Central London Congestion Charging, United Kingdom.

The introduction of the Central London Congestion Charging scheme has always been a controversial decision, since it was first introduced in February 2003 to discourage traffic congestion in central London and push people towards public transport.

Several commentators have doubted its effectiveness but its keenest proponent, the London Mayor Ken Livingstone, promotes it as a success, as he did in an article in the Guardian newspaper in February 2007 where he commented: “Each day in 2006 there were almost 70,000 fewer vehicles entering the charging zone compared to the number that had been entering each day before charging began. The amount of traffic entering central London during charging hours has been cut by around 20%… It has contributed to the growth of cycling, with more people than ever before travelling by bike – there has been a 72% increase in the number of cyclists on the capital’s major roads since 2000.”


The congestion charge is enforced within a definite road traffic boundary in the City of London. When initially introduced in February 2003, motorists were charged £5 a day to drive through London between the hours of 7am and 6.30pm. The charge is enforced by a network of cameras situated at entry and exit points to the charging zone and at key locations within the zone itself.
“The amount of traffic entering central London during charging hours has been cut by around 20%… It has contributed to the growth of cycling, with more people than ever before travelling by bike.”

The cameras record images of traffic and send them to a central processor to have their number plates read and checked against the list of vehicles that have been paid for. Unless a pass has been purchased in advance or is bought before midnight on the day of travel, the vehicle’s registered owner will then be forced to pay a fine. The charge can be paid via internet, a paypoint at a designated retail outlet, call centre or by mobile phone. At the moment the web payment option is used by 28%, paypoint by 28%, SMS by 23% and the call centre by 14%.

A novel second chance for drivers who forget to pay by midnight of the day they travel into London is the Pay Next Day scheme. The charge is increased to £10 but the driver has until midnight of the next day to call the Transport for London call centre to pay and avoid a penalty charge notice.


In February 2007 the congestion charge was increased to £8 per day and the hours were reduced by half an hour to 6pm. The hours were reduced to stimulate the theatre, restaurant and bar trade in the city, which according to Ken Livingstone had not been affected by the earlier introduction of the congestion charge.

Livingstone had said in 2003: “I can’t conceive of any circumstances in the foreseeable future where we would want to change the charge”. In May 2006, in a live TV debate, he supported a rise in the charge to £10 by 2008. An increase in charges is likely but this will now be calculated according to the carbon dioxide emissions of the vehicle, with four wheel drives (4X4s) and larger sports utility vehicles expected to pay £25 per day.


There are several groups of users and vehicles that are exempt from the Central London Congestion Charging scheme. These include disabled drivers, licensed taxis, minicabs and public service vehicles, motorbikes, mopeds and scooters and emergency service vehicles. Also, residents in the congestion charging zone pay only 10% of the charge (£4 a week instead of £8 per day) and cars that are diverted into the zone will not be charged so long as they do not deviate from the diversion.

In addition to this, ‘green’ cars using alternative fuels (gas, electric, fuel cells and bi/dual fuel vehicles) are exempt from the charge. When the congestion charge becomes based on emissions, owners of larger polluting vehicles living in London will receive no discount and will have to pay the full £25 per day; while the list of vehicles with exemption because of low emissions may well be extended.


The congestion charging scheme aimed to reduce traffic in Central London by 10–15% and time spent in delays by 20–30%. Prior to the introduction of the scheme, 40,000 vehicles per hour drove into the congestion charging zone between 7am and 10am; between 7am and 6.30pm, approximately 250,000 vehicles made 400,000 movements into the zone.

Accordingly the scheme has had a positive impact, as each day in 2006 there were almost 70,000 fewer vehicles entering the charging zone compared to the number that had been entering each day before charging began. The amount of traffic entering central London during charging hours was cut by around 20%. Congestion charging also raises £130–150m a year in revenue (an estimated one third of this in fines), which is used to improve public transport in London.


The original congestion charging zone was enclosed within a boundary formed by the Inner Ring Road which consists of: Marylebone Road, Euston Road, Pentonville Road, City Road, Great Eastern Street, Commercial Street, Tower Bridge Road, New Kent Road, Kennington Lane, Vauxhall Bridge Road, Grosvenor Place, Park Lane and Edgware Road. This gave the congestion charging zone an area of 8 square miles (21km²) – 1.3% of the total area of Greater London. There were 203 entry and exit points to the charging zone.


The western extension of the congestion charging zone was introduced on 19 February 2007, effectively doubling the original area. The boundary of the enlarged zone starts at the northern end of Vauxhall Bridge and (travelling in a clockwise direction) heads along the northern bank of the River Thames as Grosvenor Road, the Chelsea Embankment and Cheyne Walk.

From here, it heads north, along the eastern edges of the Kensington and Earl’s Court one-way systems (classified as part of the A3220), encompassing Edith Grove, Redcliffe Gardens, Earl’s Court Road, Pembroke Road, Warwick Gardens and part of the Addison Road, before continuing to the A40 Westway as the Holland Road and the West Cross Route.
“The western extension of the congestion charging zone was introduced on 19 February 2007, effectively doubling the original area.”

The boundary then includes parts of North Kensington, but the actual boundary is defined by the West London Line railway track, which runs between Latimer Road (inside the zone) and Wood Lane (outside the zone), until Scrubs Lane, before turning east, following the GWR line out of Paddington towards Ladbroke Grove.

Here, the boundary follows the Grand Union Canal and rejoins the existing zone at Edgware Road after skirting Paddington, by way of the Bishop’s Bridge Road, Eastbourne Terrace, Praed Street and Sussex Gardens.

