Long closures following serious fires in the Mont Blanc, Tauern and Gotthard tunnels had a major economic impact on the countries affected, as well as on surrounding regions. More minor, but frequent incidents, such as vehicle accidents, breakdowns and spills, also cause delays to the travelling public. Tunnels are normally used to overcome obstacles and there is frequently no convenient alternative route, so incidents can quickly lead to widespread congestion.

Delays continue after the emergency phase until the tunnel is reopened. Indeed the post-incident recovery phase may last longer than the emergency phase. It comprises activities such as: cleaning and clearing up, disposal of waste, inspections, repairs, refurbishment, traffic management and keeping the public informed of progress. These activities may start during the emergency phase, provided priorities such as saving life, containing the incident and preserving evidence are not compromised.

It is important to minimise delays to road users by returning the tunnel to normal working as soon as possible, whilst limiting adverse environmental impact and undue expenditure. There are safety benefits too, as stationary or queuing vehicles themselves increase the risk of further incidents.

Therefore the Highways Agency (HA) commissioned TRL to advise on how to achieve best practice in post-incident recovery. The report[1] contains lessons learned from past incidents, a review of current practice, an approach for achieving best practice and much practical advice from experienced tunnel operators. This article highlights the main findings.

Lessons from past incidents

Lessons were drawn from reports of previous incidents in tunnels worldwide. Incidents reported tended to be the major ones, and the majority involved fire. Whilst there was considerable interest in emergency issues, there was relatively little account of post-incident aspects.

Ironically, for recent major fires, the majority of time and money spent before reopening was in upgrading fire safety measures, rather than in simple re-instatement. For example, repairing the damage to the Mont Blanc Tunnel lasted a few weeks, whereas the tunnel was closed for nearly three years whilst new fire safety systems were arranged; and three months work after the fire in the Tauern tunnel included substantial improvements.

Structural integrity was rarely affected in the fires reported, thus tunnels could often be quickly re-opened even after a relatively serious fire. For example, the Holland Tunnel was re-opened only 56 hours after the fire started, despite the severity of the blaze. Even a severe fire in the Nihonzaka Tunnel (and incidentally in the Summit rail tunnel) caused relatively little structural damage.

However, mechanical and electrical systems were generally damaged more extensively than the structure, and were more expensive and took longer to repair. The supply time for equipment was often a critical factor. So reinstatement of these systems should be the major focus of recovery.

Experience indicates that post-incident recovery was facilitated by close co-operation between the tunnel staff, refurbishment contractor and material suppliers, especially when those familiar with the tunnel were involved. Training the tunnel staff in post-incident recovery, from fires in particular, was beneficial too.

Other factors that speeded recovery were: having auxiliary equipment, repair material and any unique components to hand; having easy emergency access to all areas of the tunnel and equipment; and deferring finishing works that are not vital for safety to night closures after the tunnel was opened.

The frequency and type of past incidents provide a basis for planning for future ones. TRL assembled records of the (mostly minor) incidents that occurred in fourteen UK road tunnels. Based on this information a range of generic incidents was proposed, shown in Table 1, together with a qualitative indication of their frequency.

Plans for post-incident recovery

Operating and emergency procedures for individual tunnels were reviewed. Although detailed plans were available or being developed at some tunnels, generally the post incident recovery was covered in less detail than the emergency phase. So, although experienced operators should be able to react to incidents based on their knowledge of the tunnel, it seems self-evident that having documented plans in place would enable them to respond better. This is important as knowledge is lost as operators and staff change.

Post-incident recovery is closely linked, and shares common objectives, with the emergency phase. So it is important that a tunnel operator’s emergency and recovery plans are made, tested and executed together, along with those of other stakeholders. This will ensure a rapid and integrated response to all incidents.

Operators should not simply reproduce plans from another tunnel, or delegate planning to an individual. The process used to derive plans is as important as, if not more than, the resulting plans. Preparing plans to deal with the generic incidents shown in Table 1 should cater for most incidents, but there also needs to be flexibility in dealing with events that do not conform to the expected pattern.

Flexibility will be achieved if all the systems of a tunnel are examined. The variety of ways that the various systems in the tunnel can fail or be damaged, the consequences of their failure and means of their repair should be considered. This approach will ask the ‘what if?’ questions and will highlight areas of vulnerability.

Minor incidents

The elements of a plan for dealing with minor incidents are shown in Box 1. An important aspect to be determined is the nature of the first response unit. Indeed a practical definition of a minor incident is that which the first response unit can deal with. The operator’s first response unit corresponds with Bronze in the national framework for emergencies. It will give a first-hand assessment of the incident from an engineering point of view, supplementing information from CCTV coverage, so enabling the operator to rapidly make correct decisions about mobilising further resources. Early action may also prevent a minor incident from escalating.

Non-tolled tunnels in the UK generally do not have staff at the tunnel or dedicated units. However, Incident Support Units (ISUs) from the area maintaining authority are equipped to set out emergency traffic management, clear debris and minor spills and make minor repairs of highway items, e.g. vehicle crash barriers. But they are not required to deal with abandoned or broken down vehicles, fires and hazardous materials. The police usually arrange for contractors to recover vehicles, and the fire service would attend fires.

