On 16 March 2011 17:38, Colin Smale <colin.sm...@xs4all.nl> wrote: > On 16/03/2011 18:00, Peter Miller wrote: > >> >> My understanding is that the signed speed limits are those that must be >> obeyed by those classes of vehicles that are not limited by some other rule. >> I don't consider that we need to do more that we are which is to reflect the >> street sign in the data. >> > It'll be the lower of the signed speed limit and the limit for the vehicle > class. > > IIRC the "national speed limit" is 30mph in a "built-up area" (i.e. even if > there is no speed limit sign) which is defined based on the distance between > the street lights. Assuming this still applies, you can't infer that the > effective speed limit on a single-carriageway road segment is 60mph unless > you have been out with your trundle wheel and plotted all the street lights.
This rule goes back to 1934 when speed limits were re-introduced and the government didn't want to wait for signs to be installed at every transition from rural to town (and couldn't afford to do so). Incidentally, the need for street lighting in towns seems to have been provide by the 1875 Public Heath Act http://www.bbc.co.uk/scotland/learning/bitesize/standard/history/1830_1930/public_health_rev3.shtml Are there still examples of roads where there is no sign (other than indirectly provided by the presence of street lighting) to indicate that one is entering a 30 mph zone? I can't help feeling that in the past 87 years that signs will have been placed in most if not all of these places if only because they are likely to be very much more effective than a row of lamp posts at getting people to slow down! This article has useful definitions of built-up area and talks about the rules for repeater signs, but makes no mention of the initial signs. http://en.wikipedia.org/wiki/Built-up_area_%28Highway_Code%29 Regards, Peter > > > > > _______________________________________________ > Talk-GB mailing list > Talk-GB@openstreetmap.org > http://lists.openstreetmap.org/listinfo/talk-gb >
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