Fire safety in road or rail tunnels is of paramount importance in avoiding potential loss of life
Fire safety in road or rail tunnels is critical in avoiding potentially disastrous incidents

Roger Wilton, Assistant Technical Manager of the Fire Industry Association (FIA), explains the challenges of preventing underground fires.

Fires in tunnels tend to make headline news, largely because of the potential loss of life that such an incident presents. At the turn of the new millennium three catastrophic fires in as many years ensured that tunnel protection became a real focus on the fire safety agenda.

In 1999 the Mont Blanc tunnel fire, probably the most well known of the three, resulted in 39 deaths when a Belgian transport truck caught fire, resulting in temperatures of 1,000°C and taking some five days to cool sufficiently for crews to enter the tunnel to begin three years of repairs and significant enhancements of the safety equipment and procedures.

This was followed in November 2000 by the Austrian Kaprun funicular tunnel fire which killed some 155 people as they headed for the pistes in a popular ski area some 350 kilometres to the west of Vienna. 

Then, in October 2001, the St Gotthard Tunnel in Switzerland, the third longest road tunnel in the world, saw two lorries collide to create a fire that killed eleven people. Tunnel fires have, of course, occurred before and since but three such major incidents in such a short timeframe highlighted very clearly the dangers of tunnel fires and the need to recognise the specific challenges that tunnels present in terms of fire safety engineering.

When construction work is undertaken in an underground location, the project plan for safety and in particular fire safety needs to address the extra risks associated with work in an area that, by definition, will have limited means of escape. The area will inevitably be one in which ventilation will be restricted. Lighting will also be a prime consideration.

Risk Assessment

A comprehensive and dynamic fire risk assessment document is essential for creating a successful fire safety strategy

 

Managing an emergency successfully is a matter of planning, having the correct equipment in place and employing an effective maintenance programme to ensure that the equipment works when required. The first essential is a risk assessment undertaken by a competent person.

Particularly during the construction phase of a project, the risk assessment needs to be a dynamic working document that changes as the work progresses. The ownership and authorship of said document needs to be one of the project manager’s prime tasks. It should link to a project fire and safety strategy document that indicates how the risks identified are being managed and how the process for emergencies are to be handled.

For example, if a risk from mechanical plant operating in the underground location is identified, the strategy may require that a mechanical plant containing volatile fuel or gas be fitted with an automatic fire suppression system and that during operation a specified number and type of portable fire extinguishers be available. The strategy document may also require that persons operating the equipment undertake specific training on the use of fire extinguishers.

Fire risk and fire strategy are the tools of the trade for driving down financial loss and reducing project delay.

A fire risk assessment follows a logical pattern

  • Identify fire hazards
  • Identify people particularly at risk
  • Evaluate, remove, reduce and protect from risks
  • Record, plan, instruct, inform and train
  • Review the plan

Specific fire risks in construction work underground are determined on each site. However, all such work will need to consider the following when producing a proposed fire strategy:

  • Difficulties in providing means of escape.
  • Enclosed environment ventilation issues.
  • Access for emergency services.

 

Whilst underground tunnels are being constructed, all fire hazards must be identified and the correct fire safety measures taken
Whilst tunnels are constructed, fire hazards must be identified and correct fire safety measures taken

During a construction project the first requirement of the risk assessment is to identify the fire hazards. This may be one of the most challenging problems as identifying what will burn and is potential ignition risk is linked to use and the experience of the user.

The hazards will change as the construction progresses. The risk will increase as initial construction gives way to first and second fix. The materials used in construction are often delivered in flammable packing to prevent transit damage. A management process for safe storage and for efficient removal of packaging materials is required. The need for fire extinguishers suitable for Class A fires (those involving solid materials, such as paper wood or textiles) is apparent.

The construction programme can be part of the risk control programme. For example, the completion of enclosed stair routes before other work proceeds can help address safe escape routes. Early provision of a ventilation system will assist in control of the environment to allow escape. Control of the area by a ‘permit to work’ system and a temporary fire alarm system can assist in the risk reduction process.

All of the above underlines my assertion that the risk assessment needs to be a dynamic working document that changes as the work progresses.

