traffic. (Drivers who are using satnavs that take road closures into account, which is very common nowadays, will be sent by the satnav down whichever route will get them to their destination fastest; this tends to be self-balancing because as a road becomes congested it will become slower.) There are also sometimes extra diversionary routes added for long-distance journeys (which might or might not be correctly signposted).

There does seem to be a lot of thought going into the diversionary routes. For example, when the M62 was closed between junctions 20 and 21 recently, the official emergency diversion route (and the one signposted at the scene) was A627(M), A664, A6193 (which is fairly obvious looking at a map), but HE also put up signs warning of delays on the A628 (predicting that a lot of traffic would try to use it to avoid the M62 closure; they were right).

Another recent closure, on the M2 between junctions 6 and 5, had a rather more interesting diversionary route. A251, A2, A249 is the obvious route when looking at a map, but as this contains sections of residential S2 it's easy to understand why HE didn't want to use it as an official diversion (although I suspect quite a bit of local traffic did indeed go that way; the official diversion thus likely had the effect of allowing as much traffic as the route could handle to use it, without trying to force too many vehciles onto it). The official diversion along the emergency diversion route, A251, A252, A20, M20, A249, is fairly absurd, but I can see why they did it (personally I'd have favoured A251, A252, A20, M20, A229 for traffic that wasn't planning to leave the M2 between junctions 5 and 3, but I understand why the routes want to send traffic back onto the motorway at the next possible junction). Interestingly, there was later a collision on the diversionary route which forced the use of the A251, A2, A249 option, which inevitably became heavily congested as a result.

(EDIT: And a pretty much outright explanation of route selection here, discussing a closure between M5 J8 and M5 J9: "Addi­tional delays were noted on local roads in the area includ­ing an unof­fi­cial diver­sion via roads between J1 of the M50 to Tewkes­bury and roads through Tewkes­bury town cen­tre. Note that this route was not offi­cial and was not pro­moted by High­ways Eng­land or any other traf­fic infor­ma­tion provider — the offi­cial diver­sion route detailed above was selected in order to avoid caus­ing the delays expe­ri­enced by road users in Tewkesbury." The official routes were M50, A417, A40 and (for traffic from further north) M42, A435, A46; the former route was the EDR signposted at the scene, the latter route was the one that HE requested that the media sugges as a diversionary route.)

From the road users' point of view, I like Bryn666's idea of having signposted alternative routes to particular junctions to allow for closures (and we're starting to see some of these crop up already, such as at the A45/A452 junction; they're typically signed using road numbers on yellow patches or entire yellow signs). They'd be fairly confusing at junctions with the roads in question, though. (The current wording of a trigger sign is "To rejoin M42, follow ▲" or the like, but being trigger signs there's no reason to worry about them being obtrusive when not in use. I guess a sign at, say, M42 J6 would have to say something like "Alternative route to M42 J5" (with the diversionary signs elsewhere just saying "M42 J5", and the trigger sign saying "To rejoin M42, follow M42 J5"). This would be a lot more expensive than the current method of just placing stickers on road signs, though, because it'd need rather more space on the signs (thus larger or separate signs); we could keep the current yellow, as it has the right connotations.

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Re: Emergency Diversion Route oddities

Post by Andy P » Tue Jul 26, 2016 11:47

ais523 wrote: ... a closure between M5 J8 and M5 J9: "Addi­tional delays were noted on local roads in the area includ­ing an unof­fi­cial diver­sion via roads between J1 of the M50 to Tewkes­bury and roads through Tewkes­bury town cen­tre. Note that this route was not offi­cial and was not pro­moted by High­ways Eng­land or any other traf­fic infor­ma­tion provider — the offi­cial diver­sion route detailed above was selected in order to avoid caus­ing the delays expe­ri­enced by road users in Tewkesbury." The official routes were M50, A417, A40 ...
Interesting. I remember following this official route when the M5 was closed overnight a few years ago. Not being prepared for the closure in advance, I followed the diversion signs, and the diversion seemed to last forever - I think there was also a temporary speed limit on the M50. I remember thinking as soon as I'd passed M50 J1 that I should probably have exited there and driven through Tewkesbury, and the longer the diversion went on the stronger that thought became. I hadn't previously appreciated just how far apart J1 and J2 are.

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Re: Emergency Diversion Route oddities

Post by Bfivethousand » Tue Jul 26, 2016 13:24

ais523 wrote: Presumably there are some very areas that would need to play host to a large number of different possible motorway diversions (the A446 seems like a promising place to look). (EDIT: Best I've found on one sign on the A446 is four
Four?????

Not even close (but at least you chose the right road) :wink:

The confusing aspect is that a solid circle also directs you up the A4091 to Tamworth whilst another solid triangle and a hollow square sends you up the A446 to Lichfield :?
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Re: Emergency Diversion Route oddities

Post by ais523 » Tue Jul 26, 2016 16:26

Bfivethousand wrote:Not even close (but at least you chose the right road) :wink:

The confusing aspect is that a solid circle also directs you up the A4091 to Tamworth whilst another solid triangle and a hollow square sends you up the A446 to Lichfield :?
I assumed there'd be fewer diversions that far north, rather than more. I'd forgotten that traffic from the M6 Toll and M42 southbound had a large number of destinations they might potentially want to rejoin and thus would need multiple different symbols each. Seven's got to be either the record or close to it, though. Now I'm really curious as to how people are directed onto the routes in question; there seem to be too many to fit onto a sign on the sliproad at M6 Toll southbound JT2 (and in fact there doesn't even seem to be a trigger sign there, nor can I see an appropriately placed MS4, so maybe the signs are put out manually).

