Bristol Street Motors has mapped out 12.9 miles of abandoned roads throughout the UK, including 12 in England, five in Scotland, two in Wales and one in Northern Ireland. At £12.1m per mile, the roads represent a total outlay of £156.12m if they were built today.
Once thriving highways, the roads now lay dormant and are slowly being reclaimed by nature. Below are the 10 longest and most expensive abandoned roads that we found. But you can also visit our interactive map to discover even more.
Located in county Argyll, a stretch of old road running adjacent to the current A83 is the longest and most expensive abandoned road on our list.
Abandoned in 2009, this 1.95 mile long and winding road moves through the Scottish Highlands, passing Loch Dubh.
Coming in at 15.64m, this abandoned road was replaced by the modern S2 route way back in the 1930's.
Now beginning to be reclaimed by nature, the road was abandoned in 2011 when the new Hindhead Tunnel was built to replace it.
The old Duartmore Bridge was abandoned when the new bridge was built in 1979, which spans a much wider channel for cars to pass each other.
At the cost of £10.53m if it was built today, the old A33 was abandoned when the M3 was completed through Twyford Down.
This road running adjacent to the A2 was abandoned in 2009 when the A2 was rebuilt into a new alignment.
Now boarded up to stop traffic accidently using it, the road running along Belfast International Airport was abandoned when the A26 moved to a new alignment.
This road used to be part of the A23 before it was realigned to allow traffic to pass villages to the north.
Once the Puckeridge bypass was opened in the 1970s, this old road was abandoned. It's still occasionally used for storage of maintenance materials.
To find out the cost of constructing a single road lane, we averaged out the cost per additional lane mile for 8 road projects in the UK since 2017 including:
The cost of each project can be found here. The average cost per additional lane mile for those road projects was £6.05m. We then doubled that number to give us the cost of a functioning road with a lane going in each direction - £12.1m per mile. This figure was then used to calculate how much each abandoned road would cost if they were built today.
*Images of the UK's abandoned roads were sourced from SABRE: The Society for All British and Irish Road Enthusiasts.
It's not only the UK that has its fair share of abandoned roads. Bristol Street Motors has picked out three jaw dropping examples from around the world, coming to a combined cost of approximately £22.04m if they were built in the UK today.
Cape Town's Unfinished Bridge is an incomplete section of motorway that looms over the city. Originally it was meant to be part of the Eastern Boulevard Highway, however due to budget constraints at the time, the unfished structure was abandoned in 1977.
The Sideling Hill Tunnel was abandoned in 1968 due to a realignment of the surrounding motorways. Users complained that the tunnel caused bottlenecks and slowed down traffic.
Sometimes referred to as the Ominous Bridge, this abandoned overpass is located in Columbus, Ohio. According to local reports, this overpass was closed sometime in the 1990s due to a reconfiguring of the streets.