The topography of Sydney hasn't changed and the original surveys of
streets showing street gradients for the tramways are still available. 
Some, including George Street, are even shown in Keenan's books.

The original tramway engineers, including Dr John Bradfield, developed
and published in the public domain a suite of tramway system standards
including, of course, the design specified standard for system trams. 
As Tony notes Sydney had lots of hills.  The Sydney trams moved quite
swiftly along 'hills' such as Bondi Road, "Heartbreak Hill" (as it is
referred to in the City to Surf Fun Run) on the Watsons Bay line,
Circular Quay to Elizabeth Street (too steep for steam trams) and
numerous other locations.

Greg

On 8/07/2019 8:01 am, Prescott wrote:
> Thank you Mark for expressing the situation perfectly. Back the 20th

> century Sydney had a big system with lots of hills in it and smaller

> trams with only two bogies per tram, so having all wheels powered was

> necessary. Today the tramcars have three or four bogies per car which

> makes them more expensive to manufacture and more bogies powered makes

> it even more expensive. So they try to get by with a minimum number of

> powered bogies, unless a system has a lot of steep hills to deal with

> (e.g. Prague) when they don't have a choice. If there is only one

> excessive grade in the whole system then the design engineers will

> look at ways of reducing or bypassing that grade in order not to have

> an entire fleet that is up-specfied just to deal with that single grade.

>

> Tony P

>