Safety

Overview 

The evaluation summarises how road safety changed during the first five years after the M1 J45 project opened. It compares safety performance before and after the project to assess whether it has improved conditions for road users and achieved its intended objectives. 

As safety was not a specific objective of the project and was not assessed at appraisal, the five-year evaluation considers observed safety outcomes within the project extent, comprising the M1 mainline, slip roads and roundabout. 

How has road safety changed? 

The evaluation identified improvements in road safety within the project extent. Collision rates, serious collisions and casualty severity all reduced during the five years after opening. 

What impact did the project have on collisions? 

During the five years before project opening, seven personal injury collisions were recorded, averaging 1.4 collisions per year. This reduced to an average of one collision per year in the five years after the project opened. The figure below shows changes in the number of personal injury collisions before the project, during construction and after opening. 

Number of personal injury collisions before the project, during construction, and after the project opened

What impact did the project have on collision rates? 

The average collision rate reduced from 12.5 personal injury collisions per hundred million vehicle miles (hmvm) before opening to 5.0 collisions per hmvm during the five-year evaluation period. 

Has the project contributed to these changes? 

The relatively small number of collisions recorded within the project extent means it is not possible to determine with certainty the extent to which the observed changes are attributable to the project. However, the reductions in collision numbers and collision rates suggest that safety outcomes have improved following project opening 

What impact did the project have on collision severity? 

No fatal collisions were recorded before or after opening. The evaluation found a reduction in the number of serious collisions, although the number of slight collisions increased. Overall, the severity of collisions reduced following project opening.

Number of personal injury collisions by severity

What impact did the project have on killed or seriously injured casualties? 

The impact on casualty severity is measured using the number of killed or seriously injured casualties (KSI) and fatal weighted injuries (FWI).  

The number of KSI casualties reduced from an average of 0.91 before the project opened to 0.05 after opening. The KSI rate also reduced from an average of 9.05 to 0.34 per hundred million vehicle miles (hmvm).  

FWI reduced from an average of 0.11 before opening to 0.02 after opening. The FWI rate also reduced from an average of 0.96 to 0.16 per hmvm. 

Overall, these findings indicate a reduction in the severity of casualties within the project extent following project opening. 

Change in KSI and FWI