Congestion on core road networks is a major problem for many countries around the world. Indeed, according to the largest ever study of global traffic, conducted by INRIX in 2017, congestion in the US alone costs $305 billion (€257 billion). In the UK, Highways England estimates the cost of congestion on the motorway and major road network to be in the region of £2 billion (€2 billion) every year.
As Chris Shannon, CEO of Fotech Solutions says, the economic burden of congestion means that many countries are now trialling the concept of ‘smart motorways’. The first test of a smart motorway project took place in 2006 in the UK, and since then the concept has attracted a lot of interest with schemes becoming common in several countries, including Australia, New Zealand and Switzerland.
‘Smart motorways’ actually comprise several different variants. Regardless of these nuances though, the most common and visible features of a smart motorway include some use of the hard shoulder as a traffic lane and variable speed limits. These measures are intended to increase road capacity and to keep traffic flowing as smoothly as possible.
‘Improvements to be made’
Evidence from the UK, which currently has the most deployments, suggests that there are still improvements in the technologies that underpin smart motorways to be made.
While data shows that smart motorways have increased capacity by up to a third, a recent report published by the UK’s Department for Transport (DfT) highlights that although smart motorways carried 10.7% of motorway traffic in the period 2015-18 (inclusive) they accounted for, on average, 11.4% of the serious casualties.
As such, smart motorways are a potentially powerful solution to the issue of congestion, but if their use is to be expanded we have to ensure that the risk to drivers is minimised. If anything, smart motorways should be safer than the normal road network.
If this is to be achieved, then we need to take a look at the fundamental technology that underpins smart motorway initiatives.
The limitations of smart motorways
The key technical issue for smart motorways is the reliance on cameras and induction loops. Typically loops or cameras are installed every 400 metres along a smart motorway. Clearly, these ‘point’ sensors cannot deliver full continuous monitoring of the entire motorway.
There are inherently gaps in the coverage and these gaps are where delays and errors creep in, which in turn increase the risks for drivers. For example, the DfT report highlighted that the camera-based system used to identify broken down vehicles or drivers experiencing issues still takes an average of 17 minutes to spot a vehicle in trouble.
It then takes a further 17 minutes for a rescue team to arrive on the scene. If a driver is in trouble on a fast-moving motorway, a half hour response time is very obviously a significant risk.
Unfortunately, installing sensors at more regular intervals is very costly and so there will always be compromises in the coverage point sensors can provide. But how can we use technology to improve performance and in particular speed up incident detection times?
Using fibre networks as additional sensors
There is potentially a solution already in the ground. The sensor networks for smart motorways are already connected via fibre cables and this fibre could be put to use as a sensor in its own right. For fibre owners and installers there is a significant opportunity to offer more value to smart motorway schemes.
Wherever fibre is installed alongside a motorway, the addition of Distributed Acoustic Sensor (DAS) technology can effectively convert the cable into thousands of vibration sensors as if you are deploying an army of microphones along the roadway.
These vibration sensors can detect the unique ‘acoustic signature’ of a range of disturbances in the road disruptions in the flow of traffic or changing behaviour in the vehicles (i.e. slowing down/speeding up/changing lanes) and inform operators on what incidents have taken place, exactly where it happened and when it happened.
By virtue of being fibre-based, this system inherently provides full coverage of the entire length of the motorway ‘filling in’ the gaps between cameras and loops to increase the efficacy and accuracy of identifying incidents.
Fibre sensors also provide automated alerts in real-time boosting response times. This is crucial to minimising the potential disruption to keep traffic flowing even more smoothly and minimising risks to drivers.
While smart motorways remain in their infancy, it is clear that they are an appealing solution to the challenge of congestion. However, safety of the road users must be paramount. While existing sensors provide a certain level of performance, we must explore every possible technology that can make systems more effective and minimise risk. Fibre infrastructure has a massive role to play in delivering on this challenge.
The author is Chris Shannon, CEO, Fotech Solutions.