Bemused

Anything that doesn't fit elsewhere - doesn't have to be AD related.
Triquet
Posts: 207
Joined: Tue Sep 29, 2015 7:32 pm

Bemused

Postby Triquet » Mon Feb 12, 2018 5:37 pm

I have just returned from an 80 mile round trip to deliver some stuff. The route was urban and country mostly single-carriageway with a comic variety of speed limits. But once again, the vast majority of the traffic was pootling along at 40 mph irrespective. What is it with 40 mph? It seems to be a sort of default comfort speed for a huge number of people. But why? :gear:

User avatar
akirk
Posts: 1465
Joined: Sun Sep 27, 2015 6:58 pm
Location: Cotswolds

Re: Bemused

Postby akirk » Mon Feb 12, 2018 7:00 pm

is there a NVH sweet spot at 40mph, or simply a point at which you can drive comfortably without having to concentrate on driving?
Alasdair

Triquet
Posts: 207
Joined: Tue Sep 29, 2015 7:32 pm

Re: Bemused

Postby Triquet » Mon Feb 12, 2018 7:31 pm

I think that it is the latter. Hence word "pootle". The only trouble is that they are so oblivious to surroundings that if you overtake they die of shock.

User avatar
Horse
Posts: 1936
Joined: Mon Sep 28, 2015 9:20 am

Re: Bemused

Postby Horse » Mon Feb 12, 2018 8:18 pm

akirk wrote:or simply a point at which you can drive comfortably without having to concentrate on driving?
Alasdair


You might have something there. Look at the way the curve roses at 40:

Image

Could be that it's the maximum multi-task (ie do nothing well, just do more) speed, but also the speed at which vision, planning and action have to be exponentially increased.

I remember reading - but don't know whether it's true - that drivers are more likely to keep to 40 limits than 30s. Perhaps this is why.
My own views. For better or worse :)

User avatar
GTR1400MAN
Posts: 1292
Joined: Fri Apr 29, 2016 12:23 pm

Re: Bemused

Postby GTR1400MAN » Mon Feb 12, 2018 8:30 pm

They keep to 40 alright ... :(

welcome-to-suffolk.jpg
welcome-to-suffolk.jpg (128.99 KiB) Viewed 677 times
Mike Roberts

MrToad
Posts: 64
Joined: Mon Sep 28, 2015 2:28 pm
Location: Bristol

Re: Bemused

Postby MrToad » Mon Feb 12, 2018 10:26 pm

I have this idea that the non-expert driver's gaze settles somewhere not very far in front of their vehicle, and this distance coincides with the stopping distance from roughly 40mph. In other words, at 40mph they'll be able to cope with anything that happens directly in front of them.

This explains the constant pace that doesn't react to the surroundings, and perhaps why they continue at the same speed in lower limits. The (lack of) thinking that leads to this behaviour doesn't consider the possibility of hazards coming from anywhere other than directly in front.

User avatar
Horse
Posts: 1936
Joined: Mon Sep 28, 2015 9:20 am

Re: Bemused

Postby Horse » Tue Feb 13, 2018 8:54 am

Again, you may be onto something too!

Back in the 1970s, a researcher called Hill did a lot of work on vision and driving, including describing perceptual limitations. IIRC, one of those is that we simple wetware humans (although he probably didn't say that, exactly) can't really guage the speed and distance of approaching vehicle when both are traveling above 50mph.

So if he was right, 50 = 'impossible', therefore 40 = comfortable / reasonable / acceptable.
My own views. For better or worse :)


Return to “General Chat”

Who is online

Users browsing this forum: No registered users and 3 guests