In the toll tunnels, staff are trained and response vehicles are equipped specifically for the needs of those tunnels. Traffic patrol vehicles are used to tow light vehicles and are equipped to deal with small fires.

The benefits of providing response vehicles dedicated to particular tunnels, or for ISUs serving the tunnel to be equipped to tow light vehicles and carry spares for tunnel equipment, may be evaluated taking into account the user cost of delays calculated using COBA[2]. The analysis will depend on the circumstances of individual tunnels, particularly length, traffic volume and expected breakdowns, but dedicated vehicles may be justified in some cases.

The particular difficulties of recovery of heavy vehicles from tunnels should be noted. There may be insufficient headroom for partly raising a high vehicle. The righting of high vehicles or turning around of long vehicles may be impossible and there may be insufficient headroom for using a crane. In the Mersey Tunnel a large forklift truck is available for lifting of loads.

Avoiding temporary repairs saves subsequent expense and disruption, but they may be necessary to quickly re-open the tunnel because spare parts are unavailable or there is insufficient time for curing of material. A stock of basic repair material would include: proprietary bituminous pothole repair material (preferably with a long shelf-life), concrete repair materials, steel plates, and manhole and gulley covers.

Sufficient spares and consumables for equipment and systems should be kept to cope with a minor incident. But keeping more of items that have a long supply time may be necessary. Recently an over-height vehicle damaged a row of 117 lights in a tunnel. The tunnel was supplied with 150 spare lamps when new, and only 86, and at most 10 in one incident, had been used in the intervening 30 years. As many lights as possible were repaired, but some gaps remained for 12 weeks before more lights could be delivered. This incident illustrates the vulnerability of each system, especially equipment in the tunnel roof.

Major incidents

During the emergency phases of a major incident overall responsibility will rest with the police, while the fire service will take responsibility for fire related aspects. As the incident progresses into the recovery phase it will be appropriate to pass responsibility to the tunnel operator, although the police may have a continuing role in aspects such as traffic management and preserving evidence. The Environment Agency (EA) will provide advice and, if necessary, enforce environmental legislation.

Procedures for major incidents, in approximate order of priority, are shown in Box 2. They include a framework that guides key decisions and escalation procedures for mobilising greater resources.

Reports of past incidents showed the benefits of calling on contractors and suppliers who are familiar with the tunnel. Maintenance contracts would normally provide for emergency attendance, while for large scale works the tunnel operator might maintain a list of pre-qualified contractors. Recovery plans at one toll tunnel include a list of key contractors, suppliers and experts, with prepared e-mails and faxes to them.

In the Case of a fatal accident, access to the tunnel and clearing up may be delayed so that evidence is not disturbed until the police have finished investigations. Reports of past incidents showed that recovery was speeded when other work, such as mobilising personnel and equipment, proceeded during this time.

Methods of containing spills should have been agreed in advance with the EA. In most cases any run-off will collect in the tunnel drains. Drainage sumps are normally isolated and contaminated water later removed in a road tanker. Stocks of portable equipment and materials for dealing with pollution include absorbents, booms, drain blockers and pipe sealers.

Fires are normally extinguished with water, unless there is a liquid fire or it is suspected that a hazardous substance is present, in which case foam will be used. Spraying with water can disperse foam later. The fire service will not normally assist in general clean-up operations. However depending on time and resources they may offer assistance in washing down walls, etc.

The chemical composition of fire fighting run-off will vary and can be polluting. Measures for controlling this during fire fighting include substituting water jets with sprays or recycling firewater.

Documentation, such as as-built records, equipment manuals and risk assessments, should be kept up to date and readily available. For example at one tunnel information is stored in a database and linked to a 3-D model of the tunnel which is accessible remotely from a laptop computer.

A major tunnel incident will attract interest from the media, with calls for information about damage and disruption to traffic flows. The police normally take responsibility for this, but the operator should plan for providing information and giving interviews. Information on traffic disruption may enable drivers to divert and thus reduce the overall disruption to traffic. It is important to ensure that an ‘all clear’ is announced.

Finally it is important that all incidents (including minor) are recorded for statistical analysis and lessons learned are captured for future benefit. On completion of major incidents at least, actions taken by all the stakeholders should be examined and analysed and the results reported.


It is important to have in place post-incident recovery plans that have been developed and tested with the emergency plans and are integrated with the other stake holder’s plans. This will ensure a rapid, co-ordinated and integrated response to all incidents, with recovery considered from the first moments, whilst giving priority to emergency aspects. This will assist in reducing post-incident recovery time.


The author is grateful to the Highways Agency (project sponsor: Lionel Brown) for permission to publish this article. Fuller details of the study are available at www.trl.co.uk and www.highways.gov.uk. The views expressed in this paper are those of the author, and not necessarily of the Highways Agency.

Table 1: Range of incidents and likelihood of occurrence Box 1: Elements of a minor incident plan Box 2: Elements of major incident plan