
You know that feeling when you drive towards a green light and it turns red a few metres before you get there? Frustrating, isn’t it. Think also about the extra fuel you use accelerating to ‘beat’ the light or waste when you slam on the brakes – it’s, well …. a waste!
In our towns and city centres, this scenario seems to be the norm rather than the exception. However, imagine if when you got a green light you could cruise along and know all the lights will turn green as you arrive.
Whilst some councils have implemented this scenario on a small-scale, these ‘green waves’ have the potential to become a widespread reality.
Current logic
The reason for the current situation is the way our traffic signals are optimised. Minimising delay is the ultimate goal with traffic jams (congestion) to be avoided at all costs. At the moment, current thinking is that if vehicles stop at every light on their journey, but sit in less traffic, that is good. The rationale behind this is based on average speed models, which assume that reducing journey time uses less fuel, because it calculates that average speed multiplied by engine running time equals petrol consumption. However, this is not actually the case.
Working with Aardvark EM Limited, Hydrock is looking at things differently.
Applying a new logic
The National Planning Policy Framework notes that sustainability has three strands – social, economic and environmental. Whilst queuing and delay remain key considerations in how we manage our roads, other factors can carry equal or greater weight – including air quality.
Take a 4km journey in a 1384kg vehicle (the EU average), moving through seven sets of traffic lights. If the car stops at every light and waits for 10 seconds it will use 2.3kWh of energy (the equivalent of 23 hours of watching TV).
If that same car drove the trip without stopping and starting it would use around 1.25 kWh – nearly half the energy. If it doesn’t have to stop on the journey, the car could sit at the first set of traffic lights for ten minutes, engine running, and still consume the same energy as the car stopping and starting.
This huge energy difference is achieved because idling vehicle fuel consumption is a fraction of consumption during acceleration, and lower than consumption when cruising.
Could a rethink of our approach to traffic lights, focusing on eliminating wasteful stops and starts, be in order?
Modelling a new approach
Hydrock is working with Aardvark and a local university to prepare a city-wide detailed (microsimulation) model. Our VISSIM microsimulation modelling tools can simulate individual vehicles down to each gear change, and even model aggression profiles of drivers.
Our work will test the operation of the highway network as it currently is, as well as networks which are optimised in the interests of queuing / delay (the standard approach) and air quality.
Changing behaviours
‘Green waves’ require some compromise. As a driver, you are likely to sit at a light for a bit longer, whilst others are ‘getting all the green lights’.
But, think of it as rolling all your stationary time for a journey into one, so overall journey times are not dramatically affected. Ten minutes is an extreme example, but provided people know why they are waiting, once that first red light turns green, they would not have to stop – as long as they stick to the speed limit. It’s a bit like taking a plane – arrive, wait and then go.
Knock-on benefits
The energy saving potential is huge. As well as this, non-exhaust emissions, which are particles from the wear and tear of car tyres, brakes, engines and the roads we drive on, would be slashed. These are estimated by the National Atmospheric Emissions Inventory (NAEI) to contribute to over half of all Particulate Matter emissions in the country.
Reducing these would also reduce vehicle and road wear and tear, meaning lower car servicing bills on top of the fuel savings and less road maintenance.
This research project is just one example of how Hydrock and its partners are engaging with the opportunities and challenges of future transport across disciplines that include air quality, noise, carbon accounting, transport planning, transport modelling, and transport policy.
For more information check out our specialist Air Quality and Transportation services.
Explore related
- Articles

NHS Trusts need to be ‘fund-ready’ to maximise Government’s decarbonisation support
Read more- Articles

The Building Safety Act: Is the building industry sleepwalking into a new regulatory regime?
Read more- Articles

Interview: Ric Hampton appointed to Bristol Nights Advisory Board to support nightlife & culture
Read more- News

Building with Nature accreditation emphasises importance of green and blue infrastructure
Read more- News

Hydrock ranks #2 nationally and #1 regionally in three Best Companies 2023 league tables!
Read more- Articles

Hydrock comments in Building: The Building Safety Act and what the second staircase rule would mean for high-rise blocks
Read more- Articles

Hydrock roundtable: Diversity and access to careers in the built environment sector
Read more- News

Hydrock joins Task Group for delivery of UK’s first Net Zero Carbon Buildings Standard
Read more- Articles

Hydrock comments in Building: Strong and stable? This government is anything but when it comes to energy infrastructure
Read more- News

Hydrock adds leading technical specialist to its civil and structural team in Yorkshire
Read more- News

Zuzanna Bialkowska awarded ‘Up-and-Coming Fire Engineer’ of the year by The Society of Fire Protection Engineers
Read more- News

Hydrock shortlisted for Engineering Consultant of the Year at the Building Awards 2022
Read more- News

Hydrock appointed to deliver catheterisation scanner suite at St Bartholomew’s Hospital
Read more- Articles

Hydrock comments in New Civil Engineer: The cost of blindly installing EV charge points
Read more- News

Extreme heat: how UK buildings and infrastructure are dangerously ill-equipped to cope
Read more- News

Simon Cole joins Hydrock as leading technical specialist for Geo-Environmental and Geotechnical division
Read more- News

Hydrock launches carbon verification and validation service to help address climate change
Read more- News

Hydrock selected for specialist public sector consultancy framework in the North East
Read more- News

Hydrock engineer Chris Jones featured in Building Magazine covering how data centres can help save energy
Read more- News

Hydrock's Acoustics division joins industry-recognised Association of Noise Consultants
Read more- News

Hydrock engineer Chris Jones covers ‘risk versus reward in data centres’ for Property EU
Read more- News

Hydrock nets geo-environmental and geo-technical role on multi-million-pound Belle Vue Academy site
Read more- News

Hydrock support successful planning application to extend Western Community Hospital in Southampton
Read more- News

Hydrock’s Civil & Structural engineering team appointed on next stages of £104m Patchworks development
Read more- News

Hydrock supports feasibility and planning application on Grade II listed buildings in Leeds
Read more- News

Shortlisted for Consultancy of the year at the Insider Wales Property Awards for second year running
Read more- News

Fire Risk Management team secure industry-recognised fire risk assessment accreditation
Read more- News

Hydrock’s Glen Irwin confirmed on newly launched NABERS UK Independent Design Review Panel
Read more- News

Hydrock celebrates seventh consecutive year in UK’s 100 Best Large Companies to Work For
Read more- News

Hydrock & KTA logistics specialists advise on 1m sq ft reserved matters application at Magna Park North
Read more- News
