Real-world traffic emissions characterization

The main purpose of the RSD is to measure the reality in order to make decisions based on data. What is not measured, cannot be improved. The first step in almost any large-scale program is to analyze the traffic data collected at all different points in the city, which leads to many other potential applications.

The objective

This application is related to large-scale data acquisition to try to answer several critical questions, such as:

  • How much pollution is produced by road transport in a specific city?
  • How much does each group of vehicles contribute to total pollution?
  • How do the actual emissions from vehicles in my city compare to other similar cities?
  • What is the relationship between actual vehicle emissions and the different areas of my city?
  • How often do hybrid vehicles run in electric mode in each area of my city?
  • How do my current emission inventories compare to actual emissions from the fleet in circulation?

How is it done?

Monitoring real-driving emissions in MANY different locations, to create a “map” of real-world traffic emissions. Because of this, we mainly use portable RSDs to deploy them on different roads and streets every few days.


As data is collected, we analyze traffic emissions by different parameters:

  • Urban parameters: city district, specific site, road slope, road type, traffic intensity, etc.
  • Vehicle parameters: fuel type, vehicle type, vehicle age, Euro Standard, weight, brand, model, etc.
  • Traffic parameters: traffic intensity, time slot of the day, nearby traffic incidents, etc.

Some success stories

We have been doing road traffic characterizations in many cities around the world for many years. Here are some of the most relevant examples:

Zurich 2002-2020

AWEL, a governmental agency of the Canton of Zürich, Switzerland, has been using Opus Remote Sensing Devices for 18 years, to study the real-world emissions from motor vehicles in Zurich. Their constant work represents the best continuous evaluation of road traffic emissions in Europe. AWEL began using RSD systems with close support from Opus, but soon had complete autonomy to use them independently. In this way, AWEL rents the equipment when needed with greater flexibility. This type of collaboration is now replicated with other international partners.

The methodology employed by AWEL is unique. Every year they place the Opus RSDs in the same road, for a period of about 4 to 6 months. Only 2 locations have been used. As the emissions from motor vehicles driving in one location are different from those in another, this methodology allows the geographic variability to be eliminated. This way of assessing emissions over time allows for the identification of market trends, checking whether the emissions from vehicles are reducing year by year as they should.

Colorado and Virginia 2010-2018

For a long time, Opus Inspection has used remote sensing to screen the cleanest and dirtiest vehicles circulating in the states of Colorado and Virginia (see our high-emitter programs). This activity, focused on the improvement of vehicle inspection programs, has allowed the collection of hundreds of millions of very valuable records.


The ICCT has compiled 60 million remote sensing emissions records from US Opus Inspection and the University of Denver to investigate the emissions of U.S. cars and trucks.

Learn more about this study with the following ICCT video:

Access ICCT publications here:

Madrid 2017-2020

Opus RSE has been monitoring the actual emissions of the Madrid fleet for almost 15 years. The last major program began in 2017. In this last period more than 1 million records have already been collected in dozens of different points in the urban area of Madrid.

This massive characterization of real road traffic emissions has yielded incredible results up to now:

Evaluation of real-world traffic emissions by vehicle groups (car type, make and model, year of registration, fuel, city area, etc.).

Analysis of the emissions of the new Euro 6 cars as the regulation has been introduced in the market.

Analysis of the real-world emissions according to the Spanish Envormental Labelling System.

Analysis of the actual emissions from the hybrids and when and where the PHEVs are circulating in electric mode in the city.

Analysis of real market trends, by identifying which vehicles actually circulate each year.

Information campaigns to citizens and information to drivers of the real emissions of their vehickes with information panels.

Individual communications to drivers through mobile applications and to connected cars. Notification in real-time.

Definition of an identification methodology and emission limits for high-emitters customized for Madrid.

Installation of a new fixed traffic emission measurement cabin to extend real-world traffic emissions monitoring.

London 2017-2018

Along with the FIA Foundation, Global NCAP, Emissions Analytics, Transport and Environment and the C40 Cities, the International Council on Clean Transportation (ICCT) has established The Real Urban Emissions Initiative (TRUE). The TRUE initiative seeks to supply cities with data regarding the real-world emissions of their car fleets and equip them with technical information that can be used for strategic decision-making. Following this objective, the ICCT decided to contract Opus RSE to conduct on-road remote sensing measurements from light-duty vehicles in London. Opus partnered with Ricardo Energy & Environment and the University of York to carry on this project.

You can learn more and read the project reports prepared by the ICCT in the following links:

Krakow 2019

In June 2019 Opus conducted the first remote sensing project in Poland.  144,000 vehicles were measured in 14 days. Opus RSE partnered with polish local company TurboSpec to carry out the project. The reults have helped the authorities to find out some incredible facts about the city's private and public circulating fleet.

The project had to start 10 days after granting the project to Opus and Turbospec. Together we had to do the project planning, prepare the delivery of the equipment, secure the permits for measuring and other project preparations in a record time. The project was executed on time, with no delay and incredible results. The measurements were also done during an extreme heatwave and with some heavy rainy days. The Remote Sensing Devices were placed at 10 different locations in Krakow. This mobility can only be achieved with Opus portable RSDs.

In 2020 the ICCT conducted an independent study of the data collected during the project:

Warsaw 2020

After the success of the project in Krakow in 2019, the city of Warsaw decided to carry out another study to characterize the emissions of its circulating fleet in 2020. This project is part of the TRUE initiative, led by the ICCT, which subcontracted Opus and Turbospec. The project has been a complete success, having obtained 230,000 records in just 14 days.

Brussels 2020

In parallel to the characterization carried out in Warsaw, the ICCT subcontracted Opus to carry out another similar project in Brussels. In this case Opus partnered with Turbospec, an expert in traffic and enforcement in Belgium.

This project is even more ambitious and complicated. Measurements had to be taken in the middle of the Covid-19 pandemic, including a devastating second wave in the country while measurements were being taken, which was associated with severe mobility restrictions in the city.

In addition to measuring the emissions of the city's vehicles, Bruxelles Environment is also measuring the noise of vehicles as they pass by, in order to correlate these measurements with actual emissions. That study may result in a new understanding of the relationship between these two modes of pollution. The consortium is also working with inspection bodies to study how remote RSD measurements relate to MOT testing, which could change the way vehicle emissions are controlled nationally. 

Opus RSE

Gaztambide, 45

28015, Madrid (Spain)

Phone: (+34) 91 559 28 68


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