Hawkesbury River Bridge

 
  Groover Train Controller

Location: A long way from home
I've just finished reading the book on the bridges by Bill Phippen.  Compelling reading by anyone interested in the bridges.  I have a couple of questions for any engineers out there:
1.  Was the second bridge the last great multi span truss bridge built in the world?
2.  If a similar bridge had to built today at that location, what form could it take other than truss?

Cheers

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  apw5910 Deputy Commissioner

Location: Location: Location.
2.  If a similar bridge had to built today at that location, what form could it take other than truss?
Groover
Long grey boring pre-stressed concrete. Covered in graffiti.
  michaelgm Chief Commissioner

2.  If a similar bridge had to built today at that location, what form could it take other than truss?
Long grey boring pre-stressed concrete. Covered in graffiti.
apw5910
Wouldn't that require a huge amount of piers?
Suggest a cable stayed design more suitable two or three piers only.
  br30453 Chief Train Controller

I've just finished reading the book on the bridges by Bill Phippen.  Compelling reading by anyone interested in the bridges.  I have a couple of questions for any engineers out there:
1.  Was the second bridge the last great multi span truss bridge built in the world?
2.  If a similar bridge had to built today at that location, what form could it take other than truss?

Cheers
Groover
To answer your first question, The road-rail bridge over the Burdekin River at Home Hill in Queensland, opened in 1957 and having 10 x 250ft main truss spans has a greater length of trusses.

There have since the been a number of large truss bridges built in the world, even in this century

Examples:

The Ikitsuki Bridge is a continuous truss bridge that connects Ikitsuki to Hirado in Nagasaki, Japan was completed in 1991. It has a main span of 400 meters (1,300 feet), thus making it the longest continuous truss bridge in the world.

https://steelfabservices.com.au/5-spectacular-steel-bridges-from-around-the-world/

Tsukuba Express Tonegawa Railway Bridge completed in 2003, Through type 3-span continuous double-track truss bridge with a total length of 897m

http://www.jfe-eng.co.jp/en/products/infrastructure/bridge/br04.html
  Valvegear Dr Beeching

Location: Norda Fittazroy
If another Hawkesbury ( or similar) rail bridge had to be built, would a box girder design be considered?

(My field of engineering doesn't do bridges!)
  RTT_Rules Dr Beeching

Location: Dubai UAE
2.  If a similar bridge had to built today at that location, what form could it take other than truss?
Long grey boring pre-stressed concrete. Covered in graffiti.
Wouldn't that require a huge amount of piers?
Suggest a cable stayed design more suitable two or three piers only.
michaelgm
Look at the road bridge upstream, this will give you an idea of what 1970's technology could do. I suspect today the spans would be longer, cable pensioned prefabbed box sections maybe.
  LancedDendrite Chief Commissioner

Location: North Haverbrook; where the monorail is king!
If another Hawkesbury ( or similar) rail bridge had to be built, would a box girder design be considered?

(My field of engineering doesn't do bridges!)
Valvegear
Probably not. Suspension bridges and precast concrete viaducts are the usual methods these days. Additionally, if one were to replace the Hawkesbury River bridge then you'd be looking at upgrading to a straighter route at the same time so a different crossing point would be used (c.f just about every East Coast High Speed Rail study done since the mid 1990s)
  grw Station Staff

As a former bridge design engineer many years ago (I was junior engineer in the group that designed the Mooney Mooney Creek Bridge on the Sydney-Newcastle freeway) it most likely that any replacement bridge would be cable stayed. The total length of the Hawkesbury crossing is ~800m which is in the sweet spot for cable stayed bridges. The main issue for the adopted design would be the depth of the foundations and a likely objective of reducing the number of piers given the high depth of the river bottom. A prestressed concrete bridge would likely require 3 or 4 piers (e.g. Mooney has one of the longest balanced cantilever spans in the world at ~220m) whereas a cable stayed could cross it with just two piers. Even today foundations that involve 60m underwater construction are still an issue (the piles on the road bridge on the freeway were at the time the longest piles in the world).

When the design for Mooney was selected it was close call of making it cable stayed but a decision was made that we had experience building balanced cantilever concrete bridges (Pheasants Nest bridge on the F5 freeway 150m centre span; Nepean bridge on Picton Road  slightly shorter than Pheasants Nest) while the first cable stayed bridge in Australia was still in the future (the Anzac Bridge 345m centre span, total length 805m). A bit of context is that the Gateway Bridge in Brisbane (the most recent big bridge in Australia) has a centre span of 260m and was at opening the longest span in the world for a balanced cantilever concrete bridge (not sure if that is still true)

Re the comment of a box girder design. This is more to do with how the bridge deck is arranged and how stiff the deck needs to be in torsion (twisting). Most long bridges use a box culvert because otherwise they are quite flexible in torsion which can be a problem if there is loading on the bridge that is off centre (e.g. a train on one side of the bridge).

A suspension bridge would never be used for a railway bridge at Hawkesbury because they are too flexible and the span for the Hawkesbury is too short for a suspension bridge to be superior to a cable stayed bridge.
  YM-Mundrabilla Minister for Railways

Location: Mundrabilla but I'd rather be in Narvik
Most informative grw. Thanks.
  Groover Train Controller

Location: A long way from home
Thanks GRW
  Valvegear Dr Beeching

Location: Norda Fittazroy
Thanks for the info, grw, and the answer to my question about box girder design.

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