Whilst that's true, the other factor to consider is that future rail use also isn't what it currently is and whilst rail use on the SWT network has been generally falling between 2016 and 2019 there is an argument that the network was at the limit of use at that time (at least in the peak hours, but with any significant failure taking a long time to recover).
Future use is always going to be hard to predict, however with the strikes looking like they are going to be stopping as part deals get sorted there's a fair chance that in the sort term we continue to see growth.
What that looks like is harder to predict, however based on the rolling average 12 month total increasing by between 1.3% and 4% over the last 6 quarters (with around 2.7% being fairly typical when you average across those 6) if we assume the next 6 quarters the rolling annual total grows at 2% then we'll see quarterly use for SWR of between 40 and 44 million each quarter.
If that trend continues longer term (which is unlikely, but given I've assumed a lot than average from the last 6 quarters, it could continue for longer than the next 6) then we could see the equivalent of 2016 use in around 2029.
Even if the average growth fails to 1%, then we still reach 2016 in about 2035. Although that is still far from certain, although there were several quarters in 2013-2016 when there was this 1% per quarter in the rolling annual growth, so with higher than 1% in the early years it's not impossible to see some fluctuations and still reach those sorts of numbers over that timeframe.
The problem is, that by the time we can be sure that those numbers are happening it's almost too late to start building to provide the capacity as it'll take time to deliver the scheme.
That's not to say that we should start building it now, however there should be a point (which isn't now now, however it also isn't when the annual use for SWT is 230 million) when we should start the process towards building it and another pint in time when we actually start building it.
That time may never happen (or even the first may happen but the point to build it not ever happen), but likewise both points could happen within the next 15 years.
For example if the get on with work short of starting building works when we hit 170 million and growing (current annual use is 153) and start building when we reach 200 and growing (as 2019 was 203 million and falling) then on the 1% growth numbers we'd be doing so in 2026 and 2030, with the trend showing that by 2042 (with enough capacity, which there wouldn't likely to be without Crossrail 2) that rail use could exceed 300 million a year.
Even being in a position to start building as we reach the similar numbers seen in 2019 (if passenger use is still growing) could, arguably, be starting too late.
Based on 2% growth then these are the next 6 quarters of rail use for SWT:
April - June 2024 41.2 million
July - September 2024 40.1 million
October - December 2024 42.6 million
January - March 2025 42.0 million
April - June 2025 44.5 million
July - September 2025 43.5 million
Likewise at 2.5% growth then it's:
April - June 2024 42.0 million
July - September 2024 40.9 million
October - December 2024 43.4 million
January - March 2025 42.8 million
April - June 2025 46.2 million
July - September 2025 45.3 million
It'll be interesting to see what the actual numbers are, higher than those (and not just one but all of them higher, so no getting too excited if we see 42.1 million for the next quarter) and we'll likely need to look at Crossrail 2 sooner than some think, much lower than the 1% numbers (see below) and it may not be on the cards for some time (if ever) because percentage growth in the next 6 quarters is likely to be higher than the 6 quarters of growth starting in (say) 2030 (even if the extra number of people each quarter is higher at that point).
Based on 1% growth then these are the next 6 quarters of rail use for SWT:
April - June 2024 39.7 million
July - September 2024 37.0 million
October - December 2024 37.8 million
January - March 2025 35.6 million
April - June 2025 36.4 million
July - September 2025 33.6 million
It's worth noting that in 2019 there were 52 million to 55 million per quarter, so whilst those would still be a significant way short of that, the point is we probably don't want to wait until we are actually seeing those numbers if rail use on the SWT network is growing (if takes 20 years to get to that point then there's not too much of a rush to do much as it could take another decade to get close to the 2016 numbers). What we need to see is what is the trend showing and even then we'll probably actually need to see data from 2027 (at least) to be sure that it's not just flushing through the impact of Covid and the strikes and even then it maybe at least 5 more years of data to be sure that we want to start building.
Obviously, SWT use is only one factor, however it's something which is easy to monitor.