This changeset has two problems:
1. you have blocked off platform 3
2. access=no is not right here, since this bridge is accessible when trains do call at platforms 1&2. This has resulted in my journey planner not able to produce the correct route when a train calls at platform 2.

The bare ref= should contain the primary reference value as used by the operator itself. The CRS code should only be listed in ref= if it is actually a National Rail station, as London Underground or any other networks have their reference codes.

These CRS codes are all valid and in use, which should not be removed.

I have no idea, it was just the result of merging duplicate objects.

https://tfl.gov.uk/cdn/static/cms/documents/rfliccostpr2026v1.pdf

The timetable planning rules clearly lists the operational CRS codes for all the Elizabeth line CCOS stations - CRS codes exist for stations and also other places like depots, junctions, as seen in Network Rail data (which is open data), so the use of ref:crs is appropriate.

ORR derives the stations usage statistics from ticketing data, which do not separate PAD/PDX, STP/SPL, ZFD/FDX, LST/LSX, etc., because they are considered the same station in terms of rail ticketing, but operationally they are clearly two different stations (apart from Farringdon which is disputable) which can be easily verified as ground truth.

LSX is the code used in the timetable data for the Elizabeth line station, this code can be found in the Network Rail data under the column crs_reference_code but it is not publicised.

Similarly for PDX (Paddington Crossrail), FDX (Farringdon Crossrail), SPL (St Pancras Low Level), etc. The existence of separate codes, along with separate entrances / concourses / gatelines or even operators for ground truth both confirm that they are two physical stations for operational purposes.

The ground truth disagrees with the ORR.

Can you please don't make any edits which do not correspond to the ground truth?

The Network Rail and Elizabeth line stations at Liverpool Street are clearly separate by any verifiable means on the ground, even in the Elizabeth line route diagrams and timetables. They are just treated as one for ticketing purposes.

https://community.openstreetmap.org/t/how-to-tag-spiral-staircases/127529/6

Self intersection of spiral staircases is not a problem (although I have to add the missing tags - I ran out of time when surveying the station)

My understanding of the road network is that MOS road is a fork from T7. The distance markers count consecutively from Ma On Shan Road upon leaving route 2, through the Ma On Shan Bypass and onto the Sai Sha Road. Similarly on the other end, Sai Sha Road into the town centre is a westbound fork from the T7 as well.

In terms of the road network, isn't the bypass the main one, and the MOS to Road a fork from it? Only consider using the current network without taking any history into consideration please.

Sorry, you have messed up the underground station. I see that you added nodes onto the underground structure which shouldn't be connected to the street.

Paths inside train stations shouldn't be tagged with access=destination

Such usage will prevent OpenTripPlanner to use it on a through journey after alighting the train at Derby as the station is not the destination, just a place to change trains.

I have just fixed the relations and added some mapped platforms, please check.

Hello, please don't blame me on it. The relation was wrong well before I surveyed the stations en route, including the placement of stops on the opposite direction, and such fixes couldn't be done locally.

Sorry I've just missed it

Anyway I have just retagged Stratford with linear ways and indoor=area

I will do it later with London Bridge but without linear ways (as it is impossible there) to see what it will happen.

I have just surveyed London Bridge as well and, given how the station looks like, it is impossible to map the National Rail ground level by anything but just slap two areas (paid and unpaid) into it.

I'm currently working with OpenTripPlanner with area handling enabled, with the aim that accurate and realistic information can be delivered to people how long it takes and how to access platforms for train services.

Even if a router doesn't support areas, it will still route along the edge of these areas.