The rise was largely due to fatal and serious injury motorcycle crashes, which rose from eight between 2002 and 2006 up to 18 in the following five years.
NZTA figures showed between 2007 and 2011 there were 282 crashes on the Rimutaka Hill Road, of which two were fatal, 30 were serious, 76 were minor and 174 were non-injury crashes.
Nine per cent happened as a result of overtaking, and 8 per cent were rear end/obstruction collisions.
Crash factors showed that road issues were a contributing factor in 38 per cent of crashes on the road, while speed and poor handling were factors in 34 per cent of crashes.
Poor observation and poor judgment were contributing factors in 14 and 13 per cent respectively. Factors which hampered driving such as fatigue and alcohol were directly associated to 5 per cent of crashes.
NZTA said between 2009 and 2011 $16 million was spent smoothing out Muldoon's Corner, the sharpest and tightest corner on the road. Other corners were also eased or straightened.
A new guard rail was added and resurfacing completed on a one kilometre section of road.
Last Saturday, a woman motorcyclist suffered fractures to her lower and upper body after she collided with an oncoming vehicle near Featherston.
