Collision numbers

Safety is imperative for us. We want everyone who uses our roads to get home safe and well.

We evaluate the impact of our schemes on safety by considering the number of personal injury collisions (PIC). This dashboard compares

• the numbers of PICs after the project
• the estimate of PICs there would have been without the project (known as the counterfactual)

Negative numbers indicate a reduction in PICs, meaning a safer road.

We consider safety on the scheme extent (the section of road which has been improved) and the wider area (roads beyond the scheme extent that are impacted by the scheme – such as nearby local roads). 

Summary

It's important to consider PICs in the context of traffic levels.

If the amount of travel on our network increased, we'd expect to see more collisions.  This would be the case even if all other factors remain the same.

Collision rate is measured as the number of PICs per hundred million vehicle miles (hmvm) travelled. This metric helps us understand whether:

• the risk of collision has actually changed
• the change in PICs is just a consequence of more (or less) traffic

Overall safety has improved as a result of our schemes, indicated by fewer PICs and lower collision rates.