[OSM-talk] Maxheight changes

[Ben Laenen]

Steve Bennett wrote:
> On Sat, Jan 2, 2010 at 12:14 AM, Dave F. <davefox at madasafish.com> wrote:
> > I don't why he feels the need to do this, it seems a pointless task, but
> > why do you think it reduces accuracy to remove trailing zeros?
> >
> > 2m =2.0m
> 
> It reduces *indication of accuracy*.
> 
> There's a difference between "I measured that bridge, and it's 2 metres
> high" and "I measured that bridge, and it's 2.000 metres high". If the
> signposted maximum height under the bridge is 2.0m, it should be recorded
>  as 2.0, not as 2. Especially since for such things, 10 centimetres here or
>  there is pretty significant.

While I agree that we should put in the tag whatever there is on the sign, 
maxheight=2 has absolutely no different meaning than maxheight=2.000000000. If 
something over that height isn't allowed, then it doesn't matter how many 
zeros you add. If your car is 2.000000001 meters high, you're not allowed, 
period (albeit chances of getting caught are very slim, as no ruler could 
measure it that accurately anyway, but that has nothing to do with the number 
of trailing zeros on the sign, but with the devices used for measuring). 
Telling maxheight=2 doesn't mean that cars between 1.5m and 2m have to watch 
out because they might not fit under the bridge.

But on measured numbers, those trailing zeros are important indeed. "That 
bridge is 2 meters high", or "that bridge is 2.00 meters high": these 
sentences do mean different things. I'd be much more confident driving my 
1.90m high car under that second bridge.

So, numbers on signs about restrictions (maximum speed, maximum height, 
maximum length, maximum weight...): trailing zeros have no value, as those 
numbers are "exact". Numbers about measurements (elevation, height of a 
bridge, road width): trailing zeros do have value.

Greetings
Ben