Green light optimal speed advisory (GLOSA)

The challenge

In 2019, we ran a competition seeking innovative ideas for developing digital roads and improving air quality.

One winning entry explored technology known as Green Light Optimised Speed Advisory (GLOSA). ​

GLOSA gives drivers speed information that helps them to pass through green traffic lights. This reduces the number of vehicle stop-starts at signalised motorway junctions and can, in turn, improve air quality.​

examples of information that GLOSA displays
GLOSA gives drivers speed information that helps them to pass through green traffic lights

​The project

We worked with Amey to develop and trial the in-vehicle technology. Other partners involved included:​

  • Transport for Greater Manchester (TfGM) – for traffic control systems access​
  • Eastpoint – to develop the GLOSA app​
  • Ricardo – for emissions testing​

​We ran the trial using traffic lights on three slip roads in the north west.

  • the A627(M) Broadway junction
  • the north and southbound roundabout approaches at junction 2 of the M66

We used a portable emission measurement system to capture real driving emissions data on these short routes.

We used two vehicles, a light commercial vehicle and a heavy goods vehicle (HGV), completing around 400 trips for the trial. We generated comparable data by doing a number of runs on the same slip road.

Initial analysis of results suggests that vehicle CO2 emissions were reduced by as much as 27% by minimising unnecessary speed changes.

This also led to a 17% reduction in the level of nitrogen oxide (NOx). The most promising results were from HGV testing.​

​We are now testing the technology with a different type of traffic signal control system. If testing is successful, we will start working on a GLOSA Strategy for potential roll-out in our third road period (RIS3 2025-2030).

Dashboard mounted app
Reducing vehicle stop-starts at signalised motorway junctions can improve air quality

Innovation theme

Connected and autonomous vehicle
Energy and environment

Imperative

Customer