Preserve evidence and support investigation: Transport incidents

Control Measure Knowledge

This control measure should be read in conjunction with Preserve evidence for investigation


Only personnel required to deal with the incident should access the site. Movement of modes of transport, and any components of the transport network, should be kept to a minimum. Personnel should be aware of the need to maintain and secure the scene.

The need to investigate should not affect bringing any incident to a safe and satisfactory conclusion, or interfere with incident objectives and priorities. There may be an opportunity to scale down incidents to allow investigators into safe areas, but this should not affect ongoing operations and scene safety should remain a priority. Nominating safe paths to and from the scene should assist in preserving evidence.

As part of the investigation process, personnel may be asked for witness statements; these should be given as soon as possible. Debriefing of any transport related incident may form part of the investigation and should be recorded.

Early liaison to fulfil the requirements of the statutory investigation team is required. However, the control of the scene should not interfere with any lifesaving activities or fire and rescue service statutory duties.

Although it is primarily a police function to secure an accident site, personnel need to be aware of the reasons for its implementation and consider how their actions may affect any subsequent investigation. Unauthorised access to the site should be prevented as vital evidence can be destroyed by walking or moving equipment over it.

Avoid moving functional switches and levers from their pre-accident position, as this can provide negative and confusing information. Efforts should be made to preserve vulnerable evidence, or evidence that may deteriorate. Unauthorised personnel may contaminate the scene or be carrying sources of ignition, unaware of any potential hazards involved.

The positions of fatally injured casualties are extremely important for identification purposes and to help establish the cause of an accident. The removal of bodies should only be carried out under the direction of the police or statutory investigation team.

However, removing the bodies before the arrival of investigation teams or medical teams may be necessary to rescue casualties, or to prevent bodies being destroyed by fire or other hazard. If this is the case, the position of the body and its location should be noted, labelled if possible and reported to the investigation team.

Rescuers who have moved bodies should be questioned, and a statement should be made as soon as possible after the incident to gain the most accurate information. Whenever possible, an officer should be appointed to map out the location and position of bodies. Consideration should be given to the potential areas in which bodies may be found, as the type of incident may result in a wide distribution of them. Bodies may need to be moved very carefully, as further damage may destroy vital evidence for identification and cause of death.

It may be useful for photographs or video to be taken of the wreckage, the accident site and the position of the bodies. This can also assist in debriefing purposes.

Most people will carry personal effects and papers, for example, passports, driving licences and tickets. The position of these documents and personal effects of passengers and crew, along with any documents and papers at the incident site, may help the investigating team. It is important to leave these items in place; if they need to be moved, their location and position should first be recorded.

It is important to control the number of people allowed on the incident site so that evidence such as personal effects are not disturbed, or are disturbed as little as possible. When the situation permits there should be a careful withdrawal of all non-essential personnel and equipment. If casualties or bodies are moved, great care should be taken to ensure that any item that is adjacent is recorded or moved with the casualty or body.

Any items that fall from the casualty or body whilst being moved should be collected, recorded and kept with the casualty or body if possible, as it may prove to be a means of identification.

Ideally wreckage should not be moved or disturbed unless for rescue or safety. If wreckage, or any part has to be moved before the investigation is complete, a record should be made of the location and position of all the parts, taking care to preserve any evidence that may be important to the investigation, such as the position of controls, levers, switches, pressure gauges, air systems and dials.

There is the potential for personnel to cross-contaminate an accident scene; this could be through blood injuries to personnel, via personal protective equipment (PPE), the surrounding environment, or fire and rescue service vehicles. If personnel believe that any cross-contamination has occurred, this should be recorded and reported to the relevant accident investigation team.

Once rescue and firefighting operations are complete, the responsibility for the security of an accident site, the wreckage, its contents, personnel and other effects will be that of the police or the statutory investigation team. Post-incident, the scene should be handed over to the statutory investigation team, highlighting the hazards and any control measures still in place or required.

Roadways incidents

All serious road traffic collisions are subject to a police investigation. In more serious road collisions, particularly with fatalities, specialist investigation teams try to reconstruct the scene, position, speed and condition of the road vehicles involved immediately before the accident. Personnel need to be aware of, and respect, the needs of the investigating officers completing such investigations.

The position of road vehicles, along with any debris, are vital evidence in any investigation and movement of them should be kept to a minimum. Washing down of any road surface should not be carried out unless authorised by the investigating team.

Wherever practicable, tyre marks should be preserved. Correct positioning on initial attendance may prevent fire appliances having to be resited, therefore reducing the volume of tyre marks at the scene. Fire and rescue service vehicles should not be parked close to the road vehicles involved in the incident.

The condition and inflation pressure of tyres may give vital clues in the accident investigation. Deflation of tyres by personnel to achieve ‘flat tyre blocking’ should only be carried out in exceptional circumstances if all other methods of vehicle stabilisation are not appropriate. The police should be informed if this procedure has been carried out.

In many instances, vehicles involved in serious road accidents are taken for examination to establish their mechanical condition before the accident. In doing so, vehicle batteries need to be reconnected. It is therefore important that, wherever possible, personnel disconnect battery terminals using spanners rather than cut through battery leads when making vehicles safe.

If a vehicle is fitted with a tachograph, the equipment and charts should be left in place for the investigating officer.

Strategic Actions

Tactical Actions