Cabinet Office UK Resilience

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Interim Report - November 2001

Sirens and Public Address Systems

The work of the Sirens & Public Address Group
The Group undertook the task of attempting to identify the locations at which sirens were used throughout the United Kingdom in order to establish whether it would be feasible to suggest a national standard for the use of sirens.

Responses to the NSC's questionnaires provided insufficient data on which to base any conclusion and therefore it is not possible at this stage to identify whether there is sufficient commonality of systems around the country to form the basis of a national standard.

Without this base information the group are currently unable to conclude whether there would be benefits in the development of such a standard.

The need for external Public Address Systems at large out of town shopping complexes
Due to time constraints the group have been unable, as yet, to address this issue.

Developments in siren systems
Modern siren systems offer:

• Low current draw and are therefore able to operate from integral batteries following disruption of utilities

• Radio control and therefore they are independent of land line/utilities

• Pre-recorded voice chip messages and live broadcast if required

• Full time conditioning monitoring thus reducing the need for live testing

• System controllers that can initiate individual, groups or all sirens

They can also form part of an integrated system using external sirens and small alerting receivers for the inside of buildings.

Recent UK siren system developments

Severnside Warning System
Following a number of incidents in the Avonmouth area a consortium consisting of:

• Local Authority Representatives Councillors
• Local Industry (Contributors)
• Bristol City Council (Emergency Planning)
• Emergency Services Representatives
• Bristol Port Authority
• Others appointed from time to time

Formed a charitable trust entitled the "Severnside Siren Trust" to develop a warning system for an area comprising:

• 8 COMAH sites plus many other chemical and industrial complexes.
• An area of 105 Sq. Km.
• Residential Population of 4500
• Working Population of 10000.

The system commissioned was based on similar systems installed in Denmark, Sweden, Holland and several other countries.

It utilises nine sirens and the inaugural public test of the system took place on the 12th April 1999.

CORUS Teesside Warning System
A similar system to that in Severnside was commissioned in Teeside on the 21st November 2001.

The CORUS site is twelve Sq. Km. in size and located along the Mouth of the Tees with three on-site mills. One unit is over 1 mile long with a high ambient noise level that had to be included in the warning plan.

The on site working population is circa 4000 - including transients. The warning system utilises 10 radio controlled siren units with a visual indication (flashing strobe lights) to cover the outside area and the internal areas with high ambient noise levels.

Recommendations in respect of sirens and public address systems
The NSC recommends that:

• A national database of locations where sirens are used to warn the public be developed. This should include information on the type of siren, warning tone and instructions given to the public on what to do when the siren sounds.

• The NSC utilises the information in the database to decide whether there is a case for establishing a UK standard for siren systems

• The need for external Public Address Systems at large out of town shopping complexes form part of the continued work programme of the NSC