thumb|300px|ERP gantry along the [[Bukit Timah Expressway.]]
The Electronic Road Pricing (ERP) system is an electronic toll collection scheme adopted in Singapore to manage traffic by way of road pricing, and as a usage-based taxation mechanism to complement the purchase-based Certificate of Entitlement system. There are a total of 93 ERP gantries located throughout the country, along expressways and roads leading towards the Central Area. As of March 2026, only 22 ERP gantries are in operation and are all in expressways where congestion continues to be severe.
The ERP was implemented by the Land Transport Authority (LTA) on 1 April 1998 to replace the preceding Singapore Area Licensing Scheme (ALS) that was first introduced on 11 August 1974 after successfully stress-testing the system with vehicles running at high speed. The system uses open road tolling; vehicles do not stop or slow down to pay tolls.
Singapore was the first city in the world to implement an electronic road toll collection system for purposes of congestion pricing. Its use has inspired other cities around the world in adopting a similar system, particularly London's congestion charge zone (CCZ), Stockholm's congestion tax, With the new system, the ERP scheme will move towards a distance based charging policy, instead of the current system, where a fixed toll is charged when vehicles pass through a physical ERP gantry.
It is anticipated that there will no longer be any need for physical ERP gantries when the system is fully implemented and activated. After all the vehicles are installed with the new OBU, existing ERP gantries will be removed with new visual markers or signs to indicate ERP charging locations.
thumb|320x320px|An On-Board Unit installed on the side of a private motorcycle
Current IU systems will be replaced by onboard units (OBUs) with one-piece units for motorcycles and three-piece units for other vehicles, due to the fact that the current IU system is not operable with the SimplyGo card system that was being introduced in 2017.
Co-developed by NCS Group and MHI Engine System, the Onboard Unit (OBU) will be rolled out in phases and the installation is slated to be completed by 2025. The OBU consists of three components for all vehicles, except for motorcycles, which will remain a one-piece unit.
The three-piece units consists of an antenna, processing unit and a touchscreen display. The antenna and touchscreen display will be affixed on the lower right corner of the front windscreen within sight of the driver, while the processing unit is located on the right side of the passenger side footwell for the three-piece unit.
The OBU is expected to have various features, including being able to display real-time traffic information, and facilitate couponless parking and automatic payment.
Vehicle owners can choose to not install the touchscreen display, but will be unable to adjust the volume of the OBU. Other features such as a future payment system that will be introduced to the OBU, live traffic data and updates, can be accessed via smartphone applications developed with software development kits released by LTA.
LTA announced that the distance-based charging policy will not be implemented in the near future, with no concrete date on when the new policy will take place. The current ERP charges will remain the same, with the OBUs able to work the same as the IUs when passing through a physical ERP gantry. After about one and a half year, more than half a million vehicles had been installed by June 2025. About 5,400 cars, almost two per cent of around 300,000 cars installed with OBU, had problems with their installed OBUs.
History
thumb|Night works during the installation of a new ERP gantry at Hillview
ERP 1.0
A lightweight version of the ERP technology has been implemented for use on parking, and is known as the Electronic Parking System (EPS). It has been adopted by several carpark operators and has replaced the use of autopay tickets or parking coupons. These parking systems have also typically switched to charging by the minute.
In an effort to improve the pricing mechanism and to introduce real-time variable pricing, Singapore's Land Transport Authority, together with IBM, ran a pilot from December 2006 to April 2007, with a traffic estimation and prediction tool (TrEPS), which uses historical traffic data and real-time feeds with flow conditions from several sources, to predict the levels of congestion up to an hour in advance. By accurate estimating prevailing and emerging traffic conditions, this technology is expected to allow variable pricing, together with improved overall traffic management, including the provision of information in advance to alert drivers about conditions ahead, and the prices being charged at that moment.
This system integrates with the various LTA's traffic management existing systems, such as the Green Link Determining System (GLIDE), TrafficScan, Expressway Monitoring Advisory System (EMAS), Junction Electronic Eyes (J-Eyes), and the Electronic Road Pricing system. The pilot results were successful, showing overall prediction results above 85 percent of accuracy. Furthermore, when more data was available, during peak hours, average accuracy raised near or above 90 percent from 10 minutes up to 60 minutes predictions in the future.
During 2020, ERP was mostly suspended due to circuit breaker measures in response to the COVID-19 pandemic in Singapore.
