05-06-2022, 02:38 PM
(05-05-2022, 03:17 AM)danbrotherston Wrote: I *do* think there is an interesting inversion of thinking that nobody really talks about which is the concept of a double track line with choke points. I'm not sure how this impacts scheduling, but if you widen the track to double tracks everywhere except the most expensive areas (bridges, tunnels, downtown) can you achieve most of the benefit of double track, with a fraction of the cost? Or do you really lose most of the benefits. I'm not really sure, and I don't think anyone can really answer the question definitively without actually studying it, scheduling is another problem that humans aren't very good at (mind you, neither are computers). FWIW...there is a BRT line in Gatineau that uses this concept. It re-uses an old single track railway bridge to cross the...Gatineau? river. Buses arrive and must wait for the bridge to be clear of oncoming traffic before proceeding. FWIW...again, this is something that works better when you aren't sharing with freight trains.
You would likely use a Monte Carlo simulation to study the impacts of the passing tracks in the various areas, along with schedule delays (the likelihood of which should be possible to simulate based on historical data). I absolutely believe that they can determine how much a 2.6 km passing track would help, as compared to a 1.6 km or 3.6 km segment. Not for a particular day, but on average, and with standard deviations.