Legal time taken to overtake an HGV?
Discussion
Inspired by another thread, how long in terms of time and distance does it take to overtake an HGV legally on a SC road?
It would be interesting to see two examples for the point of discussion. A performance car and something like a Micra.
Example one, Overtake from a safe position without exceeding the limit in both cars.
Example two, full power overtake from a safe position minimising TED in both cars.
I'm rubbish at the maths but I'm sure someone can do it *hint* Any budding mathematicians in here?
It would be interesting to see two examples for the point of discussion. A performance car and something like a Micra.
Example one, Overtake from a safe position without exceeding the limit in both cars.
Example two, full power overtake from a safe position minimising TED in both cars.
I'm rubbish at the maths but I'm sure someone can do it *hint* Any budding mathematicians in here?
Although if one of the cars was a TVR you may have a point! xiphias said:
I can have a go..how long is your average HGV?
That's the starting point. There are a number of other questions to be answered: - Is the HGV going at 40?
- Is the overtaker's max speed 60?
- Is the overtaker doing 60 when it comes upon the HGV, or is it trailing it at 40?
- From how far behind is it trailing it?
- If trailing, from what point do you measure the beginning of the overtake - starting to move into the oncoming lane to have a look, or after that when you've decided it's safe to accelerate?
- What's the overtaker's rate of acceleration?
- At what point is the overtake considered to be complete?
- If that finishing point is when the overtaker's back on the correct side, how rapidly did he make the return?
Perhaps I didn't phrase the question as well as I thought 
There should be four answers, all assuming the truck remains at a constant maximum legally permitted of 40 MPH.
a) Micra overtaking without exceeding 60MPH.
b) Micra overtaking but exceeding 60MPH (if it can).
c) Performance car overtaking but lifting off at 60 MPH.
d) Performance car performing full power overtake ignoring NSL.
There should be four answers, all assuming the truck remains at a constant maximum legally permitted of 40 MPH.
a) Micra overtaking without exceeding 60MPH.
b) Micra overtaking but exceeding 60MPH (if it can).
c) Performance car overtaking but lifting off at 60 MPH.
d) Performance car performing full power overtake ignoring NSL.
flemke said:
xiphias said:
I can have a go..how long is your average HGV?
That's the starting point. There are a number of other questions to be answered: - Is the HGV going at 40?
- Is the overtaker's max speed 60?
- Is the overtaker doing 60 when it comes upon the HGV, or is it trailing it at 40?
- From how far behind is it trailing it?
- If trailing, from what point do you measure the beginning of the overtake - starting to move into the oncoming lane to have a look, or after that when you've decided it's safe to accelerate?
- What's the overtaker's rate of acceleration?
- At what point is the overtake considered to be complete?
- If that finishing point is when the overtaker's back on the correct side, how rapidly did he make the return?
To be realistic, I would assume (being that it's only really worth looking at if it's the "average" driver) that the overtake starts from a 2 second distance behind the lorry at a matching speed to the lorry, and assuming it's safe etc so it's just a simple pull out accelerate and pull in job, assume the car repositions in front of the lorry with say a 3 second distance, and the overtake to be complete as soon as past the white line.
Fish said:
My Atom when I get it will do 50 - 70 in 1.3secs....
That shuld deal with it quite quickly.
A man with performance figures, I like it That shuld deal with it quite quickly.
I can do some of this but I still need help!
Would the following make sense?
Assume a constant starting point two seconds behind the lorry at 40 MPH.
1MPH = .44M/s
@40MPH two seconds will put you 35.2M behind the artic.
The artic is 17M long
The pull in point for comparison (and ease of maths) is 3M in front of the lorry.
eccles said:
what size engine has the micra got?, how old is it (old 80's one or a more modern one?)?
what colour is it? was the roof up or down if it was one of the covertible ones?
Colour, now you're being silly what colour is it? was the roof up or down if it was one of the covertible ones?
I've e-mailed Nissan for 40-60 performance figures as it's actually a serious question. I would like to know how much longer the TED is if you comply with the law versus using your vehicles full capabilities to overtake safely.
Forums | Speed, Plod & the Law | Top of Page | What's New | My Stuff