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Despite bikers’ strong objections to them, wire-rope barriers are continuing to save lives on the open road. BY GAVIN RILEY
But not everyone feels that way – and their view has been reinforced by one terrible accident. Last October a 21-year-old motorcyclist was killed when he hit a wire-rope median barrier on State Highway 1 near Papakura on the southern outskirts of Auckland. The impact practically sliced him in half. That he was travelling at an estimated 150 kilometres per hour at the time of the accident did not deter enraged bikers from forming the CheeseCutter Campaign Group, which set up a website, issued a press release and launched a petition calling for an immediate moratorium on the use of wire-rope barriers until a review is undertaken of their effectiveness and safety, with particular reference to motorcyclists. The group maintains that motorcycle lobby groups in Europe and Australia have been successful in having wire-rope barriers removed and their future use banned. “We have collated reports and information from around the world which prove that wire-rope barriers are ineffective and potentially lethal to motorcyclists,” the CheeseCutter Campaign Group says. A group member wrote to Prime Minister Helen Clark about the group’s concerns and received a reply from Transport Safety Minister Harry Duynhoven who, not surprisingly, disagreed with its claims. “The safety benefits that wire-rope barriers provide to the vast majority of road users are undeniable and continue to be demonstrated,” Duynhoven wrote. He said Transit New Zealand recognised that all safety barriers, not just wire-rope barriers, can be a hazard to motorcyclists. “However, at this stage, New Zealand crash statistics and international research and experience do not show that wire-rope barriers present more of a danger to motorcyclists than other types of barrier.” The minister said that from 1997-2007 there were nine reports of a motorcyclist killed on New Zealand roads following impact with a safety barrier. Two of those involved crashes at high speed on the Auckland motorway into a median barrier – one a guardrail and the other a wire rope (last October’s fatality). Tensioned wire-rope barriers (WRBs) were developed in Britain in the 1960s by the Bridon group, whose Brifen barrier made its motorway debut there 40 years ago on the M62 across the Pennines. Then in the late 1980s, when roading authorities globally were looking to reduce WRB deflection, Bridon achieved the desired breakthrough by replacing parallel ropes with two or more interwoven ropes – still a feature unique to the Brifen barrier today. New Zealand installed its first Brifen median WRB in 1988, on a stretch of State Highway 1 at the foot of Wellington’s Ngauranga Gorge. The second installation came the following year on Auckland’s northern motorway, between Tristram Avenue and Constellation Drive. Part of Auckland’s southern motorway and sections of State Highway 1 north of Ngauranga Gorge followed – Johnsonville-Tawa, Tawa-Porirua, Porirua-Whitford Brown. In recent years median WRBs (incuding three kilometres of Brifen in late 2007) have been installed progressively along the notoriously narrow Centennial Highway section of coastal State Highway 1 to reduce its high crash rate – 40 killed and 120 seriously injured in 20 years on the 10 kilometres from Pukerua Bay to McKay’s Crossing. A trial 700-metre stretch of WRBs north of Pukerua Bay, put in place in 2004, won the road-engineering category at the 2006 New Zealand road safety innovation and achievement awards. Before the barriers were placed there were seven fatalities in one year. In their first three years the barriers prevented 15 potential head-on fatalities, as recorded by Transit monitoring cameras. This road-safety trial measure was applauded by the motoring public and local MPs Winnie Laban and Nathan Guy – but not bikers, who peddled their cheese-cutter claim and demanded that ACC investigate the danger to motorcyclists. Undeterred, Transit spent $15.2 million to place WRBs along the remainder of the Pukerua Bay-Paekakariki section of State Highway 1 by late last year. There are now just over 190 kilometres of WRBs on state highways, of which almost 130 kilometres are Brifen barriers, manufactured locally for more than 25 years by Auckland-based Bridon New Zealand. Bridon NZ chairman Philip Pearce, an Englishman who has lived in this country and been responsible for the Brifen barrier for more than 20 years, says WRBs have a better safety record than other types of barrier because they absorb much of the impact energy. “One big difference is that with the wire-rope barrier you get a truly continuous ribbon, so when you get an impact, from a truck or whatever, the impact energy is passed all the way back along the ropes in either direction, so that the posts and even the anchors are helping to absorb the impact,” he says. “When you hit a section of guardrail or concrete, all the impact is basically taken on that one section. It can’t absorb the impact over 100 metres on either side. So when a big vehicle hits a guardrail it is more likely to plough straight through. Equally, when a big truck with a high centre of gravity hits a concrete barrier it can be overturned, because you don’t have that deflection to bring the vehicle back into line reasonably gently.” Despite the safety advantages of WRBs for all other road users, Pearce says he sympathises with motorcyclists and can understand why they don’t like any barrier types that have exposed support posts. But he adds: “I don’t feel wire-rope barriers are any more dangerous to a motorcyclist than, for instance, a guardrail. If you fall off a motorbike and are sliding along the ground, it is hitting an upright post which does the damage, whether it is a lighting column, a signpost, a guardrail post or a WRB post.” CSP Pacific supplies (but does not install) several types of barrier, including two WRBs – the tensioned three-wire Armorwire, which is manufactured locally; and Safence, originally three-wire but now four, which is sourced from Sweden but manufactured in New Zealand. Armorwire, acquired by CSP Pacific only last year, has been installed as part of a safety retrofit on a high-crash-rate section of State Highwat 1 at Dome Valley, north of Auckland, as well as at sites in Nelson and the Wairarapa. Safence has been used on many Transit roads, including Centennial Highway, and on a number of local roads, such as the Eastern Hutt Road for Hutt City Council. Safence has a 650mm-deep footing as opposed to the standard 900mm, which was why it was selected for placing along 870 metres of the Eastern Hutt Road, where a medium-pressure gas main runs below ground. Any other type of WRB could have posed a risk to the main and meant slower installation. With WRBs a firmly entrenched safety feature of New Zealand roads, the outlook might seem bleak for motorcyclists genuinely fearful of hitting them. But that’s not the case. Philip Pearce says Bridon NZ will introduce later this year a new version of Brifen specifically designed to address motorcyclists’ concerns. He says what actually kills a motorcyclist who falls off at speed is not the barrier but the posts, and the new Brifen WRB will go some way to overcoming that. “It’s going to incorporate tough but flexible plastic panels which attach to the posts below the ropes, so that if you fall off a motorbike and slide along the road, you’re not actually going to hit a post and come to a suddden stop. You’ll hit a line of plastic panels that are there to protect a body from the posts and allow it to slide along the barrier, just as it would with a concrete barrier.” CSP Pacific also has good news for motorcyclists. It is about to introduce Nu-Guard 31, a low-deflection steel guardrail from the United States that is likely to be used along 900 metres of the Alpurt B2 project north of Auckland. CSP Pacific’s Zalman Paris says the lightweight Nu-Guard 31 is very cost-competitive with wire rope and and can be installed quickly and simply because there is no need for a concrete foundation. “We’re very excited about Nu-Guard 31. It’s an amazing product,” he says. Meanwhile, Transit traffic and safety manager Dennis Davis says wire-rope barriers are extremely effective at reducing the severity of crashes and Transit intends to continue installing around 25 kilometres of them each year. Contractor Vol.32 No.3 April 2008 |
You would think road users throughout the country would be pleased and relieved that more and more dangerous stretches of highway are being made safer by the introduction of crash barriers, irrespective of whether they are of the concrete, guardrail or wire-rope type.