When a B-Road becomes semi-declassified, how do we know its new extent? Is there an online database of B-Roads somewhere? Or is it just that road signs get removed?
It's not road signs. Hardly any B Roads in London are signposted with their B Road number, either on the approach or along the road itself. Things are different elsewhere in the country where a B Road may be the most significant route for miles and copiously signed. But just checking signs is no great help.
Instead yes, there's a database and it's called the National Street Gazetteer. Local authorities upload data monthly, for example if a new road is built, and are also supposed to keep track of any changes to road classification. The gazetteer is co-ordinated by GeoPlace, a collaboration between the Local Government Association and the Ordnance Survey, and currently contains 1,486,432 streets each with their own Unique Street Reference Number (USRN). It's been freely accessible since July 2020, although the download's so huge my laptop hasn't been able to cope with interpreting it.
Instead the best place for a specific search is www.findmystreet.co.uk/map where you can zoom in on a specific road to discover its USRN, its classification and who's responsible for it. For example the map confirms that Bow Road (22700175) is an A Road maintained by TfL and Old Ford Road (22700893) is a B Road maintained by Tower Hamlets. One catch is that the data isn't necessarily 100% up-to-date - for example it shows Sweetwater Place in the Olympic Park as Under Construction even though it's been open to traffic since April. Another drawback is that the pop-up box doesn't explicitly state which B Road a road is, only that it is one. [alternative map]
Meanwhile road classification has been the sole responsibility of individual local authorities since April 2012 when the Department for Transport relinquished control. You can read their comprehensive list of guidance on road classification and the primary route network here. Only when creating a new A or B Road does an authority need to contact the department to obtain an unused number from a centrally-kept list. Similarly the department likes to know when road numbers are retired so that, after a suitable pause, they can be reused.
I said yesterday that half the B118 appeared to have been declassified. I based this on OpenStreetMap no longer showing Columbia Road, Gossett Street and Old Bethnal Green Road in yellow, and the impossibility of driving down this end of the road due to due to traffic calming measures. However the map on findmystreet.co.uk indicates that all three of these streets are still very much part of a B Road, which the OS map underneath confirms is still the B118. No matter that you can now only ride it on a bike, it's still officially a B Road because Tower Hamlets council has never uploaded any changes to say otherwise.
My apologies to residents of Columbia Road, Gossett Street and Old Bethnal Green Road because they got very short shrift in my B118 write-up. Nevertheless I did actually walk the whole thing and you got twice as much detail about half as much road. I believe I've blogged the correct length for all the other B Roads I walked before that.
However I remain conflicted by the B116 which I don't think exists but various mapping platforms are convinced is in Plaistow.
The road in question is Balaam Street which links The Broadway (A112) to Barking Road (A124). It's definitely a B Road because findmystreet.co.uk says so, and the underlying OS map says it's the B116. Open StreetMap agrees, as snapped top left. But StreetMap (based on Bartholomew mapping) is convinced it's the B166, as is my 2000-vintage London A-Z, as was the Ordnance Survey in 1966, as is the SABRE website, as is whoever compiled the legislation for the 2012 Olympic Route Network. It definitely started out as the B166 because that's what the 1923 road map top right shows, and the B164, B165 and B167 are suspiciously close by.
B Roads do sometimes change their number, and the original B116 over by Victoria Park died early, but I don't believe the classification's been transferred to a road in Plaistow which already had a perfectly good number.
"It is possible that the sequence of events which led to it being recorded in the National Street Gazetteer as the B116 were faulty. That's not unknown - there are other instances where data was wrongly transcribed when copying from original paper records into digital records. In this case, it's easy to see how B116 could be a typo for B166.
However, the NSG is considered definitive even if the process by which a record was added to it was faulty. So there is no dispute that the street *is*, now, the B116. The fact that it may, once, have been the B166, and the change was the result of a fat-fingered data entry clerk, does not mean that it is still the B166."
It seems Britain does have an official list of B Roads but it's only as good as the information pumped into it and this may not have been accurate before 2012 in the first place. The data's not especially public either, which means the best place to look is probably a map, or else the excellent SABRE website, but even those aren't necessarily 100% correct. It's unlikely ever to bother you, but it's not as tidy as you unconsciously assumed it was.