Noah Donohoe who was found dead in a storm drain in north Belfast in June 2020(Image: PA Media)
Mr Benn had previously given evidence along with three other expert witnesses last month.
The inquest heard all four thought it was âextremely unlikelyâ Noah entered the culvert system at any other point.
Mr Benn said the alternatives were manholes, which he described as having heavy covers, designed not to be easy to lift, and if Noah had entered via a manhole the cover would have remained off.
He said other parts of the watercourse were fenced off, while another section would have involved wading through deep mud, and the train depot where the section of storm drain where his body was found, is gated with 24-hour security.
Meanwhile, the experts were at odds over whether Noahâs body would have moved in the tunnel.
Mr Benn said Noahâs body could have moved a short distance downstream with the outgoing tidal flow, while the other experts felt any movement would have been short, less than a few metres.
The inquest heard Mr Benn was involved with drafting guidance on culverts in 2010 and 2019, and trained staff at Northern Irelandâs Department for Infrastructure on that guidance. He was instructed by the department as an expert witness for the inquest.
Mr Benn was also described as having disagreed with the other expert witnesses over whether there should have been a security screen and fencing at the culvert which was refurbished in 2017.
On Thursday he warned that fencing in the area would have been very costly and difficult to put in.
In terms of security screens at culverts, he said they can lead to other dangers, adding that the flooding of the Westlink bypass in Belfast in 2008 was caused by a security screen at a culvert.
Counsel to the coroner Peter Coll KC, questioned Mr Benn on his assessment of the risk or hazards of the culvert.
Mr Coll suggested that due to it being dark, cold and the storm drain tunnel being so long and filling twice a day with the tide, that it was a âseriously dangerous place for a 14-year-old child, unauthorised, to be inâ.
Mr Benn responded saying: âI wouldnât go as far as to say itâs seriously dangerous.â
Returning to resume his evidence after lunch, Mr Benn said the culvert âwasnât high riskâ because of hazards being unlikely, terming it instead as âmedium riskâ.
Source: https://www.belfastlive.co.uk/news/belfast-news/extremely-unlikely-noah-donohoe-entered-34028488