One of Brisbane busiest train stations - Fortitude Valley - needs millions of dollars of work to prevent a repeat of flooding that stopped all trains in both 2014 and 2015.
A six month Queensland Rail investigation has blamed drainage pipes under the station that are too small, rail tracks that are six metres lower than the rest of Fortitude Valley and one drainage pipe that was 80 per cent blocked.
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New buildings or "extremely old" drainage may have caused Fortitude Valley train station to flood "three times in one season".
These three facts – plus torrential rain in November 2014 and May 2015 – combined to put 30 centimetres of water over the train tracks in November 2014, cancelling hundreds of trains for hours.
The blunt report, by consultants Jacobs, has put forward four options to fix the problem and puts the cost of repairs by widening drainage pipes at between $17.1 million and $19.2 million.
It makes clear that if repairs do not go ahead – and it rains heavily in summer 2016 – the very same flooding will occur if it rains torrentially for 40 minutes.
"The primary cause is the rail corridor is situated in a cutting six metres below the natural topography and the secondary cause is the lack of capacity in the combined QR and BCC drainage infrastructure," the report's executive summary says.
One repair option involves cancelling all trains through Fortitude Valley for several weeks, the report says.
The damning report shows neither Queensland Rail nor Brisbane City Council were aware one drainage pipe was up to 80 per cent blocked, despite CCTV cameras.
Work to replace drainage pipes under a metre in diameter with larger pipes (two metres wide) is set for the second half of 2016, most likely for between 16 weeks and 45 weeks at night.
What the repairs mean for the Valley
One option to put bigger drainage pipes under 680 metres of Wickham, East and James Street would be a "significant challenge" to a heavily-trafficked part of Fortitude Valley.
"In addition to commuter traffic, the construction phase would also require consideration of the impacts on local businesses and also the safety of patrons of the numerous bars and nightclubs in Fortitude Valley," the report says.
That repair option could take 30 weeks, the report says.
However if trains are cancelled on all four tracks, the repairs could be finished "within weeks", however the disruptions would "present a challenge to Queensland Rail", the report says.
Fortitude Valley caters for 2.5 million train passengers a year.
Repairs will be a logistical nightmare for Queensland Rail, which will try to complete most of the work at night.
"The installation of the twin circular culverts and numerous gullies would still require the removal of all four tracks (including rail, sleepers and ballast) for approximately 40 metres and result in considerable disruption to the rail traffic," the report says.
When will the work be done?
The Jacobs study assumes the repair work will be done in four-hour chunks between 12 am and 4am over 45 weeks from September 2016. However neither Queensland Rail nor Brisbane City Council have agreed to that.
Alternatively if trains could be completely cancelled on all four tracks, the repairs could be completed "within several weeks," the report says.
What are Queensland Rail and Brisbane City Council saying?
Queensland Rail and Brisbane City Council last night downplayed the extent of the repairs.
"Whilst discussions with Brisbane City Council are ongoing and any plans to improve drainage are still being considered, it is expected construction works would be completed with minimal impact to rail customers," a Queensland Rail spokeswoman said.
"As always, we would work closely with TransLink if required to ensure alternate transport is provided and ensure our customers are notified well in advance."
Brisbane City Council said the Jacobs report showed it simply rained too heavily for the drainage to cope.
"The report indicated that the unusually high-intensity rain contributed to the flooding and current drainage capacity was unable to move the water quick enough on this occasion to prevent temporary localised flooding," a spokeswoman said.
No decision has been taken on whether trains will be cancelled through Fortitude Valley in order to get the repairs done faster.
"Ongoing discussions are underway with Queensland Rail about the recommendations and investigations have commenced to assess the cost of implementation of any works," a statement from Brisbane City Council reveals.
What the report recommends.
Option 3 involves building a new 680m long, two metre wide by one-metre high box culvert along the rail corridor that would replace the existing 900mm pipe. The cost would be $19.2 million
This 'relief culvert' would travel under Wickham Street, East Street, James Street, Fortitude Street and join the exiting BCC network with Fortitude Street and Wandoo Street.
Option 4 involves less work under the station, but more work outside the rail station.
In Option 4, the 600mm diameter circular culvert under Brunswick Street would be replaced with a two-metre by one-metre rectangular box culvert.
It would pass under Wickham Street, East Street, James Street, Fortitude Street, until joining the exiting BCC network under the intersection with Fortitude Street and Wandoo Street. The cost of this option would be $17.1 million.