I think it is likely that the line is an early draft of this boundary:
way/581801454#map=15/53.5607/-2.8513

Looks like some kind of boundary that I dagged with a speed limit by mistake when I was attempting to tag Dicks Lane at the SW end. I certainly didn't draw it, but I might have cut it from a longer line.

The context here is that there is a S-N cycle route (The Sankey Valley Trail) that crosses Liverpool Road at this point. There is refuge some distance to the east:
https://www.google.com/maps/@53.3840854,-2.625147,3a,75y,105.48h,92.61t/data=!3m6!1e1!3m4!1s0lmA7JTsCVLR3oB2gtDv2g!2e0!7i16384!8i8192
so the council recommends that cyclists and pedestrians divert along Liverpool Road, cross at the refuge and walk back. See this sign on the approach from the south:
https://www.google.com/maps/@53.3839888,-2.6254958,3a,27.4y,7.87h,88.13t/data=!3m6!1e1!3m4!1sWBaQ5u80zozL1uCMkcQc8w!2e0!7i13312!8i6656

Of course everybody simply ignores the sign and crosses directly (the council simply doesn't understand pedestrian desire lines) - and certainly cyclists were not going to get off and walk - which used to be the case:
http://wcc.crankfoot.xyz/facility-of-the-month/February2010.htm
so they put up signs to allow cyclists to ride on the pavement from the Sankey Valley Trail to the refuge and back. (though neither the refuge nor the pavement not the refuge are suitable for cycling). The signage refers to this stretch.

Now you can't put the sign in the middle of the road - it either has to be before the cycleway starts (as in this case) or after it starts. In either case it is absurd to map the cycleway from the location of the sign rather than the junction (in one case you end up with a short stub in the other you end up with a disconnected route).

Exactly the same is true for a one-way street meeting a main road. The No Entry signs are not placed on the centre line of the main road, but a shot distance along the one-way side road - but you map the whole side road as one-way - all the way to the junction; not a short stub of two way street as just as far as the sign.

Dismount tradionally is the sign they put at the end of a cycleway to tell you that IT IS NOI LONGER A CYCLEWAY.

It did when I surveyed it just TWO HOURS ago.

I presume you have not coincidently visited Daresbury in intervening period.

The ONLY section of shared pavement is to enable cyclists heading N-S on the Sankey Valley Trail to make a short diversion to the east to cross at the island. (Though neither the pavement or island is is actually suitable).

You can't put the sign in the middle of the road - it has to be one side or the other. It is utterly ridiculous to put a short stub to the west just because the sign is on the west - just as it would be absurd to create a break in the route if the sign happened to be on the other side.

Exactly the same is true for restrictions such as speed limits and no entry signs on side roads. Again the signs of necessity will be offset from the centre line of the main road - but you don't include a short stub of two way road on the grounds that it would be perfectly legal to drive the wrong way up the street just as far as the sign.

I really cannot understand why it is considered in any way controversial or worthy of debate to tag ways where cycling is not allowed as bicycle=no. Certainly having tagged them as such there can be no justification for someone to subsequently go round deleting or changing that tag to anything else.

OSM is a map of the world. A cycle route application designer, possibly based on a different continent, cannot be expected to know the precise rules of who is and who isn't allowed to use any of the menagerie of colloquial names for different crossing types on a small island off the coast of Europe. As with footways "whatever the law is locally" really isn't a very helpful description.

Well google street view is up to date at the southern end and these are the two signs that are visible looking north across Boston Boulevard from the semi-circular cycleway to the south:
https://www.google.com/maps/@53.4002326,-2.6430699,3a,15y,18.36h,90.88t/data=!3m6!1e1!3m4!1s4DK55ObgEpe22bdVrWBMTw!2e0!7i16384!8i8192

https://www.google.com/maps/@53.4004129,-2.6424403,3a,15y,328.49h,93.59t/data=!3m6!1e1!3m4!1sJr87OIKUW6Su3QZCynNuhQ!2e0!7i16384!8i8192

Whereas the semi circular cycleway is clearly signed as such:
https://www.google.com/maps/@53.4004129,-2.6424403,3a,26.3y,176.1h,82.51t/data=!3m6!1e1!3m4!1sJr87OIKUW6Su3QZCynNuhQ!2e0!7i16384!8i8192

At the northern end it is very out of date, but providing photographs of the non-existence of signage is rather tricky.

Not unless the council was out this afternoon putting up signs it isn't

Indeed. The fact remains that the only function of that sort of tactile paving is to give a warning to visually impaired pedestrians. For cycling to be legal on the footway you need blue signs.

Tactile paving is so often deployed incorrectly, I'm not sure how much use it is for the visually impaired, but it has no significance for cyclists.

not on the pavement. you cant. The only signed cycleways are N-S to connect Burtonwood Road. There is tactile paving on the pavement to warn visually impaired people that they are approaching the crossing

You were obviously somewhere else. That always has been and still is the main way in and out of the forge car park.

If a way does not state whether cycling is allowed or not then it is the underlying data that is ambiguous.

However, whether or not you think cycle routing algorithms ought to be able understand that normally riding on the pavement is illegal in the UK, the fact remains that those algorithms exist and are widely used. While I have no control over cycle routing algorithms I can fix the illegal routing problems by the correct the tagging of pavements.

Fortunately, mapping of pavements as separate ways is rare so the confusion does not often arise. It would be helpful if the OSM default was changed to Bicycle=no (and for trunk roads to bicycle=yes)

Unfortunately the default tag is "Bicycle=Not Specified" (exactly the same as for trunk roads where cycling is allowed). This causes problems for cycle routing algorithms which tend to include any ways where cycling in not explicitly forbidden and often actively prefer off-road options. For example this illegal route recommended by cyclosm:
http://brouter.de/brouter-web/#map=19/51.51009/-0.13457/standard&lonlats=-0.134282,51.510237;-0.133601,51.510078&profile=safety.

The tag Bicycles=no is used to express that cycling is not allowed - as is the case on footways in under UK law. Not that possession of a bicycle is prohibited.

Once a cyclist dismounts they become a pedestrian thus access is specified by Foot=*. In the same way, if they strap the bike to the back of a car they can then use motorways.

The summary is more clearly worded:
"A rail, typically metal, designed to keep vehicles within their roadway and prevent dangerous collisions. When mapping, the arrow side of the line points away from the road."

I mapped the Warrington Cycle Network a long while ago and continue to maintain it. This is getting more difficult as people keep breaking it: duplicating sections that are already mapped as tags, deleting sections creating daps in the network and adding cycleways that do not exist on the ground.

Actually it is just a stretch of Burtonwood Road from which motors have been prohibited. So it used to be simply a road with the tag Motor Vehicle = no. Someone changed this to a pedestrian street which isn't quite right.

Nice that the awful barriers have gone - though a bit rich for the council to claim credit for removing obstructions that they installed in the first place and left in place for ten years!

I just corrected the cycle access tag to yes when I noticed the road had disappeared from the cycle map along with the path leading to Burtonwood Road.

According to Sustranns:

https://www.sustrans.org.uk/find-a-route-on-the-national-cycle-network/route-562/

"Route 562 of the National Cycle Network is in development. Once completed it will connect Southport with Aston via Burscough, Wigan, St Helens, Widnes and Runcorn."