In-vehicle apps for assistance such as traveller information are being affected by a lack of signal on British roads.
Research by the RAC foundation found almost 4,600 miles (two per cent) of British roads have no mobile phone coverage at all, while there are 14,554 miles of road (six per cent) where there is a complete absence of 3G coverage.
An additional 111,679 miles of road (45 per cent) have only partial 3G coverage.
A 3G signal is needed to use smart phones effectively.
The black spot stretches of road – measuring 4,561 miles in total – represent 2% of the length of Britain’s road network and are to be found in 49 separate local authority areas. Those local authority areas with the most miles of road without any mobile signal coverage are:
1) Highland (452 miles of road with no coverage)
2) Powys (437 miles)
3) Argyll & Bute (293 miles)
4) Cumbria (252 miles)
5) Devon (243 miles)
6) Dumfries & Galloway (237 miles)
7) North Yorkshire (231 miles)
8) Scottish Borders (226 miles)
9) Gwynedd (172 miles)
10) Ceredigion (156 miles)
Amongst the roads which have stretches with no mobile phone signal coverage at all are the A93 in Scotland, A149 in East Anglia, A494 in Wales and A591 in Cumbria.
A further 28,975 miles of road have only partial 2G coverage meaning there are many areas where some but not all phones will receive a signal depending on the service provider.
Steve Gooding, director of the RAC Foundation, said: “Increasingly we drivers depend on our smart phones for everything from telling us how to get from A to B, to what the weather is going be, to where the congestion is.
“Yet both 3G and 4G coverage is still patchy in many areas and the chance of downloading data when we need it can often be slim.
“The concepts of connected cars and drivers is at the heart of much thinking about how we might make our travelling lives easier. But the best ideas in the world will fall at the first hurdle if there are no bars on the phone.”
And, he says, there’s a simple safety issue too.
“Most of us like to think we are always just a mobile phone call away from help but even in a crowded, high-tech country like Britain the reality is somewhat different.
“Our work shows there are thousands of miles of road along which you would not want to break down or have an accident because calling the RAC, the emergency services or even home wouldn’t be an option. Even where there is partial network coverage it might not be from your network provider.”