Barrier Cream

EU legislation covering the installation of rock fall barriers will replace existing Swiss-approved guidelines. Andrea Roth and David Gibson look at the differences between the two sets and what this means for member states.

Rock falls can threaten people, infrastructure and properties. In north Wales earlier this year a rock fall led to a major trunk road being closed for several hours. In 2006 a rock fall near the Gotthard tunnel in Switzerland killed two people.

The development of flexible barriers have helped mitigate the risks. UK installations have included Golspie in the Scottish Highlands for Network Rail, a large quarry near Skipton, at Dover harbour, as well as sites as diverse as Whitehaven in Cumbria and below the cliffs at Hastings.

Advances in the design of flexible rock fall barriers have enabled engineers to provide cost-effective protection. And advances in technology mean that barriers are now capable of absorbing up to 5000kj - equivalent to a 16t boulder free falling 32m.

The Swiss are acknowledged leaders in this field and have had government guidelines for the design, testing and installation of rock fall barriers for many years. Swiss government organisation Bundesamt fur Umwelt (BAFU) is the country's regulating body for barrier design, manufacture, testing and installation.

BAFU's guidelines - recently revised - have been the benchmark for rock fall barrier kits around the world, including the UK and Republic of Ireland. However, on I February 2008 the EU endorsed new European Organisation for Technical Approvals (EOTA) guidelines (ETAG 27) for rock fall protection kits.

Owing to the testing requirements set out in ETAG 27, the days of consultant/contractor design barriers are numbered. Specialist suppliers will have access to off-the-shelf kits that, when properly certificated by recognised test bodies, will carry the all important CE (European Conformity) marking for EU use.

Barriers and differences
Several points are worth noting here. The BAFU guidelines have been in operation since 2001 and are still the only standard for properly certified barriers.

However, the passing of ETAG 27 means the new guidelines are mandatory in all EU countries. There is no transition period, meaning it is up to member states to decide on implementation.

So far, France has given its implementation date as October 2010 with Austria putting it into practice in 2011.

To obtain European Technical Approval (ETA) a manufacturer needs:

• A testing body, with a test site, which is notified for ETAG 27 (see the Nando website from the European Commission)
• An approval body (www.eota.eu)
• An inspection body for continuous factory production contrdl (FPC)
• A certification body for obtaining the CE marking.

Care needs to be exercised when considering ETAG 27. There are three categorIes of barrier allowed - with differing residual heights offered after the first impact.

Clients and consultants need to be aware that a barrier in class C may have no residual height after the initial impact. These will not provide any protection in the case of a secondary rock fall. Category B is also a lesser category with only limited residual height.

Also, the BAFU guidelines limit maximum deflection, while ETAG 27 does not. This could be very important if the barrier is placed close to the people or structure being protected.

In addition, while some manufacturers may claim that their barriers meet ETAG 27 requirements - and produce some form of certificate, - this is not the same as having an ETA issued by an approved body. Only in this way may a CE certificate be issued. The main differences between Swiss and EU guidelines may be seen in the table opposite.

Andrea Roth is head of the technical department of Swiss rock fall barrier kit manufacturer Geobrugg; David Gibson is business development manager with contractor Ritchies - Geobrugg's certified product installer in the UK and the Republic of Ireland.

Article courtesy of Ground Engineering - October 2008