Re: Re: Tram and light rail gradients in Sydney.
  TP

Bear in mind that Sydney's initial 19th century tramways were designed for
steam trams, which were not too good on hills, so the gradients were quite
gentle. That prevented them accessing localities like Circular Quay and
Neutral Bay and it was only with the advent of electric trams with 100%
adhesion that they were able to extend to such places. Sydney's new light
rail trams have only about 66% adhesion, so their ability to tackle grades
is not as good as the old trams. Modern trams can be built with 100%
adhesion, but the decision was made not to choose that option for Sydney.
All of the modern lines in NSW traverse pretty unchallenging landscapes, so
it's not a big issue - except for Central Station.

These trams with 66% adhesion have a gradient limit of about 6% (about
1:16). So Hunslet tells us that the grades at Central are 1:15.61 and
1:18.4. My guess is that the eastern ramp, being slightly longer, is the
gentler 1:18 grade and the western ramp is steeper at 1:15. So the CAFs and
Citadis would be able to tackle the eastern ramp OK and the western ramp is
in the descending direction, so that's just a matter for the braking rather
than climbing ability. If the directions were reversed, they might struggle
a bit climbing the western ramp. The western ramp would be the prevailing
grade on the Sydney lines.

Tony P

On Tuesday 9 July 2024 at 13:48:26 UTC+10 David Batho wrote:

> Aah. Missed ‘adhesion only’!

>

> David

>

> Sent from my iPhone

>

> On 9 Jul 2024, at 11:15 AM,billbolt...@... billbolt...@...>

> wrote:

>

> 

>

> <IMG_0125.jpeg>

> On Tuesday 9 July 2024 at 10:11:54 UTC+10 Hunslet wrote:

>

> Doubtless discussed previously, but what were the steepest adhesion-only

> grades on the former Sydney tramway system

>

> The steepest adhesion only grade was at Hayes St in Neutral Bay which

> was 1 in 10 down to the wharf jetty, and required trams with additional

> braking systems.

>

> There were a number of 1 in 11 and 1 in 12 grades, notably on the Watson's

> Bay line and on the Young St loop at the Circular Quay end of the Elizabeth

> St routes. All the steep grades were traversed at very low speeds.

>

> The Darling St Wharf grade was not adhesion only, as there was cable

> connected counterweight assistance.

>

>

>

> --

> You received this message because you are subscribed to the Google Groups

> "TramsDownUnder" group.

> To unsubscribe from this group and stop receiving emails from it, send an

> email totramsdownunde...@....

> To view this discussion on the web visit

> https://groups.google.com/d/msgid/tramsdownunder/ac171f18-ec0c-4b1c-9429-3132c0d4f773n%40googlegroups.com

> https://groups.google.com/d/msgid/tramsdownunder/ac171f18-ec0c-4b1c-9429-3132c0d4f773n%40googlegroups.com?utm_medium=email&utm_source=footer

> .

>

> <IMG_0125.jpeg>

>

>