The fire protection of an area can be enhanced by using heat or smoke detection. The services that a tunnel normally carries can form part of the detection. For example, fibre optic cables can form the sensor for a linear heat detection system that can provide precise location information. As with many fire situations, providing warning at the earliest possible point is the goal and identifying the source of a fire is a significant factor in this process. CCTV systems can also provide a smoke detection output as well as supplying video information.

From construction to use

Once the construction phase is complete the elements of the operation of a tunnel need to be built into the equation. The risk and the fire load - that is the amount of combustible material in the area or passing through - need to be recognised and the fire protection measures employed accordingly. The requirement for fire fighting systems and the location of portable fire extinguishers will depend on the use to which the structure will be put.

If personnel are normally located within a given area of the tunnel, the system to alert them to potential danger needs careful consideration. The variety and versatility of voice and message sounders is an important factor here, with voice-based messaging increasingly being used to provide a precise instruction for an evacuation that is not available from a purely tone-based sounder.

Rising to the challenge

 

Both Europe and the USA are conducting ongoing research into methods of more effectively reducing the threat of underground tunnel fires

Tunnels provide their own unique fire safety challenges, whether during the construction phase or when the tunnel is actually in use. This article has only scratched the surface of what needs to be considered. Extensive research is ongoing, both in Europe and in the USA, to find methods of further reducing the threat of fire. This is not only in terms of fire prevention, testing the relative strengths and, importantly, the weaknesses of different fire detection technologies, but also in providing the means for safe evacuation to prevent the tragic loss of life which the three incidents highlighted at the outset demonstrate only too well.

Roger Wilton - Assistant Technical Manager - Fire Industry Association (FIA)

Share with LinkedIn Share with Twitter Share with Facebook Share with Facebook
Download PDF version Download PDF version

In case you missed it

In A Busy Wildfire Season, Researchers Seek New Approaches
In A Busy Wildfire Season, Researchers Seek New Approaches

It makes perfect sense that a horrific wildfire season would come in the year 2020 on the heels of a pandemic. Dozens of major fires burned across North America in September, including 85 large uncontained fires and six contained fires across 12 states. Active fires have burned more than 3 million acres already, and 41,417 fires have burned almost 5 million acres year-to-date. The severity of the wildfire season is on track to surpass the 10-year average. Better understanding wildfires Global warming is often mentioned as a contributor to the wildfires, but there are other factors, too. Increasingly, researchers are looking to apply new approaches in address the risk of wildfires. They include tools such as deep learning and artificial intelligence (AI) to better understand wildfires and to control their intensity. The model could be used to reveal areas of greatest risk for wildfires A new deep learning model uses remote sensing and satellite data to trace fuel moisture levels across 12 Western states, in effect tracking the amount of easily burnable plant material and how dry it is. After additional testing is complete, the model could be used to reveal areas of greatest risk for wildfires and to plan the best areas for prescribed burns. Led by a Stanford University ecohydrologist, the research was published in the journal Remote Sensing of Environment. Recurrent neural network The model uses data from the U.S. Forest Service’s National Fuel Moisture Database, which amasses plant water content information from thousands of samples. Using a ‘recurrent neural network,’ the system leverages the fuel moisture data to corroborate measurements of visible light and microwave radar signals from spaceborne sensors that are tasked with estimating fuel moisture measurements. Newer satellites with longer wavelengths allow sensitive observations about moisture content deeper into the forest canopy. Estimates from the model are used to generate interactive maps that fire agencies may one day use to identify patterns and prioritize wildfire control estimates. Researchers are also working to analyze the impact of better and more efficient firefighting on the size and frequency of wildfires. The theory goes: When firefighters extinguish smaller vegetation fires, a consequence is the creation of an environment where wildfires are larger and/or more frequent. Natural cycle of regeneration Older woods will naturally catch fire from the sun’s heat to make way for fresh growth The theory is based on the premise that wildfires play an essential role in the periodic regeneration of forests. Older woods will naturally catch fire from the sun’s heat to make way for fresh growth. However, more efficient firefighting can disrupt the natural cycle and, along with global warming, aggravate the broader likelihood of larger and more frequent fires. Researchers at the WiFire Lab in California and the University of Alberta in Canada are using artificial intelligence (AI) to analyze the environment and provide recommendations for prescribed burns that can save some parts of the forest without interfering with the natural cycle of regeneration. Providing early warning of wildfires Equipment operated by Pacific Gas and Electric (PG&E) caused 2018’s Camp Fire, the most destructive wildfire in California history. Because of the threat of sparking a wildfire, PG&E this year shut off power to 172,000 customers in Northern California on Labor Day weekend, for example. A concern is the threat of winds tearing down power line or hurling debris into them. Southern California Edison (SCE), another utility, warned that about 55,000 customer accounts could lose power. California utilities SCE, PG&E and San Diego Gas and Electric are helping to fund a network of ALERTWildfire video cameras in California that will help to provide early warning of wildfires. Video cameras keep watch throughout five Western United States to provide early warning, and the number of cameras is growing fast.

