Motorway driving in heavy rain
Discussion
Flat in Fifth said:
The most common experience of aquaplaning I have is on roads where ruts have been worn by passage of vehicles with studded tyres during the winter. It is difficult to avoid other than by driving out of position and on clear sections of the road surface.
One of the most peculiar experiences I've had on the road occurred when I was driving cross country in heavy rain and stopped for fuel. Pulling out of the filling station back onto the rather battered dual carriageway it seemed to me that something wasn't quite right, but I couldn't quite put my finger on the problem. The steering, acceleration and brakes all seemed connected (but still not quite normal somehow) so I carried on at slower speed than normal trying to figure out what the problem was. Fairly shortly I arrived at a sweeping bend which was slightly banked, and I found myself unexpectedly sliding down the banking into the next lane with no steering control at all. After I'd moved a few feet sideways the car lurched, the speedo reading dropped by about 15 mph and I found myself pootling along with everything back to normal. I'd been aquaplaning in the standing water in the grooves in lane 1 for probably the best part of a minute, with the tyres having just enough purchase on the sides of the grooves to give me steering and acceleration.
As we all know water is a liquid, and as we all know water cannot be compressed to any significant degree, and as we all know jumping off the high board into a pool of water is fine as long as you do not belly flop or similar.
So consider something travelling at 65 MPH, with a layer of water on road, what happens? we know water is not compressed to any significant degree,
so MPH+tyres+pool of water = aquaplaning, aquaplaning = loss of tyre contact with road = loss of control and directional stability.
There does not have to be standing water, any heavy downpour, such as we have had recently, can produce a sufficient depth of water, standing or running, to induce aquaplaning, which in my experience, with 39 years of driving in the UK and 14 other countries around the world, will occur when the vehicle is traveling at approx 50 MPH, incorrect inflation, uneven wear, and low tread depth will all aggrevate the situation.
So when all else fails, do not forget to slow down and drive to suit the weather conditions.
So consider something travelling at 65 MPH, with a layer of water on road, what happens? we know water is not compressed to any significant degree,
so MPH+tyres+pool of water = aquaplaning, aquaplaning = loss of tyre contact with road = loss of control and directional stability.
There does not have to be standing water, any heavy downpour, such as we have had recently, can produce a sufficient depth of water, standing or running, to induce aquaplaning, which in my experience, with 39 years of driving in the UK and 14 other countries around the world, will occur when the vehicle is traveling at approx 50 MPH, incorrect inflation, uneven wear, and low tread depth will all aggrevate the situation.
So when all else fails, do not forget to slow down and drive to suit the weather conditions.
SLCZ3 said:
As we all know water is a liquid, and as we all know water cannot be compressed to any significant degree, and as we all know jumping off the high board into a pool of water is fine as long as you do not belly flop or similar.
So consider something travelling at 65 MPH, with a layer of water on road, what happens? we know water is not compressed to any significant degree,
so MPH+tyres+pool of water = aquaplaning, aquaplaning = loss of tyre contact with road = loss of control and directional stability.
There does not have to be standing water, any heavy downpour, such as we have had recently, can produce a sufficient depth of water, standing or running, to induce aquaplaning, which in my experience, with 39 years of driving in the UK and 14 other countries around the world, will occur when the vehicle is traveling at approx 50 MPH, incorrect inflation, uneven wear, and low tread depth will all aggrevate the situation.
So when all else fails, do not forget to slow down and drive to suit the weather conditions.
That last sentence is a timely reminder of course, and always good to bear in mind, but I do think you're mistaken in your assertion that aquaplaning will occur at approx. 50 mph. etc. If anyone were to take that as a guide to a safe driving speed in wet conditions they could be misled. I suggest the whole situation is more complicated that you're implying, and deciding on a suitable speed without going unnecessarily slowly, or travelling dangerously fast, requires a fairly accurate judgement of quite a variety of factors.So consider something travelling at 65 MPH, with a layer of water on road, what happens? we know water is not compressed to any significant degree,
so MPH+tyres+pool of water = aquaplaning, aquaplaning = loss of tyre contact with road = loss of control and directional stability.
There does not have to be standing water, any heavy downpour, such as we have had recently, can produce a sufficient depth of water, standing or running, to induce aquaplaning, which in my experience, with 39 years of driving in the UK and 14 other countries around the world, will occur when the vehicle is traveling at approx 50 MPH, incorrect inflation, uneven wear, and low tread depth will all aggrevate the situation.
So when all else fails, do not forget to slow down and drive to suit the weather conditions.
Best wishes all,
Dave.
As i said approx is approx, and i have always ensured that my tyres are in very good condition and actually change them well before the legal minimum, and make sure in conditiions suitable for aquaplaning that i travel at a velocity that i think will be below the aquaplane threshold if i feel that the vehicle is starting to auqaplane, or there are areas of standing water and puddles that are present then i slow down again, and i must say that i have never experienced aquaplaning below 45 MPH.
In Spain I have found all the newest A roads and motorways in the South, are properly cambered whether on a bend or straight, and are well drained so you don't often get a lot of standing water. Also due to the lack of traffic i find them both relaxing to drive and they make for quick A-B progress with no hassle staying within resonable limits.
Bearing in mind the sheer amount of heavy wet weather we get in the UK i don't understand why they don't often do the same here. I have regularly noticed that on a lot of UK roads both old and new, the cambers on bends are going the wrong way, there is always a lot of standing water, and motorway straights seem to be cambered so the majority of standing water ends up in lane 3.
Why??
Bearing in mind the sheer amount of heavy wet weather we get in the UK i don't understand why they don't often do the same here. I have regularly noticed that on a lot of UK roads both old and new, the cambers on bends are going the wrong way, there is always a lot of standing water, and motorway straights seem to be cambered so the majority of standing water ends up in lane 3.
Why??
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