|Realistic speed estimate in cases where official speed limits are meaningless and speed information can not be estimated in other ways.|
|Used on these elements|
|Status: In use|
|Tools for this tag|
Map realistic speed estimate in cases where official speed limits are meaningless and speed information can not be estimated in other ways.
Some mappers object that the use of maxspeed:practical violates the principle of verifiability, and is used for lack of a better alternative such as live traffic data. It is not an example of good practice, and should not serve as an argument for the introduction of similar keys.
How to map
maxspeed:practical can be used to map a "realistic average speed" on highways where other tags are not sufficient to describe what kind of traveling speed could be reasonably expected.
It could be used especially where there are no speed limits or the difference between posted maximum or advisory speed to realistic speed is particularly large. Many mountain or rural roads as well as desert tracks do not have posted speed limits or the realistic traveling speed may be severely limited by factors difficult to describe and difficult to use for calculation by routing software.
- maxspeed:practical=15 - you can expect to drive around 15km/h
Use with conditions
Conditional restrictions could be used such as:
- maxspeed:practical:conditional=30 @ (07:00-09:00); 40 @ (16:00-19:00) + maxspeed:practical=60
- maxspeed:practical:hgv:conditional=20 @ (07:00-09:00); 30 @ (16:00-19:00) + maxspeed:practical:hgv=50
- maxspeed:practical:conditional=30 @ wet - expect an average speed of 30 when wet
Data consumers may not support this for some time so it is important to specify a fallback.
Expected evaluation by routing software is to apply the most specific matching value of maxspeed:practical and if none matches fall back to the most specific values of maxspeed:advisory=* and maxspeed=* as described here: Conditional_restrictions#Evaluation_of_conflicting_restrictions. Hence there is no use to specify maxspeed:practical in conditions where maxspeed or maxspeed:advisory are sufficient.
Old style conditions
This syntax was developed before the approval of Conditional restrictions and in theory may be still evaluated by some data consumers but none is known.
- maxspeed:practical=90;nighttime:70 - you can expect to drive around 90 km/h at daytime, 70 km/h during night hours.
- maxspeed:practical=60;rushhour:20 - 60 km/h at all times except rush hour.
- Conditional restrictions - should use this notation as far as possible
- Average speed per way - other thoughts how it could be done, unfortunately defunct
- Proposed features/traffic speed - fairly similar proposal
- Global Statistical Speed Matrix - another work in progress concept of speed data storage