The bright lights of Coventry

The Coventry Ring Road is already one of the most unusual (and, depending on taste, exciting) roads in the UK. In recent years it's acquired something no other road has - fully electronic direction signs.

It's high time we had a look at these signs, so let's make a visit to the edges of Coventry city centre. They were installed in late 2015, with many of them replacing ordinary advance direction signs on the Ring Road itself. Others are positioned in addition to existing signs on approaches to the city centre. They are thought to be manufactured by a company called Swarco.

They're intended to combine display real time parking and event information with regular direction signs, and if they work, Coventry City Council are hoping they can reduce the time it takes people to find a parking space and so reduce vehicle miles in the city centre. In normal operation they display general direction signs, but can dynamically show information about the status of a car park (like a giant, 21st century version of the standard electronic parking signs in many cities), or show information about road closures and delays, or indeed anything else that might be useful.

That makes them considerably more ambitious than any other variable message sign in the UK, as far as we're aware. But do they work?

It's certainly impressive how much the signs can be made to resemble standard direction signs, and indeed how much information can be shown on a single panel. The standard black-on-white colour scheme has been reversed to show white-on-black, with the layout, arrows and symbols looking reasonably accurate. Perhaps the main criticism that could be levelled against them is that there isn't quite enough detail to allow for a version of the official Transport lettering to be used, as it is on the newest motorway MS4 signals, so legibility isn't perfect.

The sign shown above replaces the advance direction sign for junction 7 on the anticlockwise carriageway of the Ring Road, and - like almost all its advance direction signs - it's mounted on one end of a gantry over the opposite carriageway.

Some of the signs are even more adventurous in layout.

At junctions where primary routes meet the Ring Road, the capability to render graphics in full colour is used to show a green panel, and in the example above that even includes a blue patch for motorway numbers. Black pixels are used to outline white and yellow text for better legibility against the coloured and illuminated background.

The Ring Road itself is actually a primary route, so all its signs should be green, and indeed all the advance signs these panels replaced were green. Presumably a decision was taken not to use the green background everywhere, as white-on-black is far more legible, and instead to use it sparingly to highlight the junctions with major roads.

The new signs aren't without problems, though. As the picture above shows, the angle at which the sign can be properly read is relatively narrow, and to either side - or from below - the picture starts to disappear.

Many approaches to the Ring Road also have new electronic signs to relay parking and event information to motorists approaching the city centre. The one shown above is very probably the largest variable message sign ever to be installed on a B-road.

The viewing angle problem becomes more acute when the sign is this big, especially when - as in this case - it's installed on the inside of a curve and partly screened by trees. Approaching traffic has very little opportunity to read the masses of information on the sign between the trees obscuring the view, the restricted angle at which the graphic can be seen and the sub-optimal text rendering that makes it slower to read than a conventional sign. In fact, when I drove past this sign for real, all I saw was the roundabout symbol - and then it was gone.

Too much information?

The other unfortunate fact of these signs is that they routinely alternate between several messages - in the examples above, you can see the direction sign is switched for an orange-coloured message about a future road closure. Switching through two or more messages like this is often called "paging". And this is exactly what they are supposed to do: by replacing regular direction signs, Coventry was hoping it could convey much more information to drivers and therefore make them more useful.

The trouble is they're not allowed to. In January 2015 the Department for Transport issued Traffic Advisory Leaflet 01/15, the most recent advice setting out policy on variable message signs for all highway authorities. Amid several pages of ordinary text, one paragraph is so important that it appears in bold, red letters:

It is unlawful to display messages that require the use of multiple displays (“paging”) or scrolling text.

That would imply that all Coventry's electronic signs are, routinely, unlawful - and to make them lawful you'd have to choose between having a direction sign or having messages about events and road closures, at which point you have either abandoned your system of advance direction signs or you've abandoned the reason you spent £1m on electronics.

Variable message signs "paging" through multiple screens of information may be unlawful but it is, of course, so common as to be entirely unremarkable, especially on portable roadside signs that are used to give advance notice of roadworks. We make no comment about whether it should or shouldn't be legal, or about how widespread the practice is. But it does seem fairly remarkable, and worth recognising, that Coventry City Council appear to have secured £1m of European Regional Development Fund money to install a whole system of electronic signs across the city that can only achieve their stated aim to combine direction signs with real-time information by operating unlawfully.

Away from the legalities, and setting aside quibbles about the angles at which the text on the signs can be read, Coventry's new signs are extremely interesting. This is a highly novel and experimental use of variable message signs and a first attempt can rarely be expected to get everything exactly right. The concept, though, is quite brilliant.

Leading the way

In a city centre, the best route to a destination can change from one hour to the next as car parks fill and empty, traffic builds up and clears, roads are closed or blocked, and timed delivery and parking restrictions begin or end. Coventry has particular issues managing traffic flows, with major events like Motofest regularly held in the city centre and popular destinations (such as Ikea, traditionally an out-of-town retailer that attracts congestion-inducing volumes of customers) right in the heart of the city. Fixed direction signs simply can't cope with that.

The sort of variable message signs we're used to, with changeable numbers of parking spaces or rotating panels to direct traffic one way or another, can help. But what if the road signs right across the city could be changed at any time, to show any combination of directions, destinations and information, to give people the most appropriate information about traffic and events? What if every sign could be reconfigured on the fly?

Coventry is trying something new, something that doesn't easily fit into any of the categories that other road signs fall into, something that wasn't even contemplated when the regulations governing fixed direction signs or Variable Message Signs were written. It might yet turn out to be a useful way of managing traffic in cities across the UK.

We should perhaps expect some misfires in this first attempt - but we should also be watching it closely to see whether it has the effect that Coventry City Council are hoping to see, and whether other cities in the UK and elsewhere will decide to follow suit.

You might enjoy CBRD's articles about the Coventry Ring Road and about experiments with early variable message signs.