by CSIRO

You might use them to zip under the city, cross the harbour or pass through a mountain – tunnels are a major part of Australia’s road and rail infrastructure. With lengths of up to nine kilometres, which is the longest in Australia, they require precise planning, engineering and ongoing maintenance to keep users safe and avoid the types of disasters we only want to see in movies (because let’s face it, no one wants to end up as Sylvester Stallone in Daylight).

At CSIRO, our Infrastructure Technologies teams work hard to provide specialist services to managers of this key type of national infrastructure.

From working with the companies that paint the lines on the road, to those that install and manage the ventilation, CSIRO is involved in ways you may never have imagined.

Conditions underground present unique challenges compared to those on the open road, which makes the safety measures of tunnels of utmost importance, particularly those which prevent accidents or fire.

Every single element of installed safety systems must undergo meticulous testing to ensure that they work as designed, continue to operate over time, and are ready to perform to their exact specification in the event of an emergency.

The tests undertaken by CSIRO on products and systems installed in tunnels cover structural fire performance, smoke management and ventilation, fire detection and alarm transmission, painting, speaker systems and often-ignored road markings.

It’s getting hot in here

Fire is one of the biggest threats to the safety of occupants of a tunnel, but the next time you drive through one, have confidence knowing that in the unlikely event of a fire, every safety element has been thoroughly considered.

High temperatures affect each material in different ways, but in a tunnel, it’s vital that the structure of its linings – the walls and ceilings that define the tunnel – are not adversely affected by fire. Road tunnels are tested to ensure that their, typically concrete, linings remain structurally sound and in place, while withstanding temperatures of up to 1350°C for many hours.

During testing, the concrete structural elements of the tunnel are exposed to a gas-fired furnace, which represents the intensity of an environment full of burning hydrocarbon (petrol), while being continuously checked to ensure that the lining will maintain its integrity during a car (or worse, a petrol tanker) fire inside.

Breathing easy

Adequate ventilation is crucial to ensure that safe conditions are maintained while a tunnel is in operation. In the event of an underground fire, it is very important that ventilation systems can clear large volumes of smoke while tunnel users evacuate.

CSIRO tests tunnel ventilation systems using largescale smoke generators, which produce and direct heated smoke to simulate the buoyancy and flow characteristics of real fires.

During these tests, CSIRO staff can look more like firefighters than engineers and scientists, outfitted with hi-vis protective clothing, helmets and breathing apparatus to replace the white coats usually associated with CSIRO’s experts!

Triple zero heroes

Fires require rapid response. In the event of an emergency, the fire brigade and tunnel management systems are automatically notified of incidents through a series of advanced smoke and heat detection sensors and control systems.

While these systems may quietly monitor the tunnel year after year, they must raise an alarm within seconds of detecting a fire. CSIRO operates Australia’s only laboratory which tests and assesses fire detection systems, testing many types of detectors to ensure that they respond to fires, and also the interconnected control systems which transfer the emergency information to the fire services.

Alerting drivers

In case of an emergency, tunnels include a network of occupant warning systems, emergency sounders and loudspeakers to alert tunnel users with safety warning messages to assist with safe evacuation.

Loudspeakers and sounders are subjected to an extensive acoustic and durability test program, with speakers exposed to heat, cold, humidity, corrosion, shock and vibration. They are also tested in CSIRO’s anechoic chambers to ensure that their audio performance remains high so that they can produce messages with good speech intelligibility.

CSIRO staff also mathematically model the time taken for users to evacuate tunnels once they hear the emergency message.

Watching paint dry

While most don’t give it a second thought, road markings are a critical life safety component of the transport system. The coatings and reflective materials used in road markings are tested for both performance and durability over time.

CSIRO operates an accreditation scheme for organisations that apply road markings and individually audits each accredited company to ensure that their processes and systems enable the tested coatings to be applied correctly.

And, there’s a lot more to a white line than one may imagine. Our paint and coating accreditation programs write and manage hundreds of technical specifications specifying the attributes and requirements for these essential coatings, covering everything from light reflectance to how long they take to dry.

Don’t panic

CSIRO doesn’t intend for the above discussion of emergencies and disasters to cause concern. Although car accidents will happen from time to time, Australia’s road and rail tunnels have comprehensive safety systems, which allow all of us to enjoy the benefits of a quick trip from A to B without any worries.

Hundreds of Australian companies and thousands of talented experts deliver safe tunnel infrastructure, and CSIRO is proud to support them with the scientific services they need to do this important job.

If you are interested in any of the diverse range of testing and consulting services at Australia’s national science agency, CSIRO, please contact the Infrastructure Technologies team at https://research.csiro.au/infratech/

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