No one is reported to have suffered any injuries.
A KiwiRail spokesman said staff were onsite and a crane was being brought in to remove the truck.
"The line will be then be inspected and any necessary repairs carried out before the line is reopened. We expect that to be later today."
The line carries freight, primarily logs and timber products.
Meanwhile, a horse truck has rolled onto its side on Trig Rd, in Whitford today.
At least one horse is trapped inside the vehicle, with rescuers at the scene. St John confirmed no people had been injured.
The crash occurred about 2.30pm. Police are unsure what caused the vehicle to crash.
About the same time, two cars crashed in Pāpāmoa but the incident is believed to have been minor.
About 2.45pm, a car left the road in Pāpāmoa and hit a street light, knocking it over.
The crash happened at the intersection of Parton Rd and Tara Rd.
A police spokeswoman said it was not clear what injuries the driver had sustained.
Earlier today, there was a two-car collision on SH29 in the Kaimai Range and another two-car crash on SH36 between Tauranga and Rotorua. Both crashes resulted in blocked lanes.