The system Sydney Trains uses to monitor the strength of the state's rail bridges was missing information for more than 200 structures, according to a confidential analysis prepared late last year for transport authorities.
Fairfax Media first revealed gaps in the monitoring of the state's rail bridges in June.
A rail bridge over Duck River at Granville, one of the bridges for which the state does not have a load rating.Credit:Peter Rae
Following those investigations, which also demonstrated that rail authorities had incorrectly denied that there were any oversights in its bridge monitoring, transport minister Andrew Constance said he had asked Transport for NSW to commission an independent analysis into its "Bridge Management System" (BMS).
That analysis, by engineering consultancy Parsons Brinkerhoff has, confirmed that Sydney Trains' BMS "has data missing".
The Skytrain elevated section of the Sydney Metro NorthWest project has been plagued by construction issues.Credit:Janie Barrett
In particular, Parsons Brinkerhoff's report found that Sydney Trains' BMS was missing load ratings for 25 per cent of the bridges for which it is responsible, or 207 of 825 bridges.
Load ratings are using to gauge the strength of a bridge and the weight it can carry.
"Missing data in BMS has the potential to impact confidence in the data of bridges without load rating, and the efficiency and effectiveness of bridge management activities," the Parsons Brinkerhoff report, obtained by Fairfax Media, says.
One of the problems with not knowing the load ratings of different bridges is that transport authorities then have little guidance as to where they should put their resources.
The Parsons Brinkerhoff report also questioned Sydney Trains' methods for filling in the gaps in its information system for bridges.
"Having no clear priority could lead to lower priority bridges being closed out first potentially leaving higher risk or more difficult to resolve bridges later, impacting on risk or plan delivery," the report, dated August 2016, says.
"Lack of clear risk and mitigation decision making potentially impacts on the consistency and optimisation of decisions."
The confirmation of gaps in Sydney Trains' BMS in the Parsons Brinkerhoff report follows the agency's initial denial of any problems with its information.
"I have been informed that all Sydney Trains' bridges have load ratings and are inspected," the manager of Transport for NSW's Information and Privacy Unit wrote to Fairfax Media following a freedom of information request last year. Transport for NSW subsequently conceded it did not have load ratings for all bridges.
In a response for this story, a spokesman for Sydney Trains last week said the agency had load ratings for all bridges in the network.
"Sydney Trains has a rigorous ongoing program of inspections and maintenance that ensure bridges across the rail network are safe," the spokesman said.
"Each year, we invest more than $30 million on bridge maintenance and replacement work. Structural examinations are undertaken every two years and depending on the age and condition of a bridge, may be carried out more frequently."
Separately, the "Skytrain" rail bridge section of the Sydney Metro NorthWest project has had multiple construction issues in the past year.
Jacob Saulwick is City Editor at The Sydney Morning Herald.