Also, it wouldn't be the first time there'd been contradictory emergency diversion routes at one roundabout. There are some trigger signs along the M42 south of Birmingham that have been left in the wrong position for ages and are creating contradictory diversions. In trying to determine what's up with the contradictions here, I guess we could try to guess which closures would use the routes in question. The route up the A4091 to Tamworth is surely going to be for a closure on the M42 northbound between 9 and 10, and most likely goes A446, A4091, A5. One of the routes along the A446 northbound will be for a closure on the M6 Toll northbound between JT2 and JT3, and will go M42, A446, A38 (not which direction along the A38). For the other one, I originally suspected a closure on the A38 northbound north of Minworth, but that would surely be A4091, A446, A38, and the only emergency diversion symbol on that stretch of the A4091 is solid square, which aims for the M42 northbound (and thus must actually be intended for a closure of the M6 southbound between junctions 5 and 4).

The emergency diversion routes that go onto the roundabout in question from the A446 northbound are solid triangle, solid circle, and hollow square. (Solid circle also sends you the other way down the A446 at that roundabout. Come to think of it, I suspect solid circle goes along the A446 in both directions; presumably HE ran out of symbols and decided to rely on A446 users assuming that they weren't being asked to do a U-turn.) As such, the "northbound" solid circle must be the diversionary route for M42 northbound between 9 and 10 (further evidence of this is the lack of a solid circle on this sign, meaning that the diverted traffic comes from the M42 and/or M6 Toll rather than further afield). The "southbound" solid circle eventually leads to M42 J6 and then disappears, so I guess that M42 J6 is its destination (meaning in turn that it's intended for some kind of closure of the M42 southbound).

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Re: Emergency Diversion Route oddities

Post by kit » Tue Jul 26, 2016 16:35

ais523 wrote:There are some trigger signs along the M42 south of Birmingham that have been left in the wrong position for ages and are creating contradictory diversions.
There doesn't appear to be great co-ordination at closing signs. This one has been left open for so many years the bottom panel has fallen off so it is no longer closeable!

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Re: Emergency Diversion Route oddities

Post by Bristol » Tue Jul 26, 2016 18:42

In addition to the official symbols, the Bristol area has a stylised suspension bridge for diversions when the original Severn crossing is closed.

Although, that "diverted traffic" sign is for ... a nighttime closure of the Severn bridge, I think (there's an advance warning sign the other side of the roundabout).

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Re: Emergency Diversion Route oddities

Post by wrinkly » Tue Jul 26, 2016 19:41

Bristol wrote:In addition to the official symbols, the Bristol area has a stylised suspension bridge for diversions when the original Severn crossing is closed.
You could argue that that's more like a stylised cable-stayed bridge, so appropriate for the second Severn crossing.

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Re: Emergency Diversion Route oddities

Post by Big L » Tue Oct 03, 2017 18:15

Bfivethousand wrote:
ais523 wrote:...Best I've found on one sign on the A446 is four
Four????? Not even close (but at least you chose the right road)...
I found a six on this sign.
Same place, older sign.
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Re: Emergency Diversion Route oddities

Post by Stevie D » Tue Oct 03, 2017 19:09

Not sure what to make of the fact that even with 6 diversion symbols, they still needed a "Diverted traffic" sign in front of it...

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Re: Emergency Diversion Route oddities

Post by Big L » Tue Oct 03, 2017 20:09

Stevie D wrote:
Not sure what to make of the fact that even with 6 diversion symbols, they still needed a "Diverted traffic" sign in front of it...
That was still there today.
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Re: Emergency Diversion Route oddities

Post by Arcuarius » Wed Oct 04, 2017 13:30

Stevie D wrote:
Not sure what to make of the fact that even with 6 diversion symbols, they still needed a "Diverted traffic" sign in front of it...
Might as well have "All routes" in a yellow panel :lol:
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Re: Emergency Diversion Route oddities

Post by SteveA30 » Wed Oct 04, 2017 16:36

Far too confusing trying to look through that lot while negotiating a rbt. Easy to forget which one you saw earlier. Just put the destination on the portable sign, for each diversion, when required. Applicable everywhere.
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Re: Emergency Diversion Route oddities

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Re: Emergency Diversion Route oddities

Post by Stevie D » Wed Oct 04, 2017 20:55

SteveA30 wrote:Far too confusing trying to look through that lot while negotiating a rbt. Easy to forget which one you saw earlier. Just put the destination on the portable sign, for each diversion, when required. Applicable everywhere.
Really? Do you have any idea how many signs would be required?

To take a couple of examples nearby, picked for no better reason than I GSV'd a local motorway junction to see what was there.
A1(M) J43 northbound – to rejoin, follow ◊. That symbol then appears on 10 ADSs and 5 flag signs to get motorists back on the motorway.
M62 J32a westbound – to rejoin, follow ○. That symbol then appears on 20 ADSs, including about half of them being motorway gantries, and 6 flag signs to get motorists back on the right motorway.

There are hundreds of motorway junctions, and for each one there are two directions. That means over a thousand diversionary routes. If each of them has 15 signs needed along the route, that's about 15,000 temporary signs that need to be made and stored ... and then they will often need to be deployed just at the time when the roads are completely chuggered and you need every spare person on the scene. That is a colossal waste of resources and manpower, as well as being inherently impossible to roll out effectively in an emergency – using the diversion symbols really is a no-brainer.

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Re: Emergency Diversion Route oddities

Post by Conekicker » Wed Oct 04, 2017 20:59

nowster wrote:One for the M60: https://goo.gl/maps/yjTFJhqwjx62
So you can go ahead or right and still be on the diversion route.

Which genius thought that design was in any way, shape or form appropriate?

Edit: especially as a little further along, one is confronted with this:

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