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Fibre optic distributed acoustic sensing technology to improve air quality

Fibre optic distributed acoustic sensing technology to improve air quality
© Fotech

[Fotech] Fibre optic distributed acoustic sensing (DAS) technology from Fotech – a bp Launchpad company – has proven itself in a pioneering UK air quality project, winning a coveted 2021 FOSA Project of the Year award in the process. The aim of The Air Quality Simulation Project, led by Staffordshire County Council, is to improve the air quality at the busy A52 / A520 Cellarhead crossroads. The project required a comprehensive traffic simulation model, which Fotech’s DAS technology was instrumental in creating, using data obtained from fibre optic sensing.

In the UK, air pollution is the top environmental risk to health, as well as being the fourth-greatest overall threat to health after cancer, heart disease and obesity. From an economic standpoint, it is estimated that in the UK, the current cost of poor air quality is between GBP 22.7 billion and GBP 71.1 billion. Reducing emissions and improving air quality will have far-reaching health and economic benefits.

There will be a reduction of Nitrogen Oxide (NOx) and Carbon Dioxide (CO2) emissions thanks to a worldwide trend to move from petrol- and diesel-powered vehicles to electric vehicles (EVs). However, the arguably more serious particulate (PMx) emissions could potentially increase with the growing uptake of EVs because these vehicles are typically heavier and cause more wear and tear to tyres and road surfaces. Keeping these vehicles moving smoothly without unnecessary braking will pay dividends for curbing these often-overlooked emissions.

With this in mind, the Air Quality Simulation Project, was established to look at improving air quality through smart traffic management. The project is part of the SIMULATE Live Lab programme, Air Quality Challenge. With funding from the UK’s Department of Transport, this programme brings together Staffordshire County Council, Keele University, Amey and industry specialists Catapult Connected Places to deliver innovative solutions to combat challenges in air quality.

Discovering DAS
In this project, Fotech’s DAS technology was implemented on approximately 1 km of standard telecommunications fibre in each direction from the Cellarhead crossroads, in order to detect, to classify, to locate and to track vehicles travelling towards the junction. The DAS technology essentially turns the fibre optic cable network into thousands of vibration sensors, able to detect vehicles over several kilometres.

Fibre optic distributed acoustic sensing technology to improve air quality

© Fotech

The technology sends thousands of pulses of light along a cable every second and monitors the fine pattern of light reflected back. When acoustic or vibrational energy – such as that created by a passing vehicle – creates a strain on the optical fibre, this changes the reflected light pattern. By using advanced algorithms and processing techniques, DAS analyses these changes to identify and to categorise the disturbance. Each type of disturbance has its own signature, and the technology can tell an operator in real-time, what happened, exactly where it happened and when it happened.

Machine learning for detailed data
Vital to creating the traffic simulation model were Fotech’s special Machine Learned algorithms, which meant the vehicles were monitored with a very high degree of confidence. Thanks to the algorithms, the technology easily distinguished between different vehicle types such as cars, light- and heavy-duty vehicles, and, by monitoring their movements, anticipated their arrival times at the crossroads.

In the next phase of the project, data from the traffic simulation model will feed into smart traffic control algorithms, which can then be used to schedule the lights in a way that allows deceleration and acceleration to be reduced. This will keep vehicles moving more freely, particularly the heavier polluters, and will cut emissions caused by stop-start traffic.

One of the main benefits of DAS technology is its ability to provide real-time data. This data may be used to make real-time changes to traffic light phasing and improve traffic flow in the wider project.

Implications for the future
The success of this model has much wider implications, however, with DAS becoming central to calculating vehicle emissions, managing traffic flow and reducing congestion.

If future trials of the smart traffic systems in Cellarhead are equally successful, they open up an exciting new application for DAS. It will be the first time that DAS has been used to manage traffic flow to reduce emissions and improve air quality.

It is expected that standard telecommunication fibre optic cables integrated with DAS technology could reduce emissions significantly, creating a positive effect on public health. Indeed, it is anticipated that using fibre optic sensing as a means of smart traffic management will reduce emissions of (NOx, CO2 and PMx) by between 10% and 20%.

There will be an even greater effect on reducing congestion and pollution if this technology can then be installed across junctions in an entire city and local authorities can dynamically change traffic light sequencing in real-time.