Mr Dick said trucks had difficulty carrying fully-loaded high cube containers. Two return trips per day between Gisborne and Napier are usually not possible.
"Road safety is already an issue and risks will increase as heavy traffic volumes inevitably increase. Reliable sources indicate that the additional truck movements quoted by Kiwi Rail are significantly understated."
The decision ensured Gisborne and the East Coast would be confirmed as one of the most isolated regions in New Zealand, Mr Dick said.
"It is most unfortunate the Government has chosen to ignore the fact that the Gisborne and Hawke's Bay economies are highly export focused and need reliable and economical transport links to get their goods to market.
"Gisborne and Hawke's Bay are where New Zealand earns its living in the world and deserve better recognition."
The Government's announcement it would spend an additional $4 million on passing lane opportunities between Napier and Gisborne was little consolation.
National's Tukituki MP Craig Foss said the rail line was "mothballed but not closed" and if there was a case to reopen it, it would be considered by KiwiRail. "But the economics have to stack up and at the moment they don't."
He said since the rail line had been out of use there had not been a significant increase in traffic or problems on State Highway 2 between Napier and Gisborne.
"During the past nine months we have seen an extra five trucks a day while the line has been out of action."
Napier MP Chris Tremain said there was no evidence road transport freight costs would increase.
"The fact is that rail transport on this corridor has been uneconomic. If it had been competitive the line would not be being mothballed and we would have seen significant volumes of freight shifted to rail.
"Over the last 10 years road closures for longer than 10 hours have occurred on average once per year.
"This is hardly inadequate given that the rail line has been closed on various occasions for months at a time and not once over that period has the railway been substituted for a closed road."