The Government has not commissioned research on the impact of surface water on road safety. However, guidance in the Highway Code, Wet Weather (Rule 227), is based on evidence on wet weather and typical stopping distances.
The Highway Code, Wet Weather (Rule 227):
In wet weather, stopping distances will be at least double those required for stopping on dry roads (see ‘Typical stopping distances). This is because your tyres have less grip on the road. In wet weather:
- you should keep well back from the vehicle in front. This will increase your ability to see and plan ahead
- if the steering becomes unresponsive, it probably means that water is preventing the tyres from gripping the road. Ease off the accelerator and slow down gradually
- the rain and spray from vehicles may make it difficult to see and be seen
- be aware of the dangers of spilt diesel that will make the surface very slippery (see Annex 6: Vehicle maintenance, safety and security)
- take extra care around pedestrians, cyclists, motorcyclists and horse riders.