Emergency services were called to the crash at the Ellerton Railway Overbridge, near Kekerengu and the intersection with Ellerton Valhalla Rd, about 11.10am on Monday.
A police spokesperson said nobody has been injured in the crash.
"However, the road is blocked and is likely to remain so for several hours until the heavy vehicles can be removed."
A Waka Kotahi NZ Transport Agency spokesperson said the road is expected to reopen by 4pm.
Motorists are asked to avoid travel as there are no suitable diversions.