Some stretches of motorway have this sign:
with chevrons painted on the road.
What is the distance between 2 chevrons, and at what speed does that give a 2 second gap? I’ll post the answer later.
40m, And probably about 45 miles and hour (without doing the maths…)
djw:
Some stretches of motorway have this sign:
with chevrons painted on the road.What is the distance between 2 chevrons, and at what speed does that give a 2 second gap? I’ll post the answer later.
Thank you.
Regards. John.
Have you also noticed that the distance between the chevrons is virtually the same as the distance between lamp posts ?
I think the gap is 60 mph approx.
I tend to use either lane lines or hazards lines with each being 10 mph so 6 lines at 60 mph etc
Evil8Beezle:
40m, And probably about 45 miles and hour (without doing the maths…)
Nearly.
40m is the distance between each chevron (TSGRD 2002, direction 18(7)). If you want to look it up, you’ll find it on the TSGRD online web page for diagram 1064, which is the chevron - open Directions, then 18, and read to the bottom.
This means the distance between two chevrons is 80m.
To work out the speed where a 2 second gap is 80m:
speed = distance / time
speed = 80m / 2s = 40m/s
Divide 40m/s by 0.44704 to convert to mph and you get 89.5mph, which we’ll round to 90mph. Of course, there’s nothing magical about 2s other than it’s a reasonable rule of thumb.
If you do the maths and throw in a small amount of rounding, 80m is:* 3.2s at 56mph
- 3s at 60mph
- 2.5s at 70mph
djw:
Evil8Beezle:
40m, And probably about 45 miles and hour (without doing the maths…)Nearly.
40m is the distance between each chevron (TSGRD 2002, direction 18(7)). If you want to look it up, you’ll find it on the TSGRD online web page for diagram 1064, which is the chevron - open Directions, then 18, and read to the bottom.
This means the distance between two chevrons is 80m.
To work out the speed where a 2 second gap is 80m:
speed = distance / time
speed = 80m / 2s = 40m/sDivide 40m/s by 0.44704 to convert to mph and you get 89.5mph, which we’ll round to 90mph. Of course, there’s nothing magical about 2s other than it’s a reasonable rule of thumb.
If you do the maths and throw in a small amount of rounding, 80m is:* 3.2s at 56mph
- 3s at 60mph
- 2.5s at 70mph
I’m confused! 
- Is the distance between each chevron, different to the distance between 2 chevrons? (I might be a bit drunk as well…) 
There’s 40m from the start of one chevron to the start of the next chevron.
The intention is that you drive no closer than two chevrons apart, which means an 80m gap (two lots of 40m).
40m ?
They look closer than that. Mind you, I tried (with success) to run across a motorway once when I was a kid and you don’t realise how wide they are until you actually try and cross one. You certainly don’t appreciate the distance travelling along one in a vehicle.
Why do we need a sign to keep the gap ?
For HGV’s-Just count one thousand and two thousand and three thousand and four thousand slowly (2 second gap is for cars)
I know the Numptys will fill the gap, but just be an adult & maintain the gap.
But then there’s no Counting for the Hero 44ton Tailgators !
martinviking:
Why do we need a sign to keep the gap ?For HGV’s-Just count one thousand and two thousand and three thousand and four thousand slowly (2 second gap is for cars)
I know the Numptys will fill the gap, but just be an adult & maintain the gap.But then there’s no Counting for the Hero 44ton Tailgators !
Many truck drivers don’t need signs. They seem to run by the rule that if you can read the number plate on the car in front then they’re not close enough 
martinviking:
For HGV’s-Just count one thousand and two thousand and three thousand and four thousand slowly (2 second gap is for cars)
I know the Numptys will fill the gap, but just be an adult & maintain the gap.But then there’s no Counting for the Hero 44ton Tailgators !
All very true. If you’re after a 4 second gap when driving an HGV, that amounts to 100m at 90km/h - or 2.5 chevrons if you are in an area where they are painted.
There’s an awful lot of vehicles go through these areas not even one chevron apart.
Different opinions if these actually work or not.
