Wednesday, 26 August 2009
In one of our previous articles "British Metric Road Signs: An overdue changeover", we added our voice to calls for metric road signs to appear in the UK as soon as possible. But what would the speed limit signs look like? We are going to explore what British speed limit signs will look like in this article.
In our next article, we will suggest how we can improve the British speed limit and speed related signage further, make them more consistent with international norms, and suggest some new signs. As a result we can reduce the need to have speed limits for everything, and potentially reduce the number of signs.
Maximum speed limit signs (Compulsory change)
The speed limit signs are shown below:
It is possible for 30 km/h or 40 km/h signs to be used as is on actual road signs (if these are used, then a 50 km/h sign must be used on exit). However, it is expected that 30 km/h and 40 km/h speed limit roundels are far more likely to appear within zone signs especially 30 km/h zones and within urban areas.
An example speed limit of 80 km/h in actual use might look as shown below:
80 km/h speed limit
Minimum speed limit and end of minimum speed limit signs (Compulsory change)
Minimum speed limit 50km/h (left); End of minimum speed limit 50 km/h (right)
The minimum speed limit and end of minimum speed limit signs are shown above.
Advisory speed limit (Minimum change)
Speed limit zones (Compulsory change)
End of speed limit zone (Minimum change)
Road markings (Compulsory change)
One place where the 50 km/h is also necessary is on urban dual carriageways where the maximum urban default speed limit (50 km/h) applies, and it is necessary to repeat these as well. In addition these markings are essential on roads through sites of special scientific interest (SSSI) such as the New Forest, for obvious reasons.
Converting the road painting 30 mph to 50 km/h would surely just involve burning off the paint for 3, and painting 5 in its place.
Variable speed limit signs (Compulsory but could be deferred until after metrication)
These will also need to be reconfigured (so long as 3 digits are supported - otherwise replaced) to support 3 digit speed limits (100 km/h) or higher – although the first digit will always be a 1. The numbers could always be condensed, if possible and required. This change affects electronic advisory speed limits, and variable speed limit signs.This change can always be deferred until after metrication (especially if electronic signs need to be replaced) by doing either of the following:
- Suspend all variable speed limits, and only reinstate for those motorways which have had their electronic speed limit signs converted.
- Alternatively, temporarily only support variable/advisory speed limits up to 90 km/h until all are converted.
Speed limit changeover
Well before the speed limit changeover, default speed limits for various classes of vehicle need to be reviewed, as will all posted speed limits in force. This is because the speed limits in miles per hour need to be converted to the appropriate km/h speed, and adjusted afterwards to take into account local conditions (e.g. schools, major accident blackspot) if required.As part of the changeover itself, kilometre day (or “K-day”), the speed limit signs will need to be changed rapidly for safety reasons. Ideally this should happen overnight. It could be spread out over a weekend as well, but the best is overnight. This is not like distance and other signs which do not have any safety issues and whose conversion can be spread out over a longer period.
In the months leading up to the changeover, there needs to be a short sharp publicity campaign, to leave people in no doubt that after a certain date, speed limits will be metric.
It would be a big job to change all of these things but it needs to happen. Looking at these pictures it would not take a lot of getting used to if the signs were to be changed.
ReplyDeleteI'd be surprised if our variable signs don't already support 3 digits, as they use a matrix style rather than preset figures or 2x7-segment, so other matrix type warnings can be shown. Also, it would make the most economic sense to buy in the already mass produced continental type, as used - at the very least - in Germany for several years. And hopefully the DoT will have looked to the future with this kind of change in mind.
ReplyDeleteI've also often thought we could do with adopting 25mph (or, 40k) limits for parts of towns and cities where a speed reduction would be warranted, but the distances involved make 20mph (or 30k) a bit harsh. Limits posted at that level are common throughout europe and the rest of the world, including Japan, Australia, Canada, USA... for some reason the UK and Ireland - even post-metrication! - have ignored it, though. If you draw a very simple graph using the figures in the "at 40mph, there's an 80% chance I'll die..." kill-your-speed advert, the line crosses "0" (as in, everyone lives) at around 26-27mph. Also, we don't plump just for 30 and 50mph limits, so why do it with km/h?
