Determining speed limits for given route

Question

I am trying to develop an application, which finds a route between two points, and displays current speed limits as you drive.

So far I managed to use OSRM API ( http://project-osrm.org/ ) to get a route geometry (as a list of coordinates) and driving directions (as simple instructions, not correlated with OSM objects). I am also aware, that some ways in OSM provide numeric values of speed limits in their tags. What I don't know is how to cherry-pick the needed ways from Overpass API (ideally without any excessive data) and how to associate my route geometry with proper limits. Or maybe there is an other, more comprehensive tool capable of satisfying my needs?

Thank you in advance for any help!

EDIT: I already received a great answer for my problem, but out of curiosity I would also appreciate a solution which does not involve interfering in OSRM API

Accepted Answer

It may be easier to do this by setting up your own instance of OSRM. You can then return the speed limit as part of the turn-by-turn directions, rather than just the road number.

You would typically do this in the Lua profile of your OSRM instance. In way_function, after way.name has been set to the ref/name, add code such as this:

if maxspeed>0 then way.name=way.name.."|"..maxspeed end

In other words, if there's a maxspeed value for the way, append it to the way name, separated by a | symbol.

You can then parse this value in your JavaScript (or other) client.

Answer 2

For the current version of API I used this temporary solution, analogous to the above mentioned. Using the car.lua profile you may insert the maxspeed attribute as part of other attributes. This could be done on multiple places. I added the

local maxspeed = parse_maxspeed( way:get_value_by_key("maxspeed") )

on line 430 and then on line 446 changed the code to

result.ref = ref.."|"..maxspeed

This is a very simple way but not really standard. I would like to create a separate JSON attribute for maxspeed in the response of API.

Answer 3

Hey! Is there a similar solution for the current version? I really don't know where to put the suggested lines of code. Or respectively how to modify them to either adding the maxspeed attribute to another attribute or creating a new attribute in the output. That would be of great help for me - many thanks in advance.

Determining speed limits for given route

Related questions