Idea to stop rear end shunts ?
People driving perfectly adequately see signs and adjust speed/slam on causing the “ripple effect” and unnecessary phantom queues or rear end shunts 
I did hear as and it wouldn’t surprise me that someone came up with the idea as an “incident prevention measure” and got a cash bonus,
Then someone else came along with an idea to remove them as an “incident prevention measure” and got a cash bonus
djw:
Evil8Beezle:
40m, And probably about 45 miles and hour (without doing the maths…)Nearly.
40m is the distance between each chevron (TSGRD 2002, direction 18(7)). If you want to look it up, you’ll find it on the TSGRD online web page for diagram 1064, which is the chevron - open Directions, then 18, and read to the bottom.
This means the distance between two chevrons is 80m.
To work out the speed where a 2 second gap is 80m:
speed = distance / time
speed = 80m / 2s = 40m/sDivide 40m/s by 0.44704 to convert to mph and you get 89.5mph, which we’ll round to 90mph. Of course, there’s nothing magical about 2s other than it’s a reasonable rule of thumb.
If you do the maths and throw in a small amount of rounding, 80m is:* 3.2s at 56mph
- 3s at 60mph
- 2.5s at 70mph
Surely using that calculation means keeping 3 chevrons apart? If there’s only 2 painted chevrons between you and the vehicle in front then there’s only going to be 1 x 40m gap, exactly as pictured in the sign. 2 painted chevrons and 1 gap. To get 90m you’re going to have to see 3 chevrons and 2 gaps, which is nothing like shown on the sign.
The idea is that you measure chevron, gap, chevron, gap and then to the very beginning of the third chevron.
The sign should really show the distant car on top of a chevron.
Anyone remember about 12 years ago on the M62 between Junctions 23 and 22 when they painted all the chevrons upside down in a V then spent the following week burning them all off and repainting them the right way up.
I was trundling along the M62 at 70 on my motorbike last year when a Subaru blasted past me. I had to accelerate like mad and cling on for dear life just to keep 2 chevrons between us. It’s a stupid rule and quite dangerous!
TerryDactyl.:
I was trundling along the M62 at 70 on my motorbike last year when a Subaru blasted past me. I had to accelerate like mad and cling on for dear life just to keep 2 chevrons between us. It’s a stupid rule and quite dangerous!
Class, 10 out of 10.
djw:
40m is the distance between each chevron (TSGRD 2002, direction 18(7)). If you want to look it up, you’ll find it on the TSGRD online web page for diagram 1064, which is the chevron - open Directions, then 18, and read to the bottom.This means the distance between two chevrons is 80m.
To work out the speed where a 2 second gap is 80m:
speed = distance / time
speed = 80m / 2s = 40m/sDivide 40m/s by 0.44704 to convert to mph and you get 89.5mph, which we’ll round to 90mph. Of course, there’s nothing magical about 2s other than it’s a reasonable rule of thumb.
If you do the maths and throw in a small amount of rounding, 80m is:* 3.2s at 56mph
- 3s at 60mph
- 2.5s at 70mph
i’m sure there are more fun things in life than researching road markings
moomooland:
Anyone remember about 12 years ago on the M62 between Junctions 23 and 22 when they painted all the chevrons upside down in a V then spent the following week burning them all off and repainting them the right way up.
Oooohhhhhh maybe that’s why you saw some of these lunatics driving wrong way down the motorway!! They saw the chevrons and thought that was the correct way!!!■■
Claretmac:
moomooland:
Anyone remember about 12 years ago on the M62 between Junctions 23 and 22 when they painted all the chevrons upside down in a V then spent the following week burning them all off and repainting them the right way up.Oooohhhhhh maybe that’s why you saw some of these lunatics driving wrong way down the motorway!! They saw the chevrons and thought that was the correct way!!!■■
What do you mean “Some of the Lunatics” when I drove down there, all the Lunatics were driving the wrong way ! [emoji654]️[emoji595][emoji598][emoji592][emoji597][emoji594][emoji609][emoji600][emoji602][emoji603]