Re: Bridges
  Robert Taaffe

Hello Rod

A couple of clarifications:

1 the Tasman bridge in Hobart - road traffic is stopped just as a ship (with tugs) approaches - about 5 mins all up. Happens in the non peak about once or twice per day.

2 the resupply boat - someone made the vessel wider than the standard and it appear did not check with the port authorities earlier enough re the mods. The concern was like what happened at Baltimore. Anyway it would make more sense to install a fuel pipeline or a fuel barge. It was not the bridges fault

3 re the wipe out of the two tugs. That was in Devonport and last time I went through there did not appear to be anything impeding normal operations.

4 - concrete encasement post Granville. Only bridges at risk were concrete strengthened - steel trestle supports or somewhere like the Goulburn St carpark and North Sydney were a collapse would the catastrophic.

Many people who think up the original designs or a change of use do not fully review the possible consequences.

A bigger worry for the Baltimore collapse was why did the bridge suffer a cascade failure. Sounds like there a safety factor of 1. Not enough.

Bob T

> On 1 Apr 2024, at 10:05 am, 'Roderick Smith' via TramsDownUnder tramsdownunder@...> wrote:


> Roderick.


> With the world in bridgephobia, hasty preventative measures are being put in place to avoid a repetition of the Baltimore disaster. Large ships must now have tug assistance to pass under ,may bridges (eg Sydney Harbour, Brisbane Gateway); emergency traffic signals are being installed.

> Tasmania has already banned the Antarctica supply boat Nuyina from passing under Tasman Bridge: it has to go to Burnie to bunker. That followed the collapse of the first Tasman Bridge, and a more-recent sinking of two tugs by an out-of-control cargo ship.

> Perth and Adelaide are safe: lack of depth prevents large vessels from reaching their railway bridges.

> Victoria had encased bridge supports in concrete after the Granville disaster. It has now reduced speed limits over the Spencer St spans of Flinders St Viaduct (even lower than the existing low limit) and over Napier St, Footscray. Testing has revealed a design defect in all spans of the first elevated project: Caulfield - Dandenong. Pending the design of suitable rectification, a speed limit has been imposed over all spans which cross roads. A spokesperson stated: 'This will have timetable implications, but customer safety is our number one priority. We thank you for your patience and understanding'.


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