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Direction of lanes:forward/lanes:backward with (e.g.) oneway=reverse

1

Hi. On the Wiki page of key 'lanes' I read the following: "The key lanes:forward= hereby refers to lanes which direction is equal to the direction of the OSM way, and lanes:backward= to the opposite direction."

My question is: Does this mean that 'lanes:forward' refers to the direction of which the nodes of the way were listed, or the direction of which you can travel on the way? In different terms: For instance, let's say that the way has tag 'oneway'='reverse'. This means that the way of which you can travel on the way (let's call this dirA) is the opposite of how the way was "drawn" (let's call this dirB). Does 'lanes:forward' refer to the number of lanes in direction dirA or in direction dirB? This makes quite a difference for how you would use these numbers.

Thank you for your help.

asked 22 Apr '20, 14:34

issibelli's gravatar image

issibelli
26113
accept rate: 0%


One Answer:

6

The order of the nodes within the way definition. Not the direction of travel.

That said, a number of QA tools will tell you that the oneway=-1 or oneway=reverse is not desireable and strongly suggest you reverse the order of the nodes in the way and use oneway=yes. If you follow that advice, then on oneway roads the direction of travel and the order of the nodes is the same. But then in that case you also don't need to worry about lanes:backward or lanes:forward either.

answered 22 Apr '20, 15:36

n76's gravatar image

n76
10.8k1082172
accept rate: 17%

Thank you for the quick reply. What do you mean with your last sentence?

(22 Apr '20, 15:43) issibelli
2

the :forward and :reverse tag name suffixes are only needed and used on two way roads. So if travel on the road is restricted to a single direction they are not normally used.

(22 Apr '20, 15:48) n76

Source code available on GitHub .