A special inquiry is being launched into why the newly-constructed Broadway underpass in west Belfast became submerged in water during heavy rainfall in Northern Ireland over the weekend.

During the worst of the flooding, the underpass stretch of the Westlink motorway was under 20ft of flood water after a nearby river burst its banks.

At least 10M gallons had to be pumped into the Clowney Water river, once water levels had lowered in the river. The Fire and Rescue Service and Roads Service’s contractor HMS were then faced with 2-3 inches of slit, mud and debris which had to be removed using excavators and tankers.

The underpass’s city-bound and country-bound carriageways reopened to traffic on Tuesday morning.

The Roads Service, part of the Department for Regional Development, is to examine why the underpass, only completed in July, flooded.

The Stormont Committee held a special meeting on Tuesday to discuss the causes, impact and response to the flooding with officials from the Roads Service, the Rivers Agency and Northern Ireland Water. Independent consultants are to look at the intensity of the rainfall, the cause of the flooding, and the Broadway underpass’s design and construction standards.

Roads Services is also set to review the design, operation and management aspects of the Clowney Water System with the company responsible for the M1/Westlink scheme’s design, build, finance and operation.

More than 60mm of rain, equivalent to the average rainfall for August, fell within a 12-hour period on Saturday.

Parts of the M1 motorway linking Dublin in the Republic of Ireland and Belfast in the north were closed, as were 37 other roads.
Two bridges collapsed because of the downpours – one at Fairy Glen, in Rostrevor, County Down, and one on the Lurgan to Cahone road at Rathisland.

There was also at least one landslide causing a train to derail in County Laois.