THE collapse forced police to close off part of Nathan Road throughout the day, forcing thousands of evening commuters to make lengthy detours. But fears the accident would cause a gridlock were not realised, with police reporting heavy traffic but no major congestion during the evening rush hour. Immediately after the collapse, Yau Ma Tei District Commander Dave O'Brien, expressing concern over possible congestion, said the road could not be reopened until safety could be assured. But police traffic control reported no major blockages last night. While southbound vehicles were allowed through, northbound traffic was forced off Nathan Road on the stretch between Kamsu Street and Jordan Road. Buses running north along Nathan Road were diverted through Austin Road, Canton Road, Jordan Road and Gascoigne Road back onto Nathan Road.