In 2021, the LTA stated that the existing ERP system, which was about 22 years old at that time, was "reaching the end of its operational life". Subsequently, a tender was called and in 2016, NCS and MHI Engine System were jointly awarded the contract to install the new ERP 2.0 system for S$556 million, which was less than ST Electronics's bid of S$1.2 billion. It was reported that the rollout of the new ERP system would begin in 2020. Then-Chief Executive of LTA stated at the time that the NCS-MHI bid "came within our budget" and was superior to ST Electronics', and he was confident that NCS-MHI would be able to "execute the project in a commercially-viable way" notwithstanding the large difference between the bids.
It was also reported that as a result of the COVID-19 pandemic in Singapore in 2020, the fitting of the new OBUs would be delayed to the second half of 2021, with the new ERP system expected to become operational in mid 2023.
In November 2021, the deployment was delayed again to the second half of 2023 due to a global shortage of microchips for the OBUs. Then-Deputy Prime Minister Heng Swee Keat also stated that the technology required for distance-based charging "is still several years away". All vehicles are expected to be fitted with the new on-board units by the end of 2025 but the system will not be turned on until further notice. In response, the LTA stated that it would make changes to the system to allow drivers to temporarily deactivate their CEPAS card using the touchscreen without having to remove the card physically. The LTA also stated that it would allow drivers to decide where to install the card reader component, subject to space constraints in the relevant vehicle and technical feasibility.
As of April 2024, more than 13,000 vehicles had been fitted with the new OBUs, of which about 75% were company vehicles, such as buses and motorcycles.
Impact
A study on the long-term effects of congestion pricing in Singapore claimed that "traffic congestion had not been eliminated—it had merely been shifted in time and location" and that the average travel time has increased.
In contrast, another report stated that road traffic decreased by nearly 25,000 vehicles during peak hours, with average road speeds increasing by about 20%. Within the restricted zone itself, traffic has gone down by about 13% during ERP operational hours, with vehicle numbers dropping from 270,000 to 235,000. It has been observed that car-pooling and public transport has increased, while the hours of peak vehicular traffic has also gradually eased and spread into off-peak hours, suggesting a more productive use of road space. In addition, it has been noted that average road speeds for expressways and major roads remained the same, despite rising traffic volumes over the years.
In some cases, the implementation of an ERP gantry along a road may move the traffic to outer roads or shift would-be car users towards public transport. One instance of this is that the ERP gantries have been said to have caused traffic to increase substantially in the arterial roads. In response, congestion on the East Coast Parkway was relieved with the opening of Marina Coastal Expressway on 29 December 2013. The rising traffic has prompted the LTA to encourage more Singaporeans to switch to public transport as part of the country's general "car-lite society" plan, by building more MRT train lines and introducing more bus services. The full completion of the Downtown MRT line on 21 October 2017 complements the Pan Island Expressway. The Thomson–East Coast MRT line also runs largely parallel to the Seletar Expressway and East Coast Parkway.
Adoption by other metropolitan areas
In Ontario, Canada, an electronic road pricing system is used on Highway 407 to collect tolls electronically and billed to the owner of the car by taking a picture of its license plate.
The ERP system attracted the attention of transport planners and managers in other metropolitan areas, particularly those in Europe and the United States. For example, the London congestion charge was introduced on 17 February 2003, after London officials visited Singapore to study the ERP system, and used it as a reference for the London system. London's charge area was expanded in 2007.
The Stockholm congestion tax is also a congestion pricing system implemented as a tax which is levied on most vehicles entering and exiting central Stockholm, Sweden. The congestion tax was implemented on a permanent basis on 1 August 2007, after a seven-month trial period was held between 3 January 2006 and 31 July 2006.
In 2007, Dubai, in the United Arab Emirates, implemented a corridor congestion pricing scheme called Salik which works on similar principles. In January 2008, Milan introduced a traffic charge scheme as a one-year trial, called Ecopass, and exempts high emission standard vehicles and some alternate fuel vehicles. This tax was substituted in 2012 by the Area C system, which places a charge on nearly all vehicles entering the city centre during weekdays.
A similar system is expected to be operational on selected roads in Jakarta, the capital of Indonesia by early 2019.
Payment modes
{| class="wikitable"
! rowspan="2" |Payment
! colspan="3" |Acceptance
! rowspan="2" |Authorised sources
! rowspan="2" |Notes
|-
!1st Gen IU
!2nd Gen IU
!OBU