Infrastructure quality more important than speed

Published in Insights, The New Zealand Initiative’s newsletter, 5 April 2013

Last week, considerations to raise the speed limit on some of New Zealand’s open roads made headlines. The current speed limit of 100 km/h has not changed for about half a century – a period that has seen improvements to both cars and roads.

No doubt, a higher speed limit has its benefits, including more efficient freight transport and reduced congestion. It would also bring New Zealand in line with other countries where speed limits are often considerably higher: 110 km/h in most Australian states; 112 km/h in the United Kingdom; and 120 km/h in Portugal. Germany on the other hand does not have a speed limit at all.

So does lifting our own limit bring New Zealand in line with international best practice? Not quite. A suitably built car is not enough to drive this fast. Driving on the right kind of road is far more important.

Although there are a few stretches of road in New Zealand that allow safe travelling at speeds of 110 km/h or even more, these are the exceptions, not the rule. Unfortunately, these motorways are also among the most congested. Increasing the limit may benefit drivers only in the middle of the night but not when most people travel.

Most other New Zealand highways, however, are simply not comparable to motorways abroad on which higher speeds are permitted.

When I still lived in Germany, I often legally travelled at speeds north of 150 km/h – as did everyone else. Germany’s famous Autobahn system is designed for high speeds. The lanes are wide, and there are emergency lanes. There are also guard rails, landscaped medians, and strict rules on overtaking and permitted vehicles. The grade is limited to 4%, road surfaces are between 55 cm and 85 cm deep, and a sophisticated drainage system reduces the dangers from aquaplaning.

It is these engineering features that make it possible to have a super-fast motorway system that is also super-safe. There are fewer than 20,000 accidents per year with less than 500 fatalities. Considering a network length of almost 13,000 km and millions of cars using the Autobahn every day, these figures are low by international standards.

New Zealand should have a debate about its motorways. But by only talking about speed limits, we are having it back to front. Before discussing speed, we need to talk about the quality of our transport infrastructure.

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