Emas concept is an arresting idea

A LOT of noise is coming from the west at the moment about the airport.

The debate, essentially, is about how to cope safely with overrunning or undershooting planes – when work on resurfacing the runway takes place, the Civil Aviation Authority will expect improvements to the current set-up.

Should Guernsey just use a grass runway end safety area or, for some extra money, add in the relatively new collapsible concrete concept known as Emas?

Everyone has been waiting for the independent report on Emas, the Holy Grail in some eyes and a technology that could keep La Mare Road open and avoid the need for the compulsory purchase of a family's field.

Compiled by Mott McDonald, the report was released last week and instantly gave all sides hope.

It concluded that Emas was an acceptable option that would be safer and need less land, but it came at an additional cost of some £6m. – or more if you had a store of concrete blocks for a quick repair.

Public Services, Bernard Flouquet's department behind the airport development project, is sticking by its guns with the original scheme.

The consultants came up with yet more options using grass runway safety ends that it said were preferable to the current plan too, but these have so far been largely ignored.

At the end of the month, PSD will come back to the States with its recommendation to close the road and compulsorily purchase the Le Messurier family's field.

It pulled the report in January because Mott Mcdonald's report was not available for all deputies in its final form, although a draft had been seen by some.

There was a feeling it was in danger of stumbling at this small but important hurdle as it looks to get the project under way because deputies did not have enough information to make a decision.

They have already rejected Emas once, when deciding in October 2009 to press ahead with the £80m. redevelopment work, but the CAA has since issued policy guidance that put the technology back in the frame.

Just where would we be now if the States had signed off on PSD's proposal at that time and the department had not been told to come back to the Assembly again with the project?

Mott McDonald concluded that the Emas option put to States members then would not have been compliant with various safety regulations, which does little to create confidence in the original report, but it has devised an Emas scheme that would.

What we know of this States is that when there is any whiff of uncertainty, any doubt that something else could be better, they tend to shy away from a decision – just remember how PSD's waste plans got shot down.

The consultant's report is entirely technically focused and makes little allowance for any of the cultural, environmental or historical arguments which can have an impact in the political decision-making process.

One thing it does is highlight that PSD's option is not the optimum solution that can be reached even within the confined circumstances the airport is in, although it is the cheapest.

The CAA recommends runway safety areas for Guernsey airport's category as being 240m long by 150m wide – the minimum is 90m by 90m.

At the east end of the runway at Guernsey, the existing Resa length is about 80m. At the west end, the existing Resa length is about 120m.

There is insufficient land within the existing airport boundary to provide 240m long by 150m wide Resas and maintain existing declared runway distances.

Mott McDonald, in consultation with the director of civil aviation, concluded that because of the site's constraints, a shorter Emas-enhanced Resa would be consistent with CAA policy.

If keeping a road open is not worth an extra £6m., safety considerations and the extent of damage to an overrunning aircraft might be because Emas has further benefits.

'The performance of the latest design of Emas does not materially change between dry and wet conditions or if overlain by snow,' the Mott Mcdonald report stated.

'The manufacturers state that their latest design is also now less susceptible to jet blast erosion and they claim it requires less routine maintenance.

'An overrun into an Emas bed is a more predictable event than an aircraft overrunning onto a grassed Resa, even if that is built to the recommended dimensions.

'The extent of aircraft damage and injury to its occupants is also much lower than on a graded overrun area in all the actual incidents to date (although the number so far, seven, is small). Because it is designed to limit the stress applied to the undercarriage, a low level of damage is to be expected and is a benefit of the concept.

'Based on the evidence presented and the experience of actual events to date, Mott MacDonald is satisfied that an overrunning aircraft entering into an Emas bed (within its design parameters) will be brought to a controlled stop with minimum injury to its occupants and minimum damage to the aircraft itself.'

Mott McDonald devised two other scenarios which it showed had advantages over the current scheme, particularly in making the widest possible grass Resa, but both come at a small cost.

But Emas is where the eyes are focused.

The Emas scheme would produce wider safety areas with an overrun performance approximately equivalent to 240m-long Resas at both ends – meeting the CAA's recommended length.

The extension of the airport site to the west is also reduced.

'Its selection depends on the perceived benefits of the reduced site area and its performance compared with the additional costs,' the reported said.

In the end, the argument could come down to: What price is safety?