Chris Bertram wrote:What is the disadvantage in being precise? If you know it's 190 yds to the Give Way sign, why not say so?
Because round numbers (to one significant figure) are easier to process than those with extra digits. Most drivers can read and visualise 200yds quicker than 190yds, but in practical terms they are the same, drivers wouldn't be able to distinguish the difference between them.
Also I'm fairly sure the TSM is clear that rounding of distances is preferred for ease of comprehension when travelling at speed.
It's also why imperial bridge heights should always be in multiples of 3 inches.
Bryn Terminally cynical, unimpressed, and nearly Middle Age already. She said life was like a motorway; dull, grey, and long.
Chris Bertram wrote:What is the disadvantage in being precise? If you know it's 190 yds to the Give Way sign, why not say so?
Because round numbers (to one significant figure) are easier to process than those with extra digits. Most drivers can read and visualise 200yds quicker than 190yds, but in practical terms they are the same, drivers wouldn't be able to distinguish the difference between them.
Also I'm fairly sure the TSM is clear that rounding of distances is preferred for ease of comprehension when travelling at speed.
It's also why imperial bridge heights should always be in multiples of 3 inches.
Perhaps metric bridge heights should be rounded to the nearest 0.1metres then?
Stevie D wrote:
Because round numbers (to one significant figure) are easier to process than those with extra digits. Most drivers can read and visualise 200yds quicker than 190yds, but in practical terms they are the same, drivers wouldn't be able to distinguish the difference between them.
Also I'm fairly sure the TSM is clear that rounding of distances is preferred for ease of comprehension when travelling at speed.
It's also why imperial bridge heights should always be in multiples of 3 inches.
Perhaps metric bridge heights should be rounded to the nearest 0.1metres then?
So if a bridge is actually 10' 2" high, it has to be signed as 10' dead, because it doesn't make 10' 3"?? And the same if it was 10' 4"??
This is perhaps my point about the metric mile being 1.5 k's to the mile. It would be far easier to convert - mentally, and on the ground (in terms of signage).
Stevie D wrote:
Because round numbers (to one significant figure) are easier to process than those with extra digits. Most drivers can read and visualise 200yds quicker than 190yds, but in practical terms they are the same, drivers wouldn't be able to distinguish the difference between them.
Also I'm fairly sure the TSM is clear that rounding of distances is preferred for ease of comprehension when travelling at speed.
It's also why imperial bridge heights should always be in multiples of 3 inches.
Perhaps metric bridge heights should be rounded to the nearest 0.1metres then?
They are.
A bridge that is 14 ft 11 inches would be signed at 4.5m / 14ft 9in.
The rounding rules are covered extensively in Traffic Signs Manual Chapter 4.
Bryn Terminally cynical, unimpressed, and nearly Middle Age already. She said life was like a motorway; dull, grey, and long.
Casino Manager: "It was a good night. Nothing Unusual."
Harold Shand: "Nothing unusual," he says! Eric's been blown to smithereens, Colin's been carved up, and I've got a bomb in me casino, and you say nothing unusual ?"
Unfortunately I don't have any photos of them, or could find any on Gmaps. But when I was driving up the M23, in the roadworks they have got height restriction signs under every guantry and bridge, rounded to the nearest 0.1cm
So you get signs like 5.188m
I think it is a bit unnecessary tbh
Bryn666 wrote:
Also I'm fairly sure the TSM is clear that rounding of distances is preferred for ease of comprehension when travelling at speed.
It's also why imperial bridge heights should always be in multiples of 3 inches.
Perhaps metric bridge heights should be rounded to the nearest 0.1metres then?
They are.
A bridge that is 14 ft 11 inches would be signed at 4.5m / 14ft 9in.
The rounding rules are covered extensively in Traffic Signs Manual Chapter 4.
Actually 4ft 11in would be rounded down to 14ft 6in. not 14ft 9in.
The metric equivalent of 4.5466 m would be rounded down to 4.4 m.
In both cases an initial safety factor of 3 inches or 7 cm is built into the rounding.