One camera in Belfast has generated more than 40,000 bus lane fines, it can be revealed.
Situated at Donegall Square East, it is responsible for the most penalties being issued to city centre commuters.
A total of 41,054 fines have been issued there since 2015 when bus lanes were controversially introduced.
It comes as new figures reveal the number of vehicles caught driving in the lanes in the past six years has now passed the 100,000 mark.
In total, the cameras have generated 119,054 penalty charge notices since 2015.
With a £45 minimum penalty, the fines will total at least £5.3m.
If the penalty is not paid quickly, it will double, so the true cost to commuters may be much greater.
A former Lord Mayor of Belfast said the bus lanes had been "a disaster" for the city.
The camera at Donegall Square East, which runs alongside City Hall, is itself responsible at least £1.8m in fines.
Other hotspots include:
Great Victoria Street: 24,511 fines.
College Square East: 14,404 fines.
Donegall Square South: 7,224 fines.
East Bridge Street: 6,677 fines.
The figures were released by the Department for Infrastructure after a Freedom of Information request by the Belfast Telegraph.
Bus lanes were introduced in 2012 as part of the Belfast On The Move traffic plan.
There are now more than 60 bus lanes situated across 50km of the main routes in Belfast.
Since June 2015 motorists who drive in the lanes face a £90 fine, reduced to £45 if paid in two weeks.
Up to October this year, a total of 6,185 penalty charge notices were issued across the city in 2020.
That is considerably lower than previous years - but bus lane enforcement was suspended from March 25 to June 29 due to the first Covid-19 shutdown.
A record 32,274 contraventions were recorded in 2015. This dropped to 13,199 last year - but still equates to 36 a day.
The total number of fines issued in 2016 was 27,938, falling to 20,825 the following year and 18,633 in 2018.
Former Lord Mayor Jim Rodgers has long believed that the bus lanes have been a real negative for Belfast.
The Ulster Unionist councillor said confusion among drivers from outside the city about some road layouts is the reason for the high numbers of tickets being issued in certain areas.
"People visiting this city have often said to me how congested Belfast is and some have even nicknamed it 'bus' city," he said.
"You only have to look at Donegall Square West, which has become like a bus station every day of the week, including Sundays."
Anne Madden from sustainable transport charity Sustrans said the fall in fines issued over the past six years suggested motorists are more familiar with the traffic system.
"This is what the Department for Infrastructure predicted would happen," she added.
"It is unfortunate but necessary that fines have to be issued at all to enforce bus lanes.
"Bus lanes are to encourage commuters and shoppers to use sustainable modes of transport to ease congestion and reduce air pollution.
"If we all drove in our individual cars in Belfast then we wouldn't be going anywhere fast."
Ms Madden highlighted the fact that Belfast cyclists are also very dependent on bus lanes because of a lack of dedicated infrastructure for riders.
"As many as 7,500 return cycle trips are made daily in Belfast by people who could have used a car. If all these cars were using our roads they would create a 22-mile tailback, equivalent to the distance from Belfast to Lurgan," she pointed out.
The Department for Infrastructure said: "Enforcement of parking restrictions and bus lanes aims to reduce the number of illegally parked vehicles and unauthorised vehicles using bus lanes during operational hours.
"This in turn will minimise traffic congestion, improve road safety and facilitate access to property and the transport network for all users. It also enables reliable bus and taxi journey times.
"In order to achieve these benefits, it is important that appropriate action is taken to discourage those who park or use bus lanes illegally. PCNs are issued to drivers who contravene regulations, as this greatly impacts on other road users and has a knock-on effect on traffic flows.
"We would urge drivers to drive and park responsibly and legally at all times."