Concrete solution to decarbonising transport

Concrete infrastructure will help the government deliver its decarbonising transport plans by increasing the use of public transport, reducing the fuel emissions of vehicles and providing a future infrastructure network that can readily charge electric vehicles as they pass over the road’s surface.

A preface report to the transport plans, due to be announced in the Autumn, has been published by the Department for Transport. The report, ‘Decarbonising Transport: Setting the Challenge’, underlines that transport is the largest contributor to greenhouse gas emissions in the UK contributing 28% of UK domestic CO2 emissions and outlines six strategic priorities to enable the UK to reach net zero CO2 emissions by 2050. These include increasing the use of public transport, decarbonising road vehicles and forwarding the UK as a hub for green transport technology.

Joe Quirke, Chairman of the infrastructure trade association Britpave said: “The Decarbonising Transport report highlights that 58% of car journeys taken in 2018 were for a distance of under five miles. Many of these could be done by the provision of more reliable and punctual public transport. For this, the government should encourage greater investment in busway networks.”

Busways typically consist of two 180mm high concrete kerbs set 2600mm apart on a concrete pavement. The kerbs act as both the guide for the bus and physical segregation from other traffic. This segregation removes the problems of traffic congestion, obstruction by parked vehicles and the use of bus lanes by unauthorised vehicles and so provides for a more reliable and faster bus journey.

“The success of busways speak for themselves,” said Quirke. “Last year, the Leigh to Ellenbrook busway carried over three million passenger journeys. It is estimated that use of the busway has resulted in 580,000 fewer car journeys. The Cambridge to Huntingdon busway is annually carrying nearly 4 million passenger journeys. This is good news in terms of reducing car journeys and so reducing CO2 emissions from road transport.”

Transport CO2 emissions can also be reduced thanks to the stiffer long-term performance of concrete road surfaces. “Concrete roads are stiffer than asphalt and so have less ‘play’ when vehicles

tyre roll over them. This means less rolling resistance resulting in more efficient fuel consumption,” explained Quirke. “These fuel savings can be particularly significant for heavy good vehicles.”

The increased fuel efficiency resulting from driving on concrete roads has been proven by several research studies. Research carried out the Canadian National Research Council’s Centre for Surface Transportation Technology, the Swedish Road and Transport Research Institute and the Nippon Expressway Research Institute have all found that found that vehicles use less fuel when travelling on a concrete road compared to an asphalt pavement.

The government’s decarbonising transport plans focus strongly on the widespread adoption of electric vehicles (EVs). However, the lack of a battery-charging infrastructure could severely hamper their uptake. According to the data company Emu Analytics there are only 16,500 charging points in the whole of the UK. It is estimated that with one million new EVs on UK roads within the next two years there needs to be a network of 100,000 charging points. Currently, only 3 per cent of supermarkets have a charging point. Rapid chargers, which can fill 85 per cent of an EV’s battery in half-an-hour are particularly scarce. The potential problem of a lack of charging points is compounded by the fact that whilst many EV drivers are likely to choose to charge their vehicles at home, or at their workplace, 20 to 30% of motorists do not have off-street parking. More than a third of households in England do not have access to off-street parking, and this proportion increases in most urban areas.

“A new approach to charging points is required. The potential of concrete ‘eRoads’ that inductively charge EVs as they travel should be examined,” said Quirke.

Inductive charging is where the EV battery is charged without the need to plug the vehicle into a charging point. The process is wireless and can be done whilst the EV is on the move or stationary. If the vehicle is moving the process is referred to ‘dynamic charging’.

Quirke points to a number of concrete eRoad options that are being researched and developed where electric coils are installed within the road surface to create a magnetic field. The magnetic field creates an electric current in a secondary coil placed on the vehicle’s undercarriage which feeds the charge to the vehicle’s batteries.

“What is being underlined by the research is the need for the road surface to have long-term durability and minimum maintenance. Both are inherent characteristics of concrete roads,” said Quirke. He added: “A further benefit of concrete roads for the installation wireless modules is that in hot summer temperatures they, unlike asphalt, do not melt. Such melting could dislodge and compromise the positioned embedded wireless system.”

Other exciting possibilities include making the actual concrete road itself conductive. Australian-based Talga Resources are mixing graphene into concrete to make it conductive and so charge an EV whilst it is driving. In Germany, Magment concrete is being developed. This consists of 87 per cent magnetisable aggregates which is waste product from the manufacture of ceramic ferrites and the recycling of electronic scrap. It allows energy to flow into a coil to inductivity charge vehicles as they pass. The proposal is to cast (either precast or insitu) concrete ready-to-connect coil modules that contain all the required wiring including optional sensors for integration into road construction.

“Durability and minimum maintenance are key for future eRoads. This is especially so as the vehicles, particular heavy goods vehicles, will be travelling on the same path in order to charge. The road surface must, therefore, not prematurely deflect or rut. Concrete roads have a performance life of 50-60 years and are so fully able to provide the required long-term durability,” said Quirke.

He concluded: “It is ironic that concrete, often seen as being an environmental problem, could, in fact, be the environmental solution to providing a transport infrastructure that can significantly forward the decarbonising transport agenda.”