For those people who drive everywhere at 20mph

[Xt500]

As I've said, I just don't buy the argument that 20mph drivers are a problem.

 

But with this thread in mind I brought up the subject with my brother-in-law at the weekend because he lives in a Cotswold village so needs to drive everywhere and he's always moaning about slow drivers.

 

He looked puzzled when I mentioned slow drivers though. It's not slow drivers that's the problem, it's fast drivers he said. Their village has one of those smiley face flashing signs thingys, and the average is closer to 40mph than the 30mph limit.

 

What annoys them is "slower" traffic, on the "A" roads like Fosse Way. Drivers doing 50mph when the limit is 70mph, or 40mph when it is 50mph, infuriate them. Lots of holiday traffic, caravans, agricultural vehicles are all part of the annoyance of living in a picturesque Cotswold village. But ...

 

There are no shops in their village any more, or the neighbouring ones. They all disappeared with the growth of the supermarkets and their nearest one is 15 miles away, and there is no bus service. Car ownership is vital. Some of their neighbours are elderly and get the car out of their garages once a week to get supplies, keep in touch with family. Many of them might be more confident driving at 40mph rather than 50mph, and therein lies the paradox of complaining about slower drivers.

 

It might be an easy throwaway remark for a young able-bodied person to spout demands about slow drivers being off the road, but who's to say that his/her 5 mins home earlier is more important than somebody else's shopping, or connection with family and friends? Will he/she be so quick to follow their own advice if/when they become less confident at speed? People might get slower as they get older, but they also might become more dependant on the car, so who are we to make demands about speed?

 

Its generally not speed thats the problem,slow speed is usually coupled with inability and selfishness and in some cases dangerous.

 

i note you assume everybody is going a couple of miles down the road and this poor standard of driving causes just a five minute delay,that isnt the case for many drivers but IS a token of the selfish attitude that slower drivers have.They dont care about anyone but themselfs and you make that point.

[EASTWOOD141]

Its generally not speed thats the problem,slow speed is usually coupled with inability and selfishness and in some cases dangerous.

 

i note you assume everybody is going a couple of miles down the road and this poor standard of driving causes just a five minute delay,that isnt the case for many drivers but IS a token of the selfish attitude that slower drivers have.They dont care about anyone but themselfs and you make that point.

You are right! I would love to be sat in the cars of some of these people who condone slow irritating selfish drivers stuck behind their own kind and see their reactions.

[Xt500]

I don't suppose you'd notice the inconsistencies of fast drivers speeds whilst driving a trunk 100k miles a year.

 

At least i could branch out

 

---------- Post added 05-04-2013 at 17:42 ----------

 

You are right! I would love to be sat in the cars of some of these people who condone slow irritating selfish drivers stuck behind their own kind and see their reactions.

 

I wouldnt it would be too nerve racking

[SportsTrophy]

Well done to those that drive at a top speed of 20mph in 20mph zones. Please get in touch for your medal.

 

Stopping distance at 20mph is 40ft so make sure you can see that far. If there are any obstructions like CARS PARKED ON THE PATH then you need to slow down even more.

 

When on a 40mph road do you slow down to 30mph or even 20mph when passing pedestrians on the path at the side of the road?

[Unisol]

Well done to those that drive at a top speed of 20mph in 20mph zones. Please get in touch for your medal.

 

Stopping distance at 20mph is 40ft so make sure you can see that far. If there are any obstructions like CARS PARKED ON THE PATH then you need to slow down even more.

 

When on a 40mph road do you slow down to 30mph or even 20mph when passing pedestrians on the path at the side of the road?

 

I reckon I could stop in under 10ft at 20mph without skidding.

 

Cars have pretty good braking systems now.

[Cyclone]

The length of a large dining table... Including your reaction time?

 

---------- Post added 05-04-2013 at 21:24 ----------

 

http://www.passmytheory.co.uk/learningcentre/stoppingdistance.aspx

 

Apparently half of that 40ft is thinking distance, but what are they saying with that.

 

20mph is approx 9 m/s, so they're giving 2/3rds of a second reaction time... Last time I tested my reactions they were more like <300ms. So that's half the thinking distance they are allowing.

 

They are also saying that the 'average car' (remember these were based on the Ford Anglia) takes 6m to stop after you've hit the brake.

 

S = ut + 1/2att

 

6 = 9t +1/2att

 

t= 6/a

 

6 = 54/a + 18/a

 

6 = 72/a

 

12m/s/s

 

That's the deceleration they are attributing to a car under maximal braking, about 1.2g.

 

An F1 car can hit 6g under maximal deceleration, but that doesn't tell us much really, we don't drive F1 cars.

 

A top end Porsche can stop from 60mph in 31 metres... That's nearly half the distance quoted by the table, so it's pulling over 2g.

 

I'm losing interest, but basically, the table is a massive over exaggeration of the distance a modern car takes to stop. Okay, we can't all react in 200ms like a fighter pilot, and we don't all drive a Porsche, but even so, at 20mph it's probably more like 4 metres than 6.