As a slight speed freak (modern cars can cruise safely and economically at much more than 70mph, and increasingly incorporate driver aids to assist this, so why not allow it?), I'd like to see us incorporate the sort of limits and stratification used in Germany, Italy or Poland. 30-40-50-60k in towns (and occasionally 70) depending on road class and situation, with a 50 default (60 overnight? :), 100k on single carriageways out of town, 110-120 on regular duals, 130-140-150 on motorways. There's hardly any car that can't easily maintain 150k these days, whilst managing 35mpg or better even so. There's provision for it in the Italian regs, Poland is actually at 140 right now, and it gives much more flexibility in regulating congestion and slowing traffic on approach to an accident (or a dangerous stretch); if normally you're allowed to run at up to 90-ish mph (there would be emphasis on this being the maximum permitted speed, and that cruising at a lower speed, within your own abilities, and out of the way of faster traffic was the generally recommended option; though my own car can run to 200k or beyond, it's a lot happier/quieter/more economical at about 105...), then a restriction bringing you down to 75, 69, 62 where that was actually as fast as you could safely go would carry a little more weight... when in the former two cases right now you wouldn't see any additional warning to the normal 70mph limit.
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DeleteMy suggestion: 50/60 for built-up areas, 90/110 outside them (depending on number of carriageways), 120 on expressways and 130-170 on motorways. All speed limits are given in km/h, not mph. View also UK Metric Association.
DeleteYour open road speed-limit sign (//) is an internationally owned sign with its legal meaning held in The UN Convention on Road Traffic as "END OF ALL LOCAL PROHIBITIONS IMPOSED ON MOVING VEHICLES".
ReplyDelete@Anonymous 16 August 2011 21:57 - Well spotted, actually I am suggesting that this "End of all local prohibitions imposed on moving vehicles" replace the existing "open road speed limit", in order to conform with the international norms.
ReplyDeleteAs far as I'm aware, the current "National speed limit" sign is something specific to the UK, whereas the international definition is that it's the end of all restrictions including speed limits (although I believe the default speed limit still applies).
A well-argued, comprehensive proposal.
ReplyDeleteOne additional change I personally would recommend would be to use a narrower typeface for speed limit numerals, similar to that used by Ireland, in addition to the km/h legend. Not only would this make it easier to fit 3 digits onto signs without compressing them horizontally, it would help make the new signs appear unmistakably different from the old ones, lessening the chances that motorists might absent-mindedly 'revert to type' and misinterpret familiar-looking "30", "40" and "50" figures as mph.
Fortunately, there is already another typeface used on road signs that happens to be almost exactly the same as the Irish alternative: 'Motorway Temporary'. It's true that it's currently only authorised for route numbers on Motorway roadworks signs, but the authorisation could easily be extended to speed limit numerals by the addition of a few extra words to TSRGD Regulation 13(6).
See an example here.
Obviously, its light-on-dark counterpart, 'Motorway Permanent', could easily be used for minimum speed limit signs with tweaks to Regulation 13(5).
Going further with the Irish example, taking the opportunity to do away with the ambiguous 'National Speed Limit' sign and replace it with explicit numeric signage is also an option, although it would incur further costs, not only in the replacement of existing NSL signs but also in the installation of additional numeric signage at every transition point between NSL single and dual carriageways. I'm not sure whether or not it would be worth it.
@Hughster - Thank you, and thank your for your comment. Excellent point regarding the speed limit numeral typeface - and what you recommend sounds very good, and would be unambiguous. Nice designs too btw, and I think Motorway is a very good choice.
ReplyDeleteAnother possibility could be to use a font similar to the German Mittelschrift (medium spaced lettering) and Engschrift (narrow spaced lettering) which also looks kind of like Motorway in my opinion - but I am not sure if it is worth creating a whole new font or two new sets of fonts - far easier just to authorise an existing font. I think that if we were to create a new font the new speed limit font could be called "Speed Limit" or something like that.
