The “lanes=count” key gives the number of full lanes for motorized traffic. This gives a good estimate for total carrying capacity for vehicle traffic on this road for software that isn’t too concerned about the details, or simply older software that doesn’t know about the :lanes suffix.
If there are keys with the :lanes suffix present, then number of lanes specified by all of them must be the same, and the total number of lanes (including cycle lanes and such) is given by the number of lanes defined in the tags, there is no need to repeat the same number again in the lanes=count tag. If you simply make the lanes=count tag always represent the same number as the lanes specified in the :lanes suffix keys, then you could simply omit it completely, as it’s just redundant. Changing the meaning of the lanes=count tag after many millions of them have already been created makes the key useless as it can’t be relied on anymore. From: Paul Johnson <ba...@ursamundi.org> Sent: Thursday, 10 May 2018 14:56 To: Tag discussion, strategy and related tools <tagging@openstreetmap.org> Subject: Re: [Tagging] tagging of one-way cycle lanes I strongly dispute the suggestion in the wiki in regards to lane tagging as this greatly reduces accuracy for complex lane situations and are NOT analogous to the other excluded situations. The wiki is wrong. On Wed, May 9, 2018, 23:46 <osm.tagg...@thorsten.engler.id.au <mailto:osm.tagg...@thorsten.engler.id.au> > wrote: If I may correct your suggestion, that’s not quite right. To quote the wiki for lanes: The lanes=* key should be used to specify the total number of marked <http://en.wikipedia.org/wiki/en:lanes> lanesof a road. The following lanes should be included: * General purpose <http://en.wikipedia.org/wiki/Lane> traffic lanes suitable for vehicles wider than a motorbike. * <http://en.wikipedia.org/wiki/Bus_lane> Bus lanes, that are reserved for public service vehicles (PSV), for example buses and taxis. Additionally to the total number of lanes, consider to tag the number of lanes for PSV with lanes:psv=*, lanes:bus=* and lanes:taxi=*. * <http://en.wikipedia.org/wiki/High-occupancy_vehicle_lane> High-occupancy vehicle lanes (sometimes also called carpool lanes, commuter lanes, express lanes, transit lanes). The number of such lanes could be tagged using lanes:hov=*. * Other lanes such as <http://en.wikipedia.org/wiki/nl:Spitsstrook> spitsstroken(nl) in the Netherlands or <http://en.wikipedia.org/wiki/de:Stra%C3%9Fenquerschnitt#Seitenstreifen> temporäre Standstreifen(de) in Austria, Germany and Switzerland which are available to traffic at certain restricted times, for example during the rush hour. * Longer slip-roads, for example on motorways and other fast major roads. Turning lanes for minor roads are not normally included. See <https://wiki.openstreetmap.org/wiki/Key:turn> turn=* for further details about tagging turning lanes. And the following lanes should be excluded: * Minor slip roads without a deceleration/acceleration lane, i.e. the main road is wider only because of the intersecting road. * Parking lanes. Consider using <https://wiki.openstreetmap.org/wiki/Key:parking:lane> parking:lane=* to provide further information. * Bicycle lanes. Use the tag <https://wiki.openstreetmap.org/wiki/Key:cycleway> cycleway= <https://wiki.openstreetmap.org/wiki/Tag:cycleway%3Dlane> lane for those. * Emergency <http://en.wikipedia.org/wiki/Shoulder_(road)> shoulder lanes. See <https://wiki.openstreetmap.org/wiki/Key:shoulder> shoulder=* for further details. So a “normal” two way road with cycleways (in Australia, with left hand traffic) would be tagged as: cycleway=lane lanes=2 vehicles:lanes:forward=no|yes vehicles:lanes:backward=no|yes bicycle:lanes:forward=designated|yes bicycle:lanes:backward=designated|yes When tagging to this level, I generally try to also add the width: width:lanes:forward=1|3 width:lanes:backward=1|3 in JOSM the “lane and road attributes” mapstyle will help visualizing these tagged lanes. Use vehicle instead of motor_vehicle (to keep carriages out of your cycle lanes…). Important: Do NOT include the cycleway lanes in the lanes=x count! The lanes count (which only counts marked lanes for motorized traffic) and the number of entries in the :lanes prefix keys can and will be different! (Which is maybe somewhat unfortunate, but the lanes=count tag predates the :lanes prefix tags by many years, and has been used that way all over the place. Mixing different definitions of the lanes key in different places, or even just different segments of the same road, is going to result in useless, unreliable data as a data consumer will have no way to differentiate what definition of lanes=count would apply.) See https://wiki.openstreetmap.org/wiki/Lanes#Crossing_with_a_designated_lane_for_bicycles for an example of that.
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