Cities of the future

As mobility evolves to reflect changes in technology, attitudes, policy and the environment, bitumen is at the heart of this changing ecosystem as road infrastructure becomes increasingly ‘smarter’.

What smart road infrastructure in cities of the future might look like and be able to do, in terms of mobility and connectivity, was one of the key topics debated in Berlin at the recent E&E Event 2018, ‘Preparing the asphalt industry for the future’.

Another important issue relating to cities of the future discussed in Berlin was the increased focus upon sustainability and ways to reduce the environmental footprint and impact of asphalt roads. The Sustainability session explored a number of areas including the role different asphalt mixes can and need to play in reducing CO₂ emissions, increasing recycling and cutting rolling resistance (requiring less fuel consumption) without compromising skid resistance and safety.

Particularly within the context of cities, a significant development in how mobility is evolving is the exponential growth in car-sharing, which is predicted to grow to 15.6 million users¹ in Europe in 2020 – from just 0.7 million in 2012. Again within the urban setting, there is much work being done to better integrate public transport systems in order to try to reduce the numbers of cars being driven into a city so that the drivers can enjoy the level of mobility that they desire.

However, despite all the policy initiatives aimed at reducing the volume of vehicles on our roads – such as better-integrated transport systems, the phenomenal growth in car-pooling/sharing, office buses and cycle highways - the total number of private and commercial vehicles in use across Europe has risen by 5% over the past five years and now exceeds 378 million².

¹Monitor Deloitte, Car-sharing in Europe, June 2017
²ACEA Report - Vehicles in use Europe 2017

Improving road utilisation

Unsurprisingly, investigating potential ways to increase the efficiency of existing road networks is a key area of research.

High-profile trials of driverless cars in cities have attracted much debate, while recent tests of 10-15 long lorry convoys on intra-urban roads in the Netherlands generated some interesting results and posed specific challenges for the bitumen and asphalt industry.

Namely producing an asphalt pavement which can cope with longer periods of heavy weights on the right-hand carriageway without the road surface having adequate time to ‘recover’ between lorries - and also taking into account climate change with rising temperatures which both could lead to an increased risk of accelerated rutting on heavy duty lanes.

Road technology innovation

There is a lot of innovative research and development work being undertaken by and on behalf of the bitumen and asphalt industries, exploring the wider role that asphalt roads could play within the smarter cities of the future.

Harnessing energy from the sun

Sustainability – A successful trial in France demonstrated the effectiveness of imbedding solar panels into the surface of a village road, to provide power for road furniture. This approach could have significant application within cities of the future, to power street lights, for instance. Similar studies have also been undertaken in the United Kingdom and the United States. 

Safety – Again in France, successful trials have taken place into the practicality and effectiveness of building a heat exchanger into the body of a road to capture heat from the road surface, so that it can subsequently be used to warm the road surface when the temperature drops in cold weather. A similar concept is also currently being developed for use in particularly hot conditions, where the asphalt mix is refined in order to produce a road surface that promotes cooling.

Safety and Sustainability – the bitumen and asphalt industries have also developed binders with luminescent and / or phosphorescent properties, which when introduced into the asphalt mix reduce the need for road lighting and can also contribute to improved road safety. These types of materials are also now beginning to be used in Poland and the Netherlands for example, to create glow in the dark cycle paths, where the path is illuminated at night when it ‘releases’ energy it has captured and stored from the sun during the day.

Developments in the asphalt mix

Safety – by modifying the asphalt mix, it is possible to make the road surface change colour according to variations in the ambient temperature. This safety feature can provide drivers with a visual representation of when the road surface is cold, and therefore when there is likely to be a greater risk of their vehicle skidding.

Safety and Connectivity – on a similar tack, there has also been research into the incorporation of sensors into the asphalt mix, facilitating communication with the vehicle/driver regarding the road temperature and grip.

Noise – while noise-reducing road surfaces have been used on motorways for some time, there have also been trials in Germany and Paris, where asphalt mixtures with different additives have been laid with the aim of creating quieter road surfaces within an urban setting.

Drainage – for roads where there is a high risk of flooding, or on heavily-trafficked roads where surface water can present a major safety hazard, research work is ongoing regarding ways to increase the porosity of the road surface. In Paris this summer 2018, there will be a trial of a new porous road surface.

Carbon footprint – a huge amount of work has been undertaken, and more is ongoing, looking at ways to minimise the impact on the environment of asphalt roads. Much of this was addressed in the recent feature article entitled ‘Driving on asphalt roads takes less energy’ published on this website.

What place for bitumen in cities of the future?

While we cannot say for sure now what the exact roles are that bitumen will play in cities of the future, we do know that because of all the ongoing research and development that is being undertaken, bitumen - as a core component of road pavement asphalt - will have a key role to play.