 

---------- Post added 05-04-2013 at 21:29 ----------

 

http://www.motortrend.com/features/mt_hot_list/1112_22_cars_that_stop_from_mph_in_less_than_100_feet/viewall.html

 

Even the lowly Porsche boxter can stop in <100 ft from 60mph. Supposedly that should take 180ft plus reaction time.

[DT Ralge]

The length of a large dining table... Including your reaction time?

 

---------- Post added 05-04-2013 at 21:24 ----------

 

http://www.passmytheory.co.uk/learningcentre/stoppingdistance.aspx

 

Apparently half of that 40ft is thinking distance, but what are they saying with that.

 

20mph is approx 9 m/s, so they're giving 2/3rds of a second reaction time... Last time I tested my reactions they were more like <300ms. So that's half the thinking distance they are allowing.

 

They are also saying that the 'average car' (remember these were based on the Ford Anglia) takes 6m to stop after you've hit the brake.

 

S = ut + 1/2att

 

6 = 9t +1/2att

 

t= 6/a

 

6 = 54/a + 18/a

 

6 = 72/a

 

12m/s/s

 

That's the deceleration they are attributing to a car under maximal braking, about 1.2g.

 

An F1 car can hit 6g under maximal deceleration, but that doesn't tell us much really, we don't drive F1 cars.

 

A top end Porsche can stop from 60mph in 31 metres... That's nearly half the distance quoted by the table, so it's pulling over 2g.

 

I'm losing interest, but basically, the table is a massive over exaggeration of the distance a modern car takes to stop. Okay, we can't all react in 200ms like a fighter pilot, and we don't all drive a Porsche, but even so, at 20mph it's probably more like 4 metres than 6.

 

---------- Post added 05-04-2013 at 21:29 ----------

 

http://www.motortrend.com/features/mt_hot_list/1112_22_cars_that_stop_from_mph_in_less_than_100_feet/viewall.html

 

Even the lowly Porsche boxter can stop in <100 ft from 60mph. Supposedly that should take 180ft plus reaction time.

 

Impressive calculations though I doubt anyone at the wheel could make use of them or the HC table.

Research by Direct Line and TRL suggests that reaction time in a driver of average ability is more like 1 second. 0.3 second is stated to be what M Schumacher was timed at. Are you related?

The problem with slagging off the HC figures is that reality is so variable (speed, surface, tyres - inflation and tread), kinetic energy of vehicle bla bla and the slagging off MAY generate poor attitude, over-confidence and over-reliance on technology (what is ABS? what does it do? Questions which many over-reliant drivers fail to answer convincingly) and, oh, does the pedestrian know that your vehicle can stop in x metres rather than x+5 metres and make a rational decision on when to move or not, based on what vehicle is approaching?

[Xt500]

Braking distances are an almost nonesence.no 2 vehicles are the same.2 brand new vehicles the same one full of fuel and one empty would be different.

I never bothered to learn them i didnt see the point,but with that said i always know within inches where i can stop if need be.

[autumn]

Just taken my son to the Station .I was traveling at 22 miles per hour so goodness knows what the Moron was doing in front of me . This was on Penistone rd as well so as you can imagine on a Saturday afternoon massive tailback . When I finally got the chance to over take I expected to see a little old lady at the wheel ,no a man in his thirties .

[Cyclone]

Just taken my son to the Station .I was traveling at 22 miles per hour so goodness knows what the Moron was doing in front of me . This was on Penistone rd as well so as you can imagine on a Saturday afternoon massive tailback . When I finally got the chance to over take I expected to see a little old lady at the wheel ,no a man in his thirties .

 

Presumably he was also doing 22mph, unless you ran into the back of him...

 

Which bit of Penistone Road doesn't have two lanes such that you couldn't overtake easily?

 

---------- Post added 11-04-2013 at 10:42 ----------

 

Impressive calculations though I doubt anyone at the wheel could make use of them or the HC table.

Research by Direct Line and TRL suggests that reaction time in a driver of average ability is more like 1 second. 0.3 second is stated to be what M Schumacher was timed at. Are you related?

The problem with slagging off the HC figures is that reality is so variable (speed, surface, tyres - inflation and tread), kinetic energy of vehicle bla bla and the slagging off MAY generate poor attitude, over-confidence and over-reliance on technology (what is ABS? what does it do? Questions which many over-reliant drivers fail to answer convincingly) and, oh, does the pedestrian know that your vehicle can stop in x metres rather than x+5 metres and make a rational decision on when to move or not, based on what vehicle is approaching?

 

Googling for the results of SM's reaction time, it seems that he is almost bang on he human average. He's an excellent racing driver because of his decision making ability and driving skills, not because of particularly fast reaction speed.

They really are so variable that the table is fairly meaningless, if the data is bad then that's not a reason to avoid criticising it, which is what you seem to be suggesting.