Sydney was pretty-much done with new single truck trams in the first decade
of electrics, but in an environment of huge growth, needing as many trams
as they could get, the four-wheelers ran on for years by default. Getting
rid of 200 E class because they were out of date and couldn't be replaced
fast enough, for example, would have been crippling to the operation. I bet
there was a lot of extra track maintenance associated with them - just the
yawing on its own, never mind curves.

There is a compromise modern solution. Since the leading truck, that hits
the curve first, is the most critical one, some tram models have only the
end bogies swiveling and the rest are fixed under short modules, not much
longer than the truck itself, creating an ersatz swiveling bogie that's
about 3.5 metres tall. A bit crude but better than the usual fixed trucks
under longer modules.

The consortium system pretty-much stuffs the prospects for getting a good
tram. A group of companies, including a tram manufacturer, gets together to
put in a bid to build and operate a new system. The bids from several such
consortiums are considered on a range of heads, among which the tram design
is of little significance, hence the tram manufacturer will put forward
their tram model that is cheapest to manufacture (fixed truck). Unless we
separate the process of choosing the tram (with the actual independent
expertise to do that successfully), this situation will continue.

Not to worry, the process of selecting good citybus designs in Australia is
just as screwed up and they *are* chosen directly by supposed industry
experts. We seem to suffer from a general dumbing down, something missing
in professional training and breadth of experience.

Tony P

On Monday, 2 August 2021 at 16:53:54 UTC+10gregsut...@... wrote:

> It is not as though the problem of getting fixed truck trams around tight

> curves hasn't been dealt with in the past nor have solutions adopted by

> highly experienced and capable engineers not been recorded by Technical

> Journals.

>

> NSW Tramways had a long history of operating 4 wheel trams (C, D, E,J, and

> K classes) between the 1890s and the 1950s with a number of 4 wheel service

> trams enduring until the final system shutdown. For many years these trams

> operated, often as coupled sets, on the tightly curved and steep Bondi via

> Belluevue, Watsons Bay (for 30+ years an exclusively 4 wheel tram service)

> and North Sydney lines.

>

> Other Australian systems also had many examples of 4 wheel trams.

>

> The attached page 424 "Bradfield on Electric Tramways"extract from

>

> *Electric tramway : The Spit to Manly, N.S.W. / by John Job Crew Bradfield*

>

>

> http://trove.nla.gov.au/work/7778217?q=creator%3A%22Bradfield%2C+J.+J.+C.+%28John+Job+Crew%29%2C+1867-1943%22&c=book

>

> shows the 'easing of gauge' adopted for decreasing radii of curves and

> also for different rail cross sections adopted as system standards. Most

> outdated of course as it had nothing to do with real (heavy) railways!

>

> Regarding the "institutionalised extablishment" I recall attending a

> presentation by a leading practitioner of this group as he expounded on

> CSELR light rail track. When questions from the floor were invited I asked

> if any consideration had been given to easing the gauge. He first appeared

> non plused, then followed the "Pesant, I am the expert consultant, put down.

>

> Unfortunately one of attendees in the audience piped up "I work for XYZ

> concrete sleeper manufacturers and we have made easing sleepers to special

> order for Melbourne", the Chair of the meeting immediately called for the

> next presenter to present a paper on a different subject!

>

> One could also note that after their sterling work on the CSELR

> WSP/Parsons Brinckerhoff were commissioned by TfNSW to undertake similar

> work on the Parramatta Light Rail.

>

> Greg

>

>

> On 2/08/2021 2:42 pm, TP wrote:

>

> (snip)

>

> As far as I know, there is no curve on CSELR less than 25 metre radius

> which is the generally accepted minimum for a tram with fixed trucks,

> though it by no means immunises the system and its trams from damage,

> especially when there are quite a few curves and many trams, as on CSELR.

> Many of these modern light rail systems are basically long runs of straight

> lines (typical grid city layout, which Sydney isn't), with the occasional

> turn to navigate. A fixed truck tram is simply unsuitable for a line

> profile that has frequent curves. New systems like Adelaide, Gold Coast and

> Canberra are examples of systems with long straight runs and only a rare

> corner or curve, so they get by with the fixed truck trams. None of

> Sydney's three systems has significant straight runs.

>

> (snip)

>

>

> So many mistakes and with little prospect of being rectified, as I see

> that the new light rail mob with their heavy rail background have become

> the institutionalised establishment , complete with their own

> prefessionally internalised annual conferences where they can share their

> lack of knowledge with each other, unchallenged by those "outdated" folk

> from legacy systems. Though, it is true that Melbourne professionals do get

> along to these talkfests but, if they proffer any educational role, it

> doesn't seem to have any effect. I wrote a letter to TAUT about all this

> recently. Time to lift the game and not rest on laurels.

>

> Attachment

>