I noticed that default maxspeed for routing is given in "OSM tags for routing/Maxspeed" but the country I live in, Sri Lanka, is not listed. How can I include Sri Lankan default maxspeed values?

The default values are given in Government Gazette of Sri Lanka. The official value for motorcars is 70 Kmph. But, actual average driving speed can be lesser than this for secondary and tertiary roads.

I did search for similar question, but did not find the answer I look for. The best I found was this, but it did not tell me how exactly I can get this done. Help me. I’m new to OSM.

Thanks

asked 25 Jun '13, 08:45

Himal's gravatar image

Himal
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accept rate: 0%


Just edit the mentioned wiki page and add Sri Lanka to the list. These values are just for documentation. They don't automatically affect any router and are not imported into OSM's database. Still they can be helpful for anyone writing or updating a routing engine so it is a good idea to extend this list and keep it up-to-date.

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answered 25 Jun '13, 08:52

scai's gravatar image

scai ♦
31.1k18281434
accept rate: 23%

Thanks; by the way isn't it possible to include maxspeed to highway types within admin boundary of Sri Lanka so that it will be effective for roads without maxspeed tag?

(25 Jun '13, 09:09) Himal
2

@Himal Of course this is possible. But this decision should always be left to the end-user application. A router will have to assume some value for roads without a maxspeed tag and this wiki page could be one of the possible sources.

(25 Jun '13, 09:44) scai ♦

@scai Thank you for all information and advice.

(26 Jun '13, 06:02) Himal

Generally speaking, it's a bad idea to add a "maxspeed" value to a road that's not been surveyed as it will only cause confusion, as it has in the past when it's been done in Australia and (to a limited extent) the UK.

What will happen is that people will assume that "maxspeed=70" on a road means that someone's been there and checked that the maxspeed is in fact 70, when it might be some lower value.

Routers in Sri Lanka ought to know what the default local maxspeed is; if they don't they're not suitable for use there.

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answered 25 Jun '13, 09:30

SomeoneElse's gravatar image

SomeoneElse ♦
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accept rate: 15%

I got your point. Thanks.

But my problem was OSMAnd counts incredibly higher speeds to trunk roads avoiding certain secondary roads in the rout, which would in fact have been faster route in reality. In my experience, average practical max speeds for trunk 70, primary 60 and secondary and tertiary 50. Can this be set somewhere?

(25 Jun '13, 09:45) Himal
2

Very probably. I'd try asking the osmand folks over here. If all else fails, the source code is here(!) - it's actually quite straightforward to build if you need to.

(25 Jun '13, 09:56) SomeoneElse ♦

@SomeoneElse Thanks a lot.=)

(26 Jun '13, 06:03) Himal

Add the speed on the road with maxspeed=* and then add source:maxspeed=lk:urban for default speeds in urban areas, and source:maxspeed=lk:rural for default in rural areas. That way if the default speed changes, you can find where you have to change those speeds.

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answered 27 Jun '13, 11:32

Janjko's gravatar image

Janjko
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accept rate: 0%

2

One important caveat - I'd only do that if I'd surveyed the road in question and know that that really is the maximum speed of the road in question (i.e. that there isn't another, lower, local maxspeed for some reason).

Adding unsurveyed data to the database adds no new value and devalues what's already in there.

(27 Jun '13, 11:47) SomeoneElse ♦
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question asked: 25 Jun '13, 08:45

question was seen: 2,682 times

last updated: 27 Jun '13, 11:47

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