Risk to people on the ground

Public Safety Zones (PSZs)

Aircraft accidents are, thankfully, a rarity but they do happen and the areas close to the ends of airport runways are particularly vulnerable. In the late 1990s, the Government commissioned studies of the risk to people on the ground near airports with the aim of providing guidance to local councils faced with applications for building within these risk zones. This guidance was published in 2002 as Department for Transport Circular 1/2002.

The guidance to planning authorities defines Public Safety Zones (PSZs) at the runway ends within which Councils are expected to limit the grant of planning permission. The PSZs approximate to tall triangles stretching over the ground under the approaches to the runways with their bases on the runway ends. The main PSZ represents the area within which a person on the ground is exposed to a risk of death or serious injury which exceeds 1 in 100,000 every year. The Government regards this level of risk as unacceptable but assesses the cost of removing the risk (eg by relocating a resident and knocking his or her house down) as too great. Within this PSZ, planning applications for development which would increase the average level of occupancy of the land should be refused.

Luton’s PSZs

At Luton, the western 1 in 100,000 PSZ stretches across Stockwood Park to the M1 and includes a number of homes in Cutenhoe Road and London Road. To the east, the PSZ reaches Breachwood Green. Luton Borough Council has applied the PSZ policy to refuse permission to divide houses into flats. The areas of the PSZ’s falling within their Districts should be shown on the proposals maps accompanying the Local Plans of Luton Borough Council, South Beds District Council and North Herts District Council but, as only Luton has published its PSZs, we show them diagrammatically here.

Of more concern at Luton is the inner PSZ, the smaller triangular area shown in our diagrams, within which the risk of death or serious injury exceeds 1 in 10,000 each year. At the eastern end of the runway this PSZ is only crossed by a minor road but to the west the main route to east Luton, the A505/A1081 Airport Way, passes beneath the flight path within 400 metres of the runway. Within this zone, the Government regards the level of risk to be so great that all land uses involving high levels of occupancy must be removed at the Airport’s expense. Only uses such as long-term parking and unmanned equipment are permitted in this area.

High risk on Airport Way

Using the method for the calculation of risk used by the Department for Transport and based on air and road traffic data for 2005, LADACAN has calculated that the risk of a single fatality of a user of this road is 5 in 1,000 each year. This is a very high level of risk – the Health and Safety Executive places a limit on individual risk in the workplace of 1 in 1,000 – and we believe it to be an under-estimate as we have used conservative assumptions to estimate it. We have, for example, used average figures for daily air and road traffic whereas the daily peaks of both tend to coincide, so increasing the occupancy of the roadway when the risk of accident is greatest.

Despite this high level of risk and the Government’s guidance that transport facilities should be treated as if it was residential development, Luton Borough Council granted itself planning permission to carry out the upgrade of Airport way as part of the East Luton Corridor improvement which is in hand now. This will increase the number of people at risk by increasing capacity, applying speed limits and placing traffic lights in the danger area.

In reaching its decision, the Development Control Committee argued that it was unreasonable to allow an identified individual to live in a high risk location irrespective of his or her wishes but reasonable to expose others to the same risk without informing them because they would each only be at risk for a short period. The result in terms of fatalities would, of course, be the same.

Risk enhancement from increased air traffic

The Government guidance, like the equivalent for aircraft noise, is intended to guide planning decisions for locations outside the airport fence. It is a simplified approach which should not be applied to airport development which would increase air traffic and, hence, the risk to people on the ground. It is expected that any planning application for airport development which could increase air traffic would include a thorough assessment of the increase in risk which would result.

It is also to be hoped that a thorough risk assessment will be carried out if/when an application is made for a stadium complex to be built under the main departure route at junction 10 of the M1. This danger would be removed if NATS’ proposal to re-route westerly departures over south Luton is implemented.

Luton & District Association for the Control of Aircraft Noise - site updated 06 July, 2008