[OSRM-talk] profile.lua car.lua tuning
michael at chesterton.id.au
Thu Nov 5 14:35:37 UTC 2015
A bit of a long one.
I've read a few messages from this list about tuning car.lua,
not all of them yet, but the ones i have read were different
problems, my problem is it's too fast. If a trip would take 30
minutes in real life, osrm might say it takes 20 minutes.
primarily because of congestion in the city.
Firstly I can lower the speed of roads, and that works in the city,
but now trips 30+km outside the city are too slow.
If I penalise traffic lights more (the default is 2, and I think that
is 2 seconds based on a comment in another lua file, which to me
is surprisingly short) osrm starts going to great lengths to avoid them,
with lots of turns. So I penalise turns more, then i mess up the
penalise right hand turns more than left hand turns algorithm,
and the trip api plans a route with more right hand turns than
with a default profile.lua with one change
local turn_bias = 0.7
everything is good except it's to fast in the city.
If I make one extra change,
local turn_penalty = 40
which is too expensive, but i'm just testing, it starts favouring
right hand turns.
Can someone make sense of this and offer a fix or a suggestion?
Maths and computer science algorithms aren't my strong point.
If I do the turn calculations by hand for a 90 degree turn,
right hand turns cost 57
left hand turns cost 28
local turn_penalty = 20
favours left hand turns, good. then I make one more change
traffic_signal_penalty = 20
and it starts favouring right hand turns again :(
another question, assuming 3 left hand turns around the block cost
more than 1 right hand turn, does the turn bias affect viaroute, or is
it mainly only trip?
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