13th March 2018 at 2:08 pm #3424LaurenEvansParticipant
The arrow combining the ahead and turn manoeuvre can be used on signs to diag. no. 877. However it can’t be used on signs with destinations. It is not described in Schedule 12, Part 5 of TSRGD 2016 but I keep seeing it used with destinations around the country for example on some new signs near East Midlands airport. Is anyone aware of any special authorisations for the use of this arrow on lane destination signs or has it just been used incorrectly?13th March 2018 at 3:47 pm #3876
I very much doubt if these signs have authorisation, so your hunch is right that they’ve been used incorrectly.
These double-headed arrows on dedicated lane ADSs date back to the old Circular 7/75, that was the forerunner of TSM Chapter 7 for layout and spacing rules. At Buchanan Computing we put them into an early version of our SignPlot software to implement this Circular, but then hid them away when TSM7 came out, showing that such arrows should no longer be used. (But they’re still there if you know where to look.)
I can see why some people are tempted to still use them to indicate a lane that has two route options ahead, but very rarely is it possible to show clearly which destinations apply to which arrow head. So a conventional map or stack type ADS, followed by a diagram 877 (with no destinations) to show which lane to use, accompanied by lane arrow markings is the best solution. Sometimes the lane arrows will suffice without the 877, depending upon how intuitive the lane guidance is, and whether any serious safety or capacity problems are caused by occasional vehicles being in the wrong lane.13th March 2018 at 3:48 pm #3877
This is an example from Manchester, which I also doubt was authorised… https://goo.gl/maps/4aQHgjBJkWq
At least in this example the confusion risk has been eliminated by extending the arrow length to separate the destinations.
It also does appear on trunk road signs! There is a set here (https://goo.gl/maps/aooT1xSRWqq) on the A627(M), which were erected well after LTN 1/94 came out. Whether or not the then HA authorised it is unknown of course.
I suspect the intention behind them is to demonstrate a lane does actually go both ways without spending extra money on a Dia. 877, or in the case of the A627(M) example, a gantry.
We have far too many situations where selecting a lane in good time is made difficult due to misleading or incorrect signs, and without a thorough design guide for ‘unusual’ scenarios this problem isn’t likely to go away any time soon.26th April 2018 at 3:48 pm #3878
The way this situation should be signed these days is by a sign using the layout shown in TSRGD Schedule 12, Part 5, Item 5, varied as appropriate, backed up with an 877 as needed, as Simon says above.
If gantry signs are present, then something along the lines of Figure 2.3, 5.2 or 5.3 from IAN 144 might be appropriate.
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