Discussion
In my last IAM classroom session, where an examiner was our guest speaker, he mentioned something about 'half distance' and the use of acceleration sense in relation to approaching static hazards (junctions, roundabouts etc).
I never got the opportunity to ask further about it, my observer is on holiday and I can't anything in the IAM book.
Can anyone expand?
I have my pre-test this evening so any last minute advice on that too would be much appreciated!
Cheers
Steve
I never got the opportunity to ask further about it, my observer is on holiday and I can't anything in the IAM book.
Can anyone expand?
I have my pre-test this evening so any last minute advice on that too would be much appreciated!
Cheers
Steve
Could be one of two things:
1) On single track roads, you ought to be driving at a speed where you can stop in half the distance you can see to be clear, because the oncoming vehicle is going to need the other half
2) When overtaking you should be able to complete the overtake in half the time (and this isn't quite the same thing as half the distance, if you imagine the oncomer is something like a bike with plenty of acceleration capability) that you can see to be clear.
1) On single track roads, you ought to be driving at a speed where you can stop in half the distance you can see to be clear, because the oncoming vehicle is going to need the other half
2) When overtaking you should be able to complete the overtake in half the time (and this isn't quite the same thing as half the distance, if you imagine the oncomer is something like a bike with plenty of acceleration capability) that you can see to be clear.
If it was in connection with acceleration sense it sounds like a variation on the thirds rule.
It's a rule of thumb for deciding when to stop accelerating and start braking when driving between 2 hazards.
Often people are told accelerate for one third of the distance, maintain speed for the next third, then slow down during the remaining third.
If you accelerate for half the distance you get more progress at the expense of economy.
The more progress you want to make, the longer your acceleration and the shorter/firmer your braking. The ultimate example being track driving where you go straight from full power to full braking at the last moment. You probably wouldn't go quite that far on the road.
It's a rule of thumb for deciding when to stop accelerating and start braking when driving between 2 hazards.
Often people are told accelerate for one third of the distance, maintain speed for the next third, then slow down during the remaining third.
If you accelerate for half the distance you get more progress at the expense of economy.
The more progress you want to make, the longer your acceleration and the shorter/firmer your braking. The ultimate example being track driving where you go straight from full power to full braking at the last moment. You probably wouldn't go quite that far on the road.
Edited by Z.B on Thursday 22 April 11:02
Dave - Not quite what I was thinking of but good points to consider all the same.
Z.B - This sounds similar to what the examiner was discussing. The part I had difficulty grasping was that your halfway point will always be changing as you move towards the hazard.
Think I will stick with perfecting limit points before trying this!
Thanks for your input.
Z.B - This sounds similar to what the examiner was discussing. The part I had difficulty grasping was that your halfway point will always be changing as you move towards the hazard.
Think I will stick with perfecting limit points before trying this!
Thanks for your input.
I was taught the 60/40 rule.
I.E. you round a corner on to a straight piece of road. In 1000 yards you can see there is a bend, so you can accelerate or maintain speed for the first 60% (600 yards) but the remaining 40% should be used to determine and action what you need to do next, IIRC.
I.E. you round a corner on to a straight piece of road. In 1000 yards you can see there is a bend, so you can accelerate or maintain speed for the first 60% (600 yards) but the remaining 40% should be used to determine and action what you need to do next, IIRC.
rfn said:
I was taught the 60/40 rule.
I.E. you round a corner on to a straight piece of road. In 1000 yards you can see there is a bend, so you can accelerate or maintain speed for the first 60% (600 yards) but the remaining 40% should be used to determine and action what you need to do next, IIRC.
Would be interesting to apply that logic in the Nevada desert when you round a corner and there is a 5 mile (or more) straight to the next bend. Maintain speed for 3 miles and 2 miles should be used to determine and action what you need to do next! Now that's what I call thinking distance! :-)I.E. you round a corner on to a straight piece of road. In 1000 yards you can see there is a bend, so you can accelerate or maintain speed for the first 60% (600 yards) but the remaining 40% should be used to determine and action what you need to do next, IIRC.
Glosphil said:
Would be interesting to apply that logic in the Nevada desert when you round a corner and there is a 5 mile (or more) straight to the next bend. Maintain speed for 3 miles and 2 miles should be used to determine and action what you need to do next! Now that's what I call thinking distance! :-)
But I understand traffic there can be travelling in excess of 600 mph...
That gives about 12 seconds to think.
Z.B said:
But I understand traffic there can be travelling in excess of 600 mph...
That gives about 12 seconds to think.
Worth watching the cockpit footage from Andy Green in Thrust SSC going supersonic.That gives about 12 seconds to think.
http://www.youtube.com/watch?v=vHnNxMJLfvA
Good commentary too.
7db said:
Z.B said:
But I understand traffic there can be travelling in excess of 600 mph...
That gives about 12 seconds to think.
Worth watching the cockpit footage from Andy Green in Thrust SSC going supersonic.That gives about 12 seconds to think.
http://www.youtube.com/watch?v=vHnNxMJLfvA
Good commentary too.
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