Nearly all of the 100 top-earning yellow box junctions in London and Cardiff are “too big”, according to a former TfL yellow box designer who has launched a national campaign.

In a study with the RAC, Sam Wright - aka the “Yellow Box Guru”- found that 98% of junctions in London and Cardiff are bigger than necessary to prevent the obstruction of a cross movement.

Sam’s findings and national campaign to change the law on yellow boxes come amid a surge in enforcement, with some local authorities, such as Kingston upon Thames, raking in more than £450,000 a year.

The Yellow Box Guru shares tricks for avoiding yellow boxes and tips on appealing fines on his website and on social media, which has sparked an unlikely following among the under-25s. 

Sam says there is no law which explicitly outlines the purpose of a yellow box, despite most people thinking it designates an area you can't stop in.

He claims this legislative ambiguity is vital in enabling local authorities to unfairly enforce tickets.

He said: “I set up my website with information for the public to help them understand what the law is, and half of my campaign is also aimed at authorities, for them to understand the law.

“A lot of people designing and enforcing boxes don’t actually know the law, as there isn’t clear government guidance on the purpose of a yellow box, and how big one should be.

“Because of the ambiguity in the law, councils can get away with making their boxes bigger, and they always hide behind a one-line response - that the box ‘complies with the legislation’.

“What I’m calling for through my petition is to explicitly state that a box should be no bigger than necessary to prevent the obstruction of a cross movement.

“This is the best way to make a change as it would force all authorities to fall into line.”

Sam says he made progress with the Department for Transport under the previous Conservative government, but has been cut off from communication since 2024.

He said: “I spoke with the Department for Transport about this in the past, and it looked like we were getting somewhere - but it’s gone off the radar since the 2024 General Election was called.

“My aim with this campaign is to bring it back onto the radar of the Transport Secretary.

“And ultimately, if I’m successful, the councils will get less money from enforcement.”

A Department for Transport spokesperson told the SWLondoner: "Local councils know their areas best, which is why they are responsible for road markings.

"Our statutory guidance makes it clear that yellow box junctions should only be used to manage traffic - not raise revenue. " 

University student Madison White was surprised to receive a £70 fine from Cardiff Council weeks after the back of her car was caught in a yellow box.

Madi took a different road home after her usual route through Cardiff was closed for road works when the person in front stopped suddenly, leaving inches of her car in a yellow box.

Two weeks later, the 22-year-old student received a £70 fine from Cardiff Council, which was reduced to £35 if paid within 14 days.

Madi was convinced there had been an error, so she immediately appealed the fine.

She said: “When I saw the picture they sent with the fine, I thought it was a mistake by an automatic camera.

“The smallest fraction of the end of my car was slightly in the yellow box - it wasn’t like I was in the middle of it, or preventing anyone from driving across the junction.

“It was a real surprise when the fine turned up, I thought it was a joke!

“Which is why I was so surprised when Cardiff Council rejected it.”

Cardiff Council upheld the fine on the grounds that a part of Madi’s car was in the junction, but allowed her to pay the reduced fee.

The student said that having her appeal rejected has put her off challenging future fines, and that other people are likely to be detered by how long it takes to hear back for a decision.

She said: “People could get caught out because it may be so long since you appealed it that you’ve forgotten about the fine and that you have to pay.

“I think it’s very unfair, especially given the amount they are fining people - it’s just not something people can afford.”

She added that her yellow box fine was relatively cheap compared to those issued on Transport for London’s ‘Red routes’ - which start at £80, and climb to £160 if not paid within 2 weeks.

Madi thinks it’s a good idea that campaigners like the Yellow Box Guru are using social media to raise awareness of the issue, particularly among younger people.

She said: “When you see it’s happening all the time and that everyone is going through the same process and getting nowhere, it makes you think this is something worth fighting against.

“But a lot of young people don’t watch the news, and if they do, it’s not about yellow boxes.

“Everyone’s on TikTok though -  even my dad!”