Low floors also reduce floor space (including narrower aisles)which is less than ideal for capacity on metro type services (and DfT won't pay for the extra vehicles to make up for this loss in capacity).
Fair point! This is the internals of a Greater Anglia class 745 (Stanstead Express).
The different internal floor level also make wheelchair provision a little more tricky, and creates internal steps around sets etc, so it's all a bit of a trade-off.
If you look at the official definition of level boarding - it is just minimal step boarding (e.g. small lips are permitted), the gap fillers don't have to be horizontal they can be angled (as all the HS2 bidders had to do for NR platform infrastructure i.e. everyone but Stadler...). Everyone assumes level = horizontal just because Stadler bid at Greater Anglia in that way. Other OEMs bidding for future contracts may do things differently to what Stadler have done and still comply...
Indeed. The 'official' definition of level boarding would be the values states in the Accessability NTSN:
National Technical Specifications Notices (NTSNs) relating to accessibility (ACC), formerly known as persons with reduced mobility (PRM).
www.gov.uk
This states
Level access
A level access is an access from a platform to the doorway of a rolling stock for
which it can be demonstrated that:
— The gap between the door sill of that doorway (or of the extended bridging
plate of that doorway) and the platform does not exceed 75 mm measured
horizontally and 50 mm measured vertically and
— The rolling stock has no internal step between the door sill and the vestibule.
This definition in itself has no legal or formal standing - it's just a definition. However, it is referenced by the RVAR, which states:
These Regulations set accessibility standards (i.e. standards designed to improve accessibility for disabled persons) for passenger vehicles used on light rail systems (e.g. metro, underground and tramways including prescribed guided transport systems) or which are otherwise not subject to EU...
www.legislation.gov.uk
Boarding devices
1.—(1) Subject to sub-paragraph (2), when a wheelchair-compatible doorway in a rail vehicle is open at a platform at a station, or at a stop, a boarding device must be fitted by the operator between that doorway and the platform, or the stop, if a disabled person in a wheelchair wishes to use that doorway.
(2) Sub-paragraph (1) does not apply where the gap between the edge of the door sill of the wheelchair-compatible doorway and the platform, or stop, is not more than 75 millimetres measured horizontally and not more than 50 millimetres measured vertically.
So essentially, level boarding, or 'level access', is devined as the values below which you don't need to use a boarding ramp, and "passengers of reduced mobility" can "self load".
Is the idea to have new higher platforms only on 4 Relief lines and leave 4 Mains at the old height?
Yes, Old Oak Common will have 8 platforms on the GWML. 4 on the 'Main' lines and 4 on the 'Releif' lines.
The problem is that there's more than one. Historically there was a step up from the platform to the train. It wasn't possible at the time to build trains with lower floors. As a consequence the Heathrow Express only used platforms which were higher than normal. It wasn't possible to rebuild all stations to this standard because it would foul the loading gauge for existing stock, particularly freight.
The Heathrow Express high platform standard was perpetuated in the Elizabeth Line tunnel stations but cannot be applied once out on the older main lines east and west where it shares tracks which have platforms built to older standards.
It's noticeable that the S stock on London Underground has level boarding at many stations. These are full sized trains ofa similar style to the Elizabeth Line but have the advantage that on most of their routes they don't share the plaforms with anything else.
Absolutely. We've baked in historical decisions with the new Liz line, and thus there is a physical incompatability between high floor and low floor trains at the same platform.
The standard UK loading gauge (actually there are lots different ones, but most are different top height, flat or various shapes approximating arches), also has curve in at the lower sides, it doesn't go straight down to axle height.
This means standard 915mm platform heights are at a narrower part of the vehicle, than high floor vehicles (where floor is nearer 1.1m above track level). In slam door era vehicles had wooden step boards and so floor could be at higher level above the frames.
Spot on. Here's a handy diagram showing this.
The 8 surface platforms were originally to be built so any surface trains could call there, and that means with 915mm platforms as there is now plans for many new trains to have a floor section by the doors at this height (even if floor is higher over wheels)
Indeed. This is the standard soliution, but with the platforms forming the connection between the Elizabeth Line, which is level boarding in the central section, and HS2, which will be level boarding throughout, it makes a lot of sense to break with convention here.
This does not mean that staff are readily available where you need them. The sentence you’re replying to made perfect sense and this doesn’t as a response to it imo.
Very true! Old Oak Common will very much be staffed first to last, but yes, you can put loads of staff onto a station but there will always be a time when they are int he wrong place!
