Use cases for digital road signs

We’re getting excited about the development and adoption of in-vehicle signage (IVS) for drivers. Eloy has one of the first end-to-end working models for delivering road management alerts to drivers via vehicle infotainment systems both visually and, importantly, via audio. On the back of this, we have spent time discussing the suitability of these solutions and how they should be applied to the road. 

1. Alerts where alerts are not possible

One of the obvious use-cases for IVS is putting signs in hard-to-reach locations quickly. For example, if a road becomes flooded and unsafe to drive on, a warning sign could be added instantly, rather than waiting for a temporary physical sign to be placed. 

Permanent digital signs could be created instantaneously too, and at far lower cost. 

However, there are additional benefits above and beyond speed-to-deliver and cost savings. Digital signs can be variable, and whilst this is another cost saving compared to installing variable signs in locations, it also gives the flexibility to alter what you see and how you hear it. 

One of the problems with motorway signs is that they have been designed to hold a maximum number of characters, which means you end up with abbreviations such as “10mns to J15”. With digital signs it is possible to transmit much longer messages and more detailed information to drivers. 

We can also place digital signs in places that would normally be hard to reach, such as in isolated locations, near cliffs or landslides, or on undulating or winding roads. Here, placing physical signs may be dangerous or even impossible, but a digital sign is only limited by the connectivity of the internet. 

2. Alerts where there is too much information

Our first example was showing how digital signs can be used to add information where it isn’t present or is limited – the “too little” argument. There is also the “too much” argument. 

Physical road signs need to be placed in locations where all road users can see them. That means that signs for heavy-goods vehicles, public transport such as buses and taxis, motorcycles, scooters, and bikes, and private cars are all visible to all users of the road. 

Confusing Road Signs

Which way am I meant to go?

Having too many signs has two major weaknesses. First, it is distracting. A driver may struggle to find the information that is relevant to them and in doing so may need to take their eyes off the road for too long. Secondly, it isn’t always obvious which is critical information and which is advisory information. It would be much easier for a driver to follow a single “Go Here” sign, rather than trying to process and decide between relevant and irrelevant information. 

This is where IVS has an additional benefit. They can allow us to reduce the signs on the road and create tailored in-vehicle messaging for each type of driver and vehicle, ie a lorry driver would see specific messages that differ from a set of signs shown to a family looking for a car parking space. Knowing the driver’s route can also enhance customisation of message. 

Real world evidence supports the theory that roads may be safer without a multitude of signs, allowing drivers to focus more on the road layout and pedestrians. Carefully limiting the IVS information that is presented to a driver so they have only the information they need to get to their destination, may make the roads safer for all. 

3. Audio over visual

With IVS, we have a preference for audio over visual alerts for drivers. We have stated above that too many physical road signs can be distracting, so it would be foolish to then load a vehicle with more visual alerts encouraging drivers to look at a screen rather than keeping their eyes on the road. 

We think high-quality audio announcements combined with a simple graphic on the navigation display, such as a speed limit sign or text message, is the best way to present information to drivers. 

Although some automakers are investigating using IVS for advertising, we think this could be an extra distraction for drivers and will be interested to see the legal implications of this in the UK. 

4. Legal structures

Legal precedents will need to be set as we move from physical to digital road signs. We’re certain that Mr Loophole will be looking at the small print too!

The other issue is that there is not a centralised, accurate record of where all road signs are currently placed. Highways England keeps a record for motorways and A roads, but there are separate traffic regulation orders for speed limits and weight limits which tend to be kept on paper and separately across all the different Local Authorities. 

Further, not all road signs are where the paperwork says they should be as new signs often get put on existing poles nearby rather than erecting a new post to display them in the exact location. 

For an IVS-based signage system, although the digital database would be a single source of truth, there are still other factors to take into consideration, such as internet connectivity, and where and how a driver receives information about a change in speed limit for example. 

We also suspect that there may be a lack of usable evidence as it could be hard to prove that an in-vehicle alert was either triggered or viewable. We envisage drivers with good lawyers hiding behind defences such as ‘there must be bugs in the system’ or ‘my internet stopped working’. Whilst we could install additional recording and record keeping devices, this would be prohibitively expensive and also raises privacy concerns.

Demo of IVS with a single lane closure on a 2-lane highway. 

As a result, we expect IVS to be mostly informational or to provide supplementary information to existing physical road signs. 

Informational signs can be quite broad and include critical warnings such as dangers ahead – but there is no requirement for drivers to follow the recommendation in either the current Highway Code or with any proposed changes that could include IVS. 

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