Max Logan with the Transportation Investment Corporation, the company that runs the bridge, said the brine solution used to de-ice the bridge wasn't strong enough.
The solution should have lasted about 48 hours, but it stopped being effective at about 5 a.m. PT.
Logan said the bridge was monitored six times between 10 p.m. Wednesday and 5 a.m. Thursday, and the ice built up some time between 5 and 6 a.m.
However, that was just one factor that led to the accidents which backed up traffic in both directions during the morning commute.
Logan said motorists driving too fast for the conditions and limited visibility due to fog also contributed.
No one seriously injured
Accidents involving 40 vehicles blocked many of the east and westbound lanes of the span for much of the morning, although all the crashes had been cleared by 8:30 a.m.
Police reported several minor injuries and say one person was taken to hospital, but add no one was seriously hurt.
Public transit service was also affected by the traffic jam. The #555 Port Mann Express was rerouted to Surrey Central SkyTrain Station.
Fog and icy conditions are being blamed for the crashes and motorists are advised to exercise caution in the area.
The new bridge has only been open for about a month but this already the bridge's second major incident.
Snow the week before Christmas caused ice build-ups on the bridge's support cables, forcing closure of the bridge after chunks of ice plunged down on passing cars, injuring several people and damaging dozens of vehicles.