Transport for London (TfL) have defined some free through routes, where drivers do not have to pay the charge. The main route is defined by the western boundary of the original zone Vauxhall Bridge Road, Grosvenor Place, Park Lane and Edgware Road, with some additions around Victoria. The Westway is the other exempt route.

Extensions to the north, east and south of the city centre were also considered but were not taken forward since their traffic problems were not considered as severe as the west, and in the east and south, public transport provision is not yet considered to be good enough to support congestion charging. For the western extension significant increases in bus service capacity were introduced.


Preliminary results of traffic surveys show that two weeks after the expansion traffic in the extended part of the zone decreased by 13%, which was well within the Transport for London (TfL) predictions of a 10–15% reduction. This represents approximately 33,000 fewer vehicles entering the expanded area of the zone.

So far the predicted 2% increase in traffic in the original section of the charging zone has not come to pass. This was expected because with 78,000 households in the new part of the zone being eligible for a 90% discount on the daily charge it was thought some people would decide to drive instead of taking public transport. Presumably, parking charges in central London have acted as enough of a deterrent to using the car.


There are two types of analogue cameras within the central congestion charging zone: colour and monochrome. The former are used to give an image of the vehicle in the context of its surroundings while the latter are used solely to provide images for reading number plates. Both cameras operate via a chip, a charged couple device (CCD) and X-wave technology which enables the cameras to see far better in limited light conditions. Initial Electronic Security Systems (IESS) supplied the cameras in a deal worth £8m over five years that also covered installation and maintenance.

There are 400 camera positions throughout the congestion charging zone, of which approx. 180 are on the inner ring road. Up to seven cameras are mounted at each position on 8m poles to enable them to read number plates in bumper-to-bumper traffic. In addition to this, there are mobile patrols within the zone. TfL quotes a 90% success rate for accurately capturing each and every number plate, a figure that rises as the vehicle passes more camera positions.

Professional support service provider, Capita, secured the contract with TfL until 2009 to implement and manage the scheme, worth £280m over this period. Capita are responsible for processing payments and fines and employ subcontractors including Mastek, based in Mumbai, India, who are responsible for much of the IT infrastructure.


All images are then sent to the ANPR via a telecommunications system designed and supplied by COLT Telecommunications and BT RedCARE Vision. This system is based on dedicated DWDM (dense wave division multiplexing) technology which link the central data hub with each of the network cameras over analogue video circuits. By using this system, multiple wavelengths can be transmitted over a single optical fibre, allowing the large amounts of data that are collected to be sent simultaneously to the image processing centre.

The ANPR creates a data block for each recognised number plate showing the time and date that the images were taken. These are then checked against a database to verify payment or eligibility for discounts and exemptions. Around one million images are collected per day, and distilled down to around 10,000 to 12,000 vehicles for which there is no record of payment. These then go on for manual check and then around 5,500 penalty notices are issued every day.


As part of the western extension enforcement infrastructure PIPS Technology was awarded a contract in August 2006 to supply ANPR cameras to Siemens, as part of an infrastructure installation contract awarded by TfL. The contract was worth over $9m to PIPS for the proven Spike+ cameras.

The Spike+ is an integrated ANPR camera and processor combining a dual lens camera (colour and infrared) with a compact processor unit capable of operating 24 hours a day in almost any weather conditions. The system is fully web-enabled and has a variety of data communications options including wireless. The Siemens system uses digital technology, not analogue.


A much cheaper alternative to ANPR is ‘Tag and Beacon’ technology. Tag and Beacon involves cars having an electronic tag on the windscreen, which emits radio signals when it passes a roadside beacon, automatically paying the congestion charge. From February to August 2006 TfL trialled this on a small part of the congestion charge system.

The six-month trial involved 500 buses, vans and council vehicles with tags. It also required the installation of 19 gantries in South London between Southwark Bridge and Tower Bridge. The gantries contained the beacons which detect the tags and also cameras to catch those who failed to pay. Results indicated the technology worked well and TfL hopes to introduce it across Central London in 2009, when it renews the contract for running the congestion charge.

Controversially the cost of running the ANPR system is thought to be many times more than that of a similar sized Tag and Beacon system. Gordon Taylor, Chairman of the West London Residents Association (WLRA) (who is highly critical of the congestion charge) commented that “The cost of running the camera system (in London) is nearly 50 times that of the tag and beacon system in Singapore, which is dealing with more or less the same number of vehicles.”
“The ANPR camera system is expected to be out of date by 2009 and will have wasted over £166m of London tax payers’ money.”

The ANPR camera system is expected to be out of date by 2009 and will have wasted, according to several politicians such as Hammersmith and Fulham MP Greg Hands and London Assembly Conservative member Angie Bray, over £166m of London tax payers’ money. To introduce Tag and Beacon will require a complete reinstallation (wiring) of the system.

Another moot fact is the Tag and Beacon system would significantly cut down the number of fines levied for non-payment, as payments are carried out automatically – the majority of fines are levied on those who forget to pay. This would mean a reduction in the revenue stream.


A Permanent Evidence Store repository (PES), provided by TOWER Technology, holds the number plate images collected from vehicles that have driven inside the central London Congestion Charging zone during charging hours. All images that match the information held on the database are discarded. For those who have not paid the charge, images are sent to the WORM drive (Write Once Read Many).

Each image is encrypted and digitally signed at the first point of capture to prevent any modification to the original image. Images of number plates belonging to those who have not paid to register by midnight are then manually checked against DVLA databases for a penalty notice to be issued. The system will store vast amounts of data (up to several terabytes) comprised mainly of number plate images. Of course those who have paid the charge and not entered London for one reason or another are not reimbursed.

PUBLICATION: Road Traffic Technology