Gradient question

[Concrete_Bob]

I'm working on some route features based on a local line. How do I convert local gradient terminology [i.e. 1:50} into the scale used in surveyor?

 

[grazlash]

1:200 0.5%, 1:100 1%, 1:50 2% and so on

 

[Concrete_Bob]

1:200 0.5%, 1:100 1%, 1:50 2% and so on

Thanks. Presuming then that the height value on the track [advanced] tab is the percentages? A 1:33 Grade would be 3.0 on the surveyor tool? [Otira Tunnel, NZ]

 

[Bill69]

Thanks. Presuming then that the height value on the track [advanced] tab is the percentages? A 1:33 Grade would be 3.0 on the surveyor tool? [Otira Tunnel, NZ]

That is exactly what grade is in the Otira Tunnel and it's 8.5 kilometers long. So if you are doing a prototypical route of the west Coast that is what you should be using. Steam locos are not allowed in the tunnel unless they are under light steam i.e. being towed by electric locos.

Cheers,
Bill69

 

[Alikiwi]

Get the "Optical-Grade-Chart" which you can probably google, as I did. Hm, not sure how I found it. Same source but a not as neat pdf, https://surveyequipment.com/assets/index/download/id/101/

If it doesn't like the link, the source is surveyequipment dot com.

 

[Concrete_Bob]

That is exactly what grade is in the Otira Tunnel and it's 8.5 kilometers long. So if you are doing a prototypical route of the west Coast that is what you should be using. Steam locos are not allowed in the tunnel unless they are under light steam i.e. being towed by electric locos.

Cheers,
Bill69

No electrics on the midland line, DX diesels , with an extra 4 bankers on the tunnel gradient.

 

[Concrete_Bob]

Awesome help thanks. Not going full prototypical, just looking at the tunnel as a benchmark for extreme gradient scenarios.

 

[Bill69]

No electrics on the midland line, DX diesels , with an extra 4 bankers on the tunnel gradient.

Ah! You are right, the electrics were removed about eight or nine years ago.

Cheers,
Bill69

 

[Concrete_Bob]

Some really cool reading about the tunnel - Apparently, around 80 tonnes of sand is dropped in the tunnel every year.

http://www.rmtunion.org.nz/publications/documents/OtiraTunnelReport-Final.pdf

 

[llebrez]

Having read most of the documentation provided on the Otira tunnel, I just have the following comment or question: Who's brilliant idea was to eliminate electric traction at this line? Money? Looks like diesel on the long run is way most costly. Or the diesel loco salesman was pushing his products above common sense.

 

[Concrete_Bob]

It was a 10 km section of electrification on a 212 km line, put in place specifically to resolve the issue of excessive smoke from steam locomotives in the tunnel. The last electric locos were purchased in 1968. By 1988, increased volumes of coal freight and larger consists meant that there were not enough units in service at any time to haul a full coal train up the incline. Switching to diesel bankers meant that the two locos used on the eastern side of the tunnel could remain coupled and continue the western side, and vice versa.

 

[JCitron]

It was a 10 km section of electrification on a 212 km line, put in place specifically to resolve the issue of excessive smoke from steam locomotives in the tunnel. The last electric locos were purchased in 1968. By 1988, increased volumes of coal freight and larger consists meant that there were not enough units in service at any time to haul a full coal train up the incline. Switching to diesel bankers meant that the two locos used on the eastern side of the tunnel could remain coupled and continue the western side, and vice versa.

This sounds just like the Hoosac Tunnel. it was electrified in 1910 and the wires came down in 1946 and put in for exactly the same reason. This was the only electric section on the Boston and Maine and by the time the diesels came along that were worthy, the ca. 1910-1911 electrics were a bit worn out. A new set of EMD FT-units put the electrics on the scrap line.

Getting back to topic. This is rise over run, the same as working out slope in geometry. My driveway works out to be about 12.5% and I don't leave the house in snowy weather!

 

[MP242]

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