Why do cars roll up hill? Meaning of gravity hill and baffling optic illusion on Electric Brae explained

Have you ever encounterd a hill where your car will roll upwards?

These baffling optical illusions are called gravity hills.

They give the driver the sensation that your car is magically rolling uphill, when actually it is going down.

One of the most common spots for this phenomenon is Electric Brae in Ayrshire on the A719 between Drumshrang and Knoweside.

Turn off your car engine and your car mysteriously appears to roll uphill.

The small stretch of road has become a tourist attraction, with hundreds of visitors each year travelling out to give the gravity hill a go for themselves.

So why does this happen? Here’s everything you need to know about it.

Why do cars roll uphill on the Electric Brae?

Known locally as Croy Brae, this short half-mile road appears to be running uphill, but due to an optical illusion created by the surrounding landscape all is not what it seems.

The popular tourist spot sees people travel to have a go at the gravity hill for themselves.

The parking lane at the side of the road is the ideal spot.

All you have to do is place your car in neutral facing downhill and as if by magic the vehicle will roll backwards up the hill instead of rolling forward.

Locals have come up with their own theories and explanations for the road, from a buried chain of powerful magnets, minerals in the rich coastal soil, misbehaving gravity and suggestions the brae is haunted by witches.

However, there lies a simple explanation, the hill is a gravity hill, an optical illusion that tricks the drivers into thinking they are going uphill, when actually they are going down.

Influenced by the horizon line, the top of the uphill slope is actually at the bottom of the hill.

The optical illusion that the road is uphill is influenced by the landmass being on a slope.

What is a gravity hill?

The hill at Electric Brae and others like are called gravity hills.

Gravity hills are where a downhill slope appears to be an uphill one due to the surrounding landscape.

This creates the optical illusion that a car left in neutral will roll uphill, when actually it is rolling downhill.

How does a gravity hill work?

Gravity hills are an optical illusion.

The slope, although often viewed as going uphill, is actually going downhill.

The most important influence for a gravity hill is an obstructed horizon, without being able to view a horizon clearly, it can become difficult to judge a surface’s slope.

Objects which you would expect to be straight like trees, can be sloped off, adding further disorientating effects.

A study in 2003 investigated how not being able to see the horizon can impact a person’s perspective on gravity hills.

Researchers from University of Padova and Pavia discovered that without an unobstructed horizon in sight, our brains can be tricked by common landmarks such as trees and signs.

However, despite the scientific reason, many gravity hills often come with supernatural claims that magnetic forces or even ghosts are behind the phenomenon.

Where are there other gravity hills in the UK?

There are seven gravity hills in the UK.

Here is a full list of all the confirmed hills in the UK where cars will roll upwards.

• Birmingham: Harborne Walkway Harborne
• Buckinghamshire: Dancers End Lane Aston Clinton
• Essex: Hangman’s Hill High Beech Epping Forest
• West Sussex: Rogate on the A272
• County Down: Mourne Mountains on the B27
• Ayrshire: Electric Brae on the A719
• Powys: Llangattock (Crickhowell) Brecon Beacons