Who says tight curves are only for modelling?

[TrinityJayOne]

We all know the saying "there's a prototype for everything", and here's some proof that it's not just our model railways that have sharp turns.



I took this on my commute home today from the first of a 6 car suburban EMU. This is the sharpest railway curve in Melbourne, and funnily enough is followed shortly afterwards by a not-so-sharp curve in the opposite direction (not shown here). Why? Couldn't it have just been a gentle S-curve instead? Well, *puts on history-teaching hat* this tight curve used to form part of a triangular junction where another steam-era railway line splintered off in another direction. Said line has long since been removed, but a few remnants remain such as rails left in the asphault at old crossing sites (which must confuse the hell out of non-railbuffs/locals ). Here's a Google Earth view of the curve-



At some point it was electrified, and circled at the top are some remaining gantries from the northern leg of the junction. Circled at the bottom is a gantry that has its left leg much further away from the tracks than the other gantries, assumedly because this is where the southern leg split off from the main.

As you can see from the video, the curve isn't exactly the smoothest section of track in the world. The intermittent jumps of the camera are due to the tiny bits of straight section required at the rail joins (look carefully and you can see them on the parallel track). Yes, making smooth mid-corner joins is apparently difficult in the prototype as well!

[LoudMusic]

Your example is a bit more profound (and well described) since it's mainline, but here's an example that's been discussed before on this forum I believe.

http://goo.gl/rGCgQ

That's a google sat map of a rail to ship exchange facility in Portland, Oregon. Someone has done the math before and apparently it comes to HO scale 18" radius. I haven't verified this, but I bet it's pretty close.

[JazzDad]

Are there squeals of flanges to be heard in the background of that video?

[Iron Horseman]

Using the automobiles in the picture as a scale, that inside curve would be what in HO, about 50" radius?

[TrinityJayOne]

Yes JazzDad, plenty of it. I've read somewhere before that these trains don't have conical wheels, rather they rely on cant in corners to reduce wear.

[bradyracing]

That is not tight at all. The railroads know what they are doing.

[LoudMusic]

I used the satellite images from Google Maps and came up with real radius of 378.8' and HO scale radius of 52.2".

I'm happy to share my work if anyone is interested but won't bother you with it unless asked.

[TrinityJayOne]

I was going to give it a shot but I'd probably fail at it, so thanks.

[PaulB]

Originally Posted by LoudMusic

I used the satellite images from Google Maps and came up with real radius of 378.8' and HO scale radius of 52.2".

I'm happy to share my work if anyone is interested but won't bother you with it unless asked.

OK, so a chain is 66 feet. That would make this curve about 5.7 chains? That is a tight curve by most reconing. The state north of Victoria is New South Wales. Their tight curves on mainlines were 8 chains. Some branch lines had 5 chain curves but with guardrails inside the outer rail.

There is a tight curve leading from Bowen Hills station (Brisbane Qld) into the yard. I make that out to be around 300' radius, so maybe 4.5 chains?

http://maps.google.com.au/maps?rls=c...&ved=0CMEBELYD

[bcp]

That's a google sat map of a rail to ship exchange facility in Portland, Oregon. Someone has done the math before and apparently it comes to HO scale 18" radius. I haven't verified this, but I bet it's pretty close.

Measured on Google Maps