Tunnels are the ultimate infrastructure project, requiring some of the biggest, most advanced custom-made machines and conveyor systems ever assembled to make them work effectively, and can have an astonishing effect on the local areas surrounding them.

However, an unusual aspect of tunnels is that whilst speed is typically the main reason why they are made, in order to make travelling from one location to another faster and more viable, they are rarely ever used for racing.

The main reason for this is purely a matter of utility; tunnels tend to be constructed along busy routes which need to be open almost all of the time. Closing a road so a race can be organised is not typically seen as a worthwhile use of resources, and using railway tunnels for racing can be outright dangerous.

However, tunnels have been part of the route of certain races in the past, and there has been a fascinating and growing trend in recent years for tunnels to be used for various racing events.

The Monte Carlo Tunnel

Arguably the most famous tunnel ever used for racing is “Le Tunnel”, a stretch of road tunnel that forms part of the Circuit de Monaco, a street circuit in Monte Carlo that has hosted motor racing since 1929.

It is one of only three tunnels that has ever been seen in the Formula One World Championship along with the Detroit Street Circuit and a very small tunnel at the Yas Marina Circuit pit lane, and it was by far the longest. 

The tunnel is one of the most unique challenges on one of the most unusual tracks in motorsport history, in no small part because the level of light switches from daylight to dim tunnel lighting and back to daylight in time to face a difficult chicane.

It also has unusual aerodynamic properties, which are claimed to cost a car up to a third of its downforce, and always remains dry even during the many instances that the Monaco Grand Prix is run in wet conditions, which can cause absolute havoc.

This was the case in 1982 when during a wet weather race where every driver gambled on dry tyres, race leader Alain Prost was caught out by the soaking slicks, the wet-dry conditions of the tunnel and the dog-leg corner to dramatically crash into the barriers.

This is the most famous example of a racing tunnel, although it consists of a very small part of a race track. However, there are some races that have been run completely in tunnels.

The Tunnel Run

In recent years, as part of a growing wave of unique and unusual endurance running events, no fewer than two running races in the UK have taken place entirely in tunnels.

The first is known as Tunnel Ultra, a 200-mile ultramarathon undertaken in a disused railway tunnel loop converted into the UK’s longest foot tunnel that is claimed to be 99 per cent underground.

With minimal lighting in some areas and no lighting in others, the race is one that tests both the body and mind to extreme degrees. Barely over a dozen people have ever finished it as of 2024.

Most of the tunnel’s route is completely dark and at nighttime hours is completely pitch black, which leads to some rather strange and unusual effects on runners.

It is a unique use of a tunnel as a running course, and what Tunnel Ultra uses on purpose is likely a reason why other tunnel running events are unusual and why there has not been a dedicated racing tunnel created.

The most recent tunnel running event is The Tunnel Marathon, an adaptation of a German ultramarathon that takes place in a salt mine.

Taking place in the underground UCAP Bunker in Portsmouth that otherwise holds military-themed paintball events, it consists of a number of underground bunkers, tunnels and rooms, some of which are only six feet high whilst others are unlit.

Both hazards have meant that helmets and head torches were required equipment for the 90-lap event.

The event’s organisers have historically chosen unusual locations to run marathons, including one in a museum, along a pier, in prisons and even one up and down a multi-storey car park, which brought the organisers international attention.

Interestingly, whilst these are the two biggest in the UK, they are unlikely to be the last, with the organisers claiming that they have considered another tunnel under a river as a potential site.

Tunnels are extremely unique and amazing pieces of infrastructure, and provide a completely different experience for racing in comparison to open-air circuits or even indoor tracks.