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Chris Fleming schrieb:
|
http://maps.google.co.uk/maps?f=d&hl=en&geocode=&saddr=Edinburgh&daddr=Newton+Stewart&sll=54.162434,-3.647461&sspn=17.680923,36.079102&ie=UTF8&ll=55.218057,-3.825989&spn=1.073254,2.254944&z=9
| (The route was basically follow the A702 and then the A712, picked
| because it was the most direct route and also because the A712 was
unmapped)
|
| However having traveled down the A712, I can now see why it was
| unmapped, the road was narrow windy and very slow. In fact a friend
| traveling the same route took the A74(M), A701 and the A75 in a quicker
| time.
|
| Now we need some way of tagging "slow" roads, so that we don't pick
| then. I'm not sure if this would be an "average speed" tag or a you'll
| only go 3/4 or half the speed on this road compared to your speed on a
| "normal" A road?
a)
We had multiple suggestions for using collected real-world travel-times.
I'm still up for setting up a web-service to collect these. Maybe
between OpenExpo next week and FOSSGIS.
b)
Does the A702 have fewer lanes?
Is it steeper ("alt"-tag)?
Does it have more curves?
For the "windy" I have though of a simple physics-model a few times
that not only uses the sum of segment-length and the "highway"-tag
but estimates:
* maximum speed a curve with a radius R can be traveled
* maximum speed on differences in altitude
* expected acceleration after a slow segment into a fast segment following.
These speeds and accelerations are user-selected by vehicle-type
~ "car-efficient"=slow acceleration, taking curves fast
~ limited top-speed
~ "car-sporty"=accelerate more but also decellerate in curves,
~ better top-speed
~ "lory"=accelerate very slow and take hills slowly,
~ be very slow ans extreme curves)
~ ...
I think this will break the usual routing-algorithms if applied to
the complete path but between relevant intersections this
could improve a usual time-metric considerably on windy or
steep roads. (Think serpentines up or down a hill)
After calculating the route it can be applied to the complete
path to get a better estimate of an ETA.
c)
Do we have a tag for the state of the road-surface that
is in actual use?
Marcus
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