Words by Dr Suzy Charman

The Road Safety Foundation advocates for safe and healthy mobility through the adoption of a Safe System. Part of our recent work has focused on identifying investment packages likely to give high returns and analysing the safety performance of roads over time.

Our work has also been used to support the business case for DfT’s Safer Roads Fund and then carry out surveys, support and model, underpinning the investment of £147.5m on 75 local A roads in England. 

Large-scale investments, particularly on our strategic roads, are primarily motivated by increasing capacity not safety. Road safety schemes can be extremely inexpensive by comparison and can offer extremely high societal benefit. 

An example is the Department for Transport’s latest Safer Roads Fund investment of £47.5million that Road Safety Foundation (RSF) has supported. This is expected to prevent 760 deaths and serious injuries over the next 20 years, with a societal benefit of £420m and a BCR of 7.4.

Measuring safety performance

Whether or not you agree that the most expensive road schemes are typically on already best-performing roads, while the worst-performing roads get low budgets by comparison, depends on how you measure road safety performance. If you work on just the basis of crash rates (fatal and serious injuries per vehicle miles driven) then you find yourselves looking at a list of roads that are on the more peripheral parts of our road networks that carry lower levels of traffic. 

If, however, you measure it by crash density, you find yourself on the higher volume roads, which is arguably where most road investment occurs. I prefer a hybrid approach, looking at high crash density (high opportunity to prevent death and serious injury) and low International Road Assessment Programme (iRAP) star rating (indicative of the opportunity to make tangible improvements to the road itself). 
 
There are lots of opportunities to invest in road safety for high societal returns and we won’t run out of high investment potential routes for a very long time. That means we do need greater levels of investment in road safety schemes on strategic, major and local roads.

Delivering more safety savings

We also have an opportunity to ensure that whenever any road investment happens, that we maximise the road safety returns. By applying the iRAP methodology to route optimisation or to designs we can estimate the number of fatal and serious injuries expected for each option being reviewed for vehicle occupants, motorcyclists, pedestrians and cyclists. As designs progress, we can challenge design teams to push harder and deliver more safety savings. We can even set performance standards for new road designs – we can request four-star or better designs, for example. 

We also have an opportunity to bring greater road safety benefit to the transport planning sector, ensuring that when new developments are considered, the quantifiable road safety impact is assessed and safety benefits are delivered.

Dr Suzy Charman was in conversation with Craig Thomas