Sustainability difficulty

Carl Fergusson, Business Manager for Colas UK, explains why highway engineers working for UK local government are faced with a problem relating to the fundamentals of how they work.

Two forces drive the efforts of highway engineers working for UK local authorities: government policy and the laws of mathematics that they use to better their environment. Usually, educated and socially aware engineers will continually strive to design highway developments in accordance with policies, to build or maintain something that is safer, more economic or more sustainable for the environment.

The rub of the problem however, in UK local government at least, is that there is currently very little definitive guidance for highway engineers wanting to work towards this last and strengthening policy. Whether the projections relating to climate change are believed or not, the growing importance of sustainability policy cannot be denied and local authority engineers need to know how to meet it.

Sustainability is high on the agenda, but it is difficult to define and quantify in the highways sector and engineers need numbers to meet policy requirements. Part of the problem is a lack of consistent direction from central and local government on what parameters engineers should include in their calculations. There are three pillars of sustainability – social, economic and environmental – and every local authority is likely to weigh them differently in terms of importance. For instance, social impacts such as lorry movements, dust and noise are being considered, but what about the long-term economic and environmental implications of different road maintenance and construction methods?

These effects are not being measured (not consistently, anyway) and as a result there is a decoupling of the government’s sustainability policy from what is happening at the local level. Government has set a 60 percent reduction in carbon emissions as its main target, but the social pillar is most important for local authorities wanting to keep local people happy. Local governments can quantify complaints and bad press; measuring the environmental impact of their work is more difficult.

Authorities have been set volume-related recycling targets and reuse of road pavement materials is popular because its benefits, including reduced lorry movements, are immediately apparent. But is it the most sustainable method every time? Probably not, but it is difficult for engineers to make a fully informed evaluation. In some cases, a premium design based around durability could be the most sustainable because it will result in the least social and environmental impact in the long-term. Projects and locations have to be fully evaluated on a case-by-case basis, taking into account all factors, to find out.

Suppliers need direction on policy as well, otherwise how can they direct their efforts in R&D and produce the innovation clients want? We at Colas have a number of road surfacing products and techniques designed to be more sustainable than the conventional. These include our proven Retread and Repave processes – cold and hot mix respectively, and both using in situ recycling to extend the life of pavement surfaces. We have also introduced Vegecol, a non hydrocarbon alternative to bitumen binders that has been used extensively in France.

Plus, our French parent company Colas SA has developed an ‘environmental calculator’: computer software we are now using to evaluate the green credentials of different road surfacing and reconstruction methods in the UK. The many variables of any given project are entered into the software, which then gives values on energy used and greenhouse gas emissions, including CO2. This is a good start towards full evaluation of the sustainability of different methods and local authorities are showing great interest in the case studies we have produced so far. The most sustainable processes in the short-term are those that recycle pavement in situ with cold mix processes involving very little transportation of materials. However, there are many different processes available and some produce other great advantages in saved costs and time.

The subject and issues of sustainability in the highways sector are complex, and what is now really needed from central and local government is clear direction with respect to sustainability. There are pockets of excellence in the UK, but without full evaluation and standards, progress towards Government’s sustainability targets will remain slow.