Concern has been raised about rumble strips along the edge of State Highway 6 between Makarora and Lake Hawea, which is popular with cycle tourists. Photo: Mark Price

Motorists used to squeezing past cyclists in the face of oncoming traffic may have to take a different approach this summer.

The addition of rumble strips along the edges of many highways earlier this year is changing the way cyclists behave.

Cycle tourists spoken to by the Otago Daily Times say on narrow roads where the rumble strips are near the edge of the seal, they are forced further out into the traffic.

As a result, motorists approaching them from behind must either slow down to their speed or cross the centre line.

A German cyclist who had just completed the trip along the narrow part of State Highway 6 between Makarora and Lake Hawea said where there was no shoulder to cycle on outside the rumble strip, he made sure to take up ‘‘his space’’ in the traffic lane.

He did this to discourage motorists overtaking when it was not safe.

Most motorists slowed down, but not all did, he said.

Wanaka businessman Richard Hutchison told the ODT while driving from Makarora to Wanaka he saw a cyclist almost run over.

‘‘A cyclist in front of a van ahead of us endeavoured to move further left because he heard a vehicle coming.

‘‘His front wheel got caught in the [rumble] strips and he nearly fell in front of the van.

‘‘Only by an extremely small margin was the driver able to avoid running over the falling cyclist.’’

Mr Hutchison said the decision to put rumble strips on the edge of narrow roads was beyond his comprehension.

‘‘On such a narrow road it forces cyclists towards the centre of the road.

‘‘They have no chance to stay as far left as possible.’’

He believed those making decisions about where to place rumble strips should ‘‘get on bikes, ride on some of the roads and see how vulnerable they would feel’’.

‘‘Our roads in many cases are far too narrow for the amount of traffic they now have to cope with.

‘‘I would urge that, before the onset of holiday traffic, the [rumble] strips on the left-hand side of [SH6] are removed urgently.’’

The NZ Transport Agency introduced the rumble strips as a ‘‘simple but effective safety improvement that can help prevent deaths and serious injuries’’.

‘‘They can reduce fatal run-off-road crashes by up to 42% by giving drivers a wake-up call if they stray across the line,’’ a spokeswoman said.

‘‘They also make the edge line more visible to drivers, especially when it’s dark or in wet conditions.’’

However, the NZTA has been unable to provide the ODT with any evidence to show rumble strips improve the safety of cyclists.

Some strips in the Upper Clutha and near Oamaru and Kingston were removed when local cycling groups complained they made cycling more dangerous.

New NZTA guidelines:

WHEN rumble strips are being considered the following principles apply:

The desirable shoulder width for cyclist use is one metre or more. Although having a one-metre width between the rumble strip on the highway and the start of the grass road-side verge is desirable, rumble strips can also be installed on narrower shoulder widths, given the safety benefits they provide.

The minimum shoulder width for cycle use is 500mm.

Between 500mm and one-metre rumble strip may still be used depending on the location on the highway and possible effects upon cyclists using the highway in that location. For example, a downhill section of highway may be an area where the narrower width is ruled out, given the safety issues for cyclists on that part of the highway.

Where these dimensions cannot be achieved (by shoulder widening or revising the lane widths) and the shoulder width is 300mm or less, then the rumble strips should be placed in the shoulder to the left of the edge line. This will mean that cyclists would ride in the traffic lane - something they already do when the shoulders are very narrow.

For shoulder widths between 300-500 mm, where the provision of a wider shoulder has not been possible, then other treatments, such as high-performance line markings, may be considered as an alternative to rumble strips.

Discussions with cyclists have revealed that often what is important is a consistent shoulder width that enables cyclists to stay on one side of the rumble strips or the other. This needs to be combined with the appropriate provision of gaps in the rumble strips to allow cyclists to cross the edge line.

mark.price@odt.co.nz