The New Zealand Transport Agency says the main roads out of Christchurch were open on Tuesday afternoon after the quake.
The quake occurred at 12.51pm, causing multiple deaths and injuries.
There were also reports of major damage to local roads, as well as liquefaction and surface flooding.
The agency said the Rakaia Bridge on State Highway 1 south of Christchurch and the Waimakariri Bridge on State Highway 1 north of the city were open.
The Lyttleton Tunnel had been re-opened for emergency vehicles to use on Tuesday evening, the agency said.
A control building at the tunnel was seriously damaged in the quake. The agency said an assessment of the damage would be carried out on Wednesday morning to determine whether the tunnel can be reopened for use by light vehicles.
The Ferrymead Bridge was reported to be impassable because of rising water.
KiwiRail said the TranzAlpine service was stopped at Greymouth and the TranzCoastal stopped at Picton. A spokesperson said no injuries have been reported and all passengers were safe.