Floods, Standing Water and Heavy Rain
Advice from the AA's Patrol of the Year
Adam Ashmore, AA patrol of the year for 2007, says: "All drivers, including those with local knowledge, can be caught out during heavy downpours, as even the most modern road surface is still susceptible to standing water. This creates a potential aquaplaning hazard as well as significantly reducing visibility. Drivers should take it easy and if the steering does become unresponsive due to the rain, ease off the accelerator and slow down gradually. "
"If drivers come across flood water, they should only attempt to drive through if they know how deep it is and maintain a steady, slow speed to avoid creating a bow wave."
"The engine's air intake on many cars is low down at the front of the car and it can take just an egg cupful of water in the combustion chamber to wreck an engine. Water doesn't compress and the piston in effect hits a wall, bending or breaking a con rod and possibly shattering the engine block. Driving fast, even if the intake's above the water level could cause water to be ingested."
Adam continues: "If you're unlucky enough to break down in heavy rain, don't prop the bonnet open while you wait for the patrol to arrive – the engine will be more difficult to start again if the electrics are all rain-soaked. Instead, pull over to a safe and visible place and wait for help to arrive."
Heavy rain
Be safe, and prepare for wet weather:
- Check your windscreen wipers before setting off, and replace if necessary - a demonstration is available on one of the AA Patrol Podcasts
- Double the distance you leave between your car and the car in front of you, as stopping distances are increased by wet roads.
- If steering becomes unresponsive due to the rain, ease off the accelerator and slow down gradually.
Floods and standing water
Only drive through water if you know how deep it is.
Drive slowly and steadily to avoid creating a bow wave. Allow oncoming traffic to pass first and test your brakes as soon as you can after leaving the water.
Don't try driving through fast-moving water, such as at a flooded bridge approach – your car could easily be swept away.
Driving fast through standing water is dangerous – tyres lose contact with the road andyou lose steering control in what's known as 'aquaplaning'.
Watch out for standing water, trying to avoid it if you can, and adjust your speed to the conditions. If you do experience aquaplaning, hold the steering wheel lightly and lift off the throttle until the tyres regain grip.
Driving fast through standing water is inconsiderate – driving through water at speeds above a slow crawl can result in water being thrown onto pavements, soaking pedestrians or cyclists. You could face a hefty fine and between three and nine penalty points if the police believe you were driving without reasonable consideration to other road users.
Driving fast through standing water can cause expensive damage – the air intake on many cars is low down at the front of the engine bay and it only takes a small quantity of water sucked into the engine to cause serious damage. All engines are affected but turbo-charged and diesel engines are most vulnerable.
As you drive slowly through standing water keep the engine revving by slipping the clutch, otherwise water in the exhaust could stall the engine.
If you break down in heavy rain don't prop the bonnet open while you wait for the patrol to arrive – the engine will be more difficult to start again if the electrics are all rain-soaked.
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