Re: [NSW] Cityrail Grades

[Ben Armstrong <ba13@uow.edu.au>]

On Wed, 12 Apr 2000, Anita Lukaszyk wrote:

> I *think* it uses 'feet' instead of metres.

It doesn't matter what units you use. It's the ratio that's the
important bit. 

> Please dont use TAN. It reminds me too much of Year 10 maths!  :) That bloody SOHCAHTOA thing...
> AAAARGH!

Have to agree with you there!

> Hubert Lam wrote:
> 
> > Sorry does "1 in 40" mean tan x = 1/40 (rises 1 metre vertically for every 40 metres of horizontal
> > track) or does it have some other meaning?

Yeah- Rise over Run.(you see- geograpghy is useful!) I'm not sure
whether they would use sine instead of tan though. (top bit of the
triangle) Wouldn't be that much difference anyway.

Another thing that has to be taken into account when talking grades is
whether the grade quoted is compensated for track curvature or not.

Say that a bit of curved track is said to have a 1 in 30 compensated 
grade on it. The track itself may only have a grade of say 1 in 35, but
it is 'rated' at 1 in 30 to allow for the extra rolling resistance
through the corner. (so that enough HP is put at the front of the train
to get everyone home happily) :-) 

Hope this helps,

---
                           ______________________________________
Ben Armstrong                                         /
                               _______________________\___   ______
<ben.armstrong@boral.com.au>  /  ___  |_||_||_||_|  _ _   |_|  ___ 
<ratso_101@hotmail.com>      //|| | |    Ratsara   | | |  | | | | |
<ba13@uow.edu.au>           //_||_|_| |_||_||_||_| |_|_|  |_| |_|_|
                           /______________________________| |______
ICQ #: 1434 3878                 0-0                0-0        0-0