Expanding on my previous post....
Mt Barker - Bridgewater - Adelaide Express Route Proposal
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The SA government probably doesn't have enough $$$$. I am dreaming.
However this is a relatively cheap way to reduce train travel times by 21 minutes between Bridgewater and Adelaide station.
Realignment starts at Bridgewater towards Adelaide - ease the curves to Heathfield.
Then 900m tunnel (under Heathfield Netball club) and follow the Sturt River at 1/40 gradient.
At one point rail line will cross river - bridge approx 300m long.
Line goes through northern part of Blackwood Forest Recreation Park, altitude of 240m.
Then long bridge (approx 700m) across Minno Creek.
Then rejoin existing line at Coromandel (altitude approx 240m).
This express route can have track speed of 115km/h, so overall average speed is 100km/h.
Existing line
Coromandel 17.2km from Adelaide
Bridgewater 37.6 kilometres from Adelaide
20.4km at 40km/h = 30.6 minutes
Express line
14.9km at 100km/h = 9 minutes
Saving 21.6 minutes
Quoting from another Railpage thread:
Back in 1979, when dinosaurs ruled the earth, I was a regular train traveller - Heathfield to Mitcham or Adelaide. Back then, 218 would do the trip from Bridgewater to Adelaide in 58 minutes (all to Eden Hills, then Mitcham and Adelaide).
The new Express Route would allow trains to go Bridgewater - Adelaide in 37 minutes.
I believe Mt Barker Station is 55km from Adelaide Station.
(55km - 37.6km) @ 50km/h average speed = 21 minutes
Total time Adelaide - Mount Barker is 58 minutes.
The existing express bus is 55 minutes.
The new express rail line may possibly be justified if the existing bus service is completely inadequate, e.g. there are huge number of commuters trying to catch those express buses.