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Drivers have various needs to overtake slower vehicles. On a previously unknown road waiting for a section of the road with sufficiently long lines of sight and without overtaking restrictions, can be unnerving or tiring: one should have enough speed differential already when making the decision on whether to overtake.

The greater the speed difference, the less time spent on the lane of opposing traffic (naturally taking the locally accepted and allowed speeds into account). With a less powerful car it is beneficial to accelerate for overtaking already before the line of sight for safe overtaking appears. Then the driver can decide whether to abort or go.

What to consider when assessing overtaking safety:

  • No passing -signs or road markings
  • Dedicated overtaking lane
  • None or minor (yards only) junctions
  • Directionality: a straight or a slowly curving bend might be good for overtaking in one direction only.
  • Speed limit vs. length of the line of sight (hills, forests, bushes, bends)
    • In low speed limit areas overtaking is seldom restricted by line of sight but more by the amount of oncoming traffic and width of the road; those areas wouldn't need these relations.

In ideal world these could be derived from other saved information. On faster but winding 1+1 lane countryside roads good places are less common and marking especially these would be the intended use.

Ultimately assessing overtaking safety is the driver's duty, but with this information a navigation system could give auditory signals of possible overtaking places ahead, if requested, and give information on the expected time and length of free lane required for the overtake.

As the end of safe or allowed overtaking section is marked, auditory warning not to start overtaking could be given when it is unlikely that the car could complete the overtake before that location, given it's speed and position.


Key Value Discussion
type overtaking
overtaking lane/straight/bend Optional. The way ought to be split anyways, where a two lane road becomes three lanes for the overtaking lane.


Way or Node Role Recurrence? Discussion
Node from one Start of possible overtaking section. Usually start of the line of sight, too. Should be part of any of the ways in the role 'road'.
Node to one End of safe or allowed overtaking section. By this node the driver should be back on his own lane. Ought be part of any of the ways in the role 'road'. From this node should be a line of sight of at least 6 seconds.
Node fromLatest optionally one Last possible start for overtaking.
Node fromSight optionally one Start of the line of sight. Possible when line of sight starts before signed or implied overtaking restriction end.
Node toSight optionally one End of the known line of sight. Must be further along the than the node in role 'to'. If not present, software can calculate this based on location the node 'to', speed limit and own speed. (speed 1 + speed 2) * 4 seconds.
Way road one or more ways making up the road, on which the described possible overtaking section is.


Please use Talk:Relations/Proposed/Overtaking.