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Since 2017, HEAT has been providing world-class remote-sensing services to Scotland and its municipalities with its EDAR system. EDAR is an innovative solution aiding Scotland in meeting

its air-quality goals as well as bringing its Low Emission Zones (LEZ) to the forefront

by leading the way with the most advanced technology available on the market today.  

In 2023, HEAT continuously monitored vehicle emissions using its proprietary technology, EDAR, in Scotland’s four major cities of Aberdeen, Dundee, Edinburgh, and Glasgow on city roadways in and out of the Low Emission Zones, including trunk roads. The results of Phase II helped inform future air-quality policy and investigated ways to reduce air-pollution levels by mitigating the misuse of emission- abatement equipment and controls. 

The comprehensive turnkey service in 2023 was the Phase II continuation of a three-year commitment to assess the real-world nitrogen oxide (NOx) emissions from all vehicle types, including passenger cars, taxis, and private hires in identified zones prior to the launch of four low-emission zones (LEZs) in the city centers of each of the four major metropolitan areas.

Scotland has the largest collection of remote sensing vehicle-emission records in the United Kingdom and continental Europe, totaling more than 1.5 million valid vehicle emissions records compiled during four months of study over the three-year contract in the country.

“Remote sensing provides insight into real-world emissions of diesel and petrol vehicles in the urban environment, detecting emissions that diverge from the type approval limit and typical levels. In improving our understanding of vehicle emissions and developing effective solutions, we can support the delivery of policies to improve air quality and benefit the health of people in Scotland,” said Derek McCreadie, Air Quality and Environment Senior Advisor of Transport Scotland.

Transport Scotland’s 2022 collaboration with HEAT proved to be the most extensive remote sensing testing campaign in Europe to that point. This first-of-its-kind project collected real-world emissions in Edinburgh, Glasgow, Dundee, and Aberdeen in Scotland over a three-year period to support evidence-based transportation policies at the local and national level. The project, in part, was initiated to support the Scottish Government's commitment to introduce LEZs into the country’s most populated cities. LEZs set an environmental limit on certain road spaces and restrict entry of the most polluting vehicles, with the aim of improving air quality in Scotland’s city centers. Scotland launched LEZs in the cities involved in the study during the summer of 2023.

In Spring 2022, EDAR remote sensing was conducted in all four Scottish cities simultaneously. More than 480,000 real-world emissions were collected during the month of observation. An initial phase of study was conducted in October 2021.

Key findings from the 2022 study include the following:

  • Passenger cars were the most predominant vehicle type, and Euro 6 vehicles accounted for over 30% of all measurements.

  • NOx emissions of diesel vehicles significantly improved after the introduction of the Real Driving Emission (RDE) Euro 6d-TEMP standard, showing an average 60% reduction from the preceding Euro 6 standards.

  • Despite those improvements, post-RDE Euro 6 cars showed variable NOx emissions performance across vehicle families, as only a minority had mean real-world emissions below the RDE type-approval limit.

  • The data provided further evidence of increased NOx and CO emissions from petrol vehicles with higher age and mileage. The results additionally showed that there may be a positive correlation between the ages and NOx emission performance of diesel vehicles, especially for those certified to below Euro 6.

What are Trunk Roads? 

The trunk road, a major asset of Transport Scotland, is a motorway network of 3,507 km (2,179 miles) long that connects Scotland’s major cities, towns, airports, and ports enabling the movement of people, goods, and services. It carries roughly 60% of the country’s heavy-goods vehicles.

In August 2019, HEAT was initially awarded a contract by Transport Scotland to implement Phase I of a remote-sensing LEZ pilot program. The contract called for the collection of 300,000 valid emissions records to be collected on Scotland's trunk roads, with the first installation to be completed by August 31, 2019. HEAT mobilized quickly once awarded the contract at the beginning of August and accomplished this task on time to complete Phase I, Part I, of the program.

“We hope this EDAR pilot scheme will assess the benefits of the technology to help demonstrate to drivers the emissions emitted by their vehicles and make them consider the impact of their actions on the environment.”
-Tom Burr
Vehicle Emissions Partnership

In Phase I, Part II, the agreement required the installation of EDAR systems on gantries overlooking high-speed highways by February 2020 to complete the data collection and meet the goal number of 300,000 valid remote-sensing records from Scotland’s trunk roads. During the data-collection portion of Phase I, Part II, EDAR collected over 75 percent of the required 300,000 records during a three-week period of Scotland’s most challenging winter weather, which ended at the end of February 2020. This program aims to trial the use of remote sensing for policing and monitoring LEZs in Scotland. The measurements from this pilot and the expertise from HEAT’s remote-sensing specialists will support Transport Scotland in the implementation of a full-scale program as part of the country’s air-quality-improvement scheme.


The Vehicle Emissions Partnership (VEP) and the Scottish Government funded a pilot deployment of the EDAR system in Scotland in March 2017 as part of their “Switch Off and Breathe” campaign. Testing took place in three locations, including putting one EDAR system in the Glasgow and Edinburgh areas for more than a month during the winter, exposing EDAR to challenging weather conditions such as snow, rain, and hail. Despite these adverse conditions, EDAR was able to successfully collect emissions data.

A single EDAR system collected 140,000 valid reads during a two-week study, which provided substantial amounts of information for local municipalities to perform fleet analysis and modeling, while increasing public awareness of the effects of on-road emissions. This data also helped contribute to making plans to tackle issues associated with vehicle emissions and to assist in the creation of sound public policy for Low Emission Zones. During this installation, EDAR collected gas data from each vehicle, including CO2, NO, NO2, and PM.


EDAR successfully captured emissions from all vehicle types that traveled underneath the unit, including heavy-duty diesels, and demonstrated its ability to run unmanned, 24/7, under demanding weather conditions, thus further proving that EDAR operates effectively and efficiently in any season.

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