Speed limit data from api and intersecting roads / over or underpass different speed limits


I am using the api to return the speed limit of any given location by passing the long / lat to the api. This call occurs every 3 seconds

The issue I have is as I pass over an intersecting street, adjoining side street or road / over / underpass often it returns the speed limit of that other road which is not the road I am travelling on and it often has a different speed limits to the road I am driving on.

Also do the speed limit locations co originate line reference the centre line of the road rather than the left side to be able to avoid referencing speed limits of T-intersecting side streets ??? in addition to the above issue of intersecting streets

Can anyone advise what I need to do so resolve this issue.

have you maybe tried ‘heading’ parameter? it is designed exactly for the case you mentioned - it allows algorithm to recognize in which direction user is driving (and it tells that user is moving) - and in reulst this improves matching algorithm.

Hi thanks for your reply

no I have not so is it dimply &heading=[degree value 0-360] ???

Also does this address issue the passing side streets or Parallel service roads ???

Does the system take co ordinates from centre line of each road or curb side line ???

“so is it dimply &heading=[degree value 0-360] ???”
yes, 0 is north, more here:

it should solve issue with matching to perpendicular roads on crossroads (if you are heading north then it won’t match to east heading road)…
it might not solve issues with ‘Parallel’ roads - if you could please give some examples where it fails then I could investigate it deeper,

“Does the system take co ordinates from centre line of each road or curb side line ???”
usually - local road is represented as a single line, by adding heading you also tell right of left direction of road (they may have different speed limits),
bigger roads might be represented as more than 1 line (matching lanes especially if they are separated by grass or something similar)

btw. ofc. you can think about reducing probing time, for example from 3 seconds to 1, I would expect better results with it, ofc. it would affect number of transactions/cost