An 18-wheeler slammed through a guardrail on the Massachusetts Turnpike westbound in Auburndale around 6 a.m., sliding down the embankment and towards the commuter-rail tracks below.

Newton firefighters arrived to find the driver still in the cab, but were able to help him out.

As a precaution, the MBTA reduced speed on inbound Worcester Line trains until the truck was hauled out.