Yikes, where' can I read the latest numbers from? If this is the case, I'd like to think the range of 24k-30k indicates that the system will initially be operating at a low end of 24k with the ability to have service expanded to service 30k pphpd. Which is still a higher design capacity than Line 1 today. But if they do choose a line with a capacity of 24k-26k that would be a limiting factor in extensions and be rather close to whatever projected ridership they anticipate
The reason I prefer the OL over DRL is the flexibility of the trains used allowed for elevated construction, along with a better alignment+interchanges with other modes. However, I do have 3 criticisms, and one of them is the lack of clarity on whether or not platforms will be expandable for future growth. I don't see a problem using these smaller trains at higher frequency, but allowing for the use of longer trains in the future is good - we don't need to use the TRs like DRL just to get high capacity, if all we need to do is attach more cars to an OL train to match it. ezpz.
In Sydney, the current metro is built for 6-car trains with a capacity of 33k pphpd (2 minute headways). There is provision to extend platforms to accomodate 8-car trains and 45k pphpd. That's pretty high but that's also their primary metro line. If OL uses 5-car 750 passenger trains, the capacity ideally is 30k pphpd. Now, if we roughed in a 40 metre platform extension at the 8 underground stations (this is less than what's roughed in for the Sheppard Line, btw), then we expand its capacity to 42k pphpd with 7 car trains carrying 1050 passengers each. This is all just wishful thinking, I haven't seen anything that suggests they're considering provisions for running longer trains