Should Firefighters And First Responders Use Face Masks?
Should Firefighters And First Responders Use Face Masks?

Should firefighters and other first responders be exempt from requirements that they wear face masks to prevent spread of the novel coronavirus (COVID-19)? The City Council of Portsmouth, New Hampshire, seems to think so. They are proposing an amendment to exempt first responders from complying with the city’s face mask ordinance. Amendment to Exempt first responders from face mask rule Specifically, the proposed amendment states, “Exempted from the requirements of the ordinance requiring wearing of face coverings include law enforcement personnel, first responders or other workers, who are actively engaged in their tasks, if wearing a face covering may hinder their performance.” The Centers for Disease Control and Prevention (CDC) recommends that everyone wear masks in public settings The Centers for Disease Control and Prevention (CDC) recommends that everyone wear masks in public settings, especially when social distancing cannot be maintained. The CDC does not specify a need to exempt first responders. However, there is a possibility that a mask could interfere with the work of firefighters or first responders, especially when they are performing tasks that require physical exertion. Face masks can inhibit communication among first responders Face masks, covering the mouth and nose, could also inhibit communication by muffling sound and obstructing facial expressions. Obviously, communication is of paramount importance for firemen working as a team in an emergency, or when a first responder is seeking to give clear directions to the public. The issue of face masks has been inexorably entwined with the well-being of first responders, since the beginning of the COVID-19 pandemic. Early on during the infection spread, health officials dismissed face masks as a tool to avoid spread of the disease. They said that the masks were ineffective at preventing community spread and that, supplies of personal protective equipment (PPE) needed to be conserved for health professionals and first responders. Importance of face masks in controlling spread of COVID-19 However, the early advice was completely reversed in late March 2020 and masks have been advocated ever since. A mask, worn by an infected individual, reduces the dispersion of virus-laden droplets that spread the disease. Now, experts contend that any type of mask, including cloth or paper, can help to reduce spread of the COVID-19 virus. Expanding the use of masks to include those that are not conformant with the N-95 classification effectively eliminated any concerns about supply and helped to make the widespread use of masks the norm. To some extent, however, mask usage in the United States has been politicized and some see the requirements as an affront to liberty. Need for wearing face masks in public Masks are a useful preventative measure for firefighters working together in a communal area Fire and emergency departments face the same challenges as other businesses and institutions, as they seek to remain safe in a communal workspace. Masks are a useful preventative measure for firefighters working together in a communal area or when training or resting. Wearing masks in public also allows departments to model best practices and promote a positive perception of the department to the public. Disciplined use of face masks demonstrates unselfishness and respect for others. It communicates professionalism and concern for the greater good. Masks go a long way in saving lives of first responders Perception may also be an issue when it comes to the choice of masks, which become a de facto part of a uniform. Masks with political statements should be avoided, for example. Considering that dozens of American fire and EMS members have died of COVID-19 infection, since March 2020, the use of masks is another way that firefighters can work to save lives. However, sufficient flexibility is needed so that the use of masks does not interfere with other lifesaving duties.

What Are the New Trends in Firefighting Equipment?
What Are the New Trends in Firefighting Equipment?

Equipment is an important element in fighting fires, and in keeping firefighters safe. But what new needs are driving the development of equipment? How can equipment expand its role in fighting fires, or in managing building occupancy and traffic flow for that matter? We asked our Expert Panel Roundtable: What are the new trends and opportunities in firefighting equipment?

vfd