I would now personally favour getting rid of the NSL if we could too, yes I do wonder if it would be worth it costwise, but a very good suggestion, and maybe part of a separate exercise. Would certainly make things clearer.
Actually, I am in the process of preparing a PDF document with what I have written about road signs (with view of sending to the DfT, or using in consultations) - if it's okay with you, I was planning on including your comprehensive speed limit sign example image in my PDF.
@Tahrey - Thank you for your comment too, and yes I agree that we could consider having 40 km/h limits in urban areas which could improve safety, and I too would like to see stratification of speed limits - very good suggestion as well. Unfortunately, I think this would only be considered as part of a general speed limit review, which would only really happen with going metric I think.
@theglob: I'm very glad you like it. I would be more than happy for you to use my graphic in your submission to the DfT. Let me know if you would like it in a higher resolution and/or vector format.
ReplyDelete@Hughster - Much appreciated. I will definitely include your graphic in my submission.
ReplyDeleteI think your graphic is fine as is. But of course if you have a link to a high resolution image, that will be super.
Unfortunately I don't yet have a dedicated email address for my blog, sorry about that.
Please find a higher resolution version of the image HERE.
ReplyDeleteThanks Hughster, I'll be sure to add this high resolution image you have attached to my document (which is currently in progress). Apologies for the delay in replying.
ReplyDelete"attached" should read instead "for which you have given the link". Too bad one can't correct already published comments.
ReplyDeleteAre you going to post this PDF online? I'd be interested to read it?
ReplyDelete@Anonymous (8 November 2011) - Yes, I will post this PDF online. The first draft is currently work in progress and I aim to post this as soon as possible, in its own article. I invite you, along with everyone, to read it and give your feedback.
ReplyDeleteAfterwards, I will produce a final draft for submission to the DfT.
Along with filter arrow improvements, I suggest writing a post about improving traffic lights, like switching the meaning of flashing amber lights to being not that you are allowed to proceed after pedestrians have cleared a pelican crossing, but an intersection that is managed by priority signs and give way signs. This is also part of the Vienna Convention.
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ReplyDeleteI suggest 30 km/h zones in the built up area in the low volume areas where you are going to be mixing cycling and motor vehicles, they would be small roads with no reason to need to use them unless they are actually needing to go there.
ReplyDelete50 km/h for the bulk of urban main roads. Separated from pedestrians and cyclists, mostly crossing other traffic with priority over side streets, traffic lights or roundabouts, relatively small roads up to roads with 2 lanes in each direction.
Some main urban corridors, for example a major bypass of a small town or a main route linking completely different areas of town, could be 70 roads. There wouldn't be at grade cycle or pedestrian crossings, there wouldn't be accesses to 30 km/h roads, and there would be some clear zone space on either side and normally a divide between the two directions although up to 70 it's OK to not do that.
In the rural areas now, I suggest 40 for those small country lanes, they're narrow anyway and they should be quiet. Side roads can come out of nowhere, and you need to mix with agricultural vehicles, cyclists and pedestrians. 40 zones work well here. Traffic calming would be raised junctions with no assigned priority, sometimes on the wider (wider than 4 metres) roads, a pair of dashed white lines used for optical narrowing should work here. If there is more than about 2000 PCU/d, a cycle path is required.
For main rural roads, 70 km/h is a good speed. Using paint and rumble strips to divide the two directions, sometimes a raised curb, it assures a high likelihood of survival in a head on crash.
For expressways, typically single lane roads with a raised barrier, like the metal crash barriers, maybe high tension cables, and other motorway like roads that don't quite meet motorway standards in some way, would be what the Dutch call autowegen, and be 100 km/h roads.
Roads that are fully motorways would usually have a speed limit between 100 and 120 in the built up area and 130 km/h in the non built up area. Some 100 limits would be needed for noise reduction, but mostly 120 works for the urban motorways.