Transport for NSW – Risk Assessment for Dangerous Goods Through Tunnels


The standardisation of Risk Assessment for Transport of Dangerous Goods (DG) through tunnels project develops a critical risk assessment methodology that facilitates a quantifiable hazard analyses process for the transportation of dangerous goods through tunnels. The risk assessment is comprehensive and considers application in multi-modal tunnel including road, rail, metro and pedestrian tunnels.

The developed risk assessment standard will provide decision makers with the means to identify potentially significant risks to the community, environment, or infrastructure that may occur in the case of loss of containment of freight. Transport for New South Wales (TfNSW) divisions: Regional Outer Metropolitan, Safety Environment and Regulation, Infrastructure and Place and the Greater Sydney have collaborated in formulating an innovative best practice approach to conduct an independent quantified risk assessment. The methodology assesses and analyses the risk associated with Dangerous Goods freight transportation with the aim to mitigate the occurrence of serious incidents involving DG freight that may cause loss of human lives, environmental degradation, tunnel damage and transport disruption whilst balancing the needless banning of dangerous goods from tunnels that may create unjustified economic costs.

Our work used best practice principles defined in the TfNSW Asset Management Framework to balance cost, risk, and performance to demonstrate the desired customer-focused safety and value outcomes through the establishment of the risk assessment methodology.

Project Description

A serious incident involving DG in a tunnel can be of significant cost in terms of loss of human lives, environmental degradation, tunnel damage and transport disruption. Conversely, needless banning DG from tunnels may create unjustified economic costs. Moreover, such a ban might force operators to use more dangerous routes, such as densely populated areas, and thus increase the overall risk to the public.

Several previous studies over previous years had been attempted in TfNSW tunnel projects as a part of the design and evaluation process to transport the DG. However, those studies were insufficient to drive a robust decision-making process within TfNSW.

There is no current state or national standard for risk assessments associated with the transport of DG through tunnels. As new tunnels in NSW are being designed to allow for DG vehicles, there is an increasing need to implement regulations around DG passage, which is the responsibility of the relevant road authority (according to the Roads Act 1993), Transport for NSW, in this instance.

Following the intensive review of the previous studies and evaluation of the project scenario, the Tunnels team in Asset Management Branch (AMB), under the direction of Director Engineering, made the decision to develop a multi-modal standard for the risk assessment of DG through tunnels considering the best practice of Asset Management principles of an outcomes-based approach and safe systems in line with TfNSW Asset Management Framework to guide this work. Such a decision should get assurance through a systems and safety engineering approach for the tunnel design and operational procedures by considering the risk and consequent design based on the so far as is reasonably practicable (SFAIRP) framework.

While developing the standard, AMB Civil team have been working in the risk assessment of DG through tunnels in TfNSW projects. The practical experience of DG risk assessment in those projects have been used to finalise this standard.    

What we did

The DG risk assessment was completed successfully rigorous focus on human centric safety principle through a systems and safety engineering asset management approach. The process involved adapting quantitative risk assessment methodologies and frameworks from the major hazard industry, purchasing an international modelling tool, and ensuring a methodology of asset management that enables decision making with engaged stakeholders.

The focus of completing the quantified risk assessment is outlined below

  • Provide an independently verified study of work
  • Quantification of risk (i.e. likelihood and consequence)
  • Provide an absolute level of risk that can be used to inform internal and external stakeholders of the risks associated with DGVs through tunnels
  • Provide comfort to communities and industry
  • Potential to demonstrate innovation in design
  • Confirm the effectiveness of some mitigation measures as part of an SFAIRP demonstration

Several scenarios were developed to assess the different types and quantities of DG vehicles to assist with informed decision making to future proof the design and operation of any tunnel projects in NSW. The method considers the risk from DG vehicles travelling through alternative on-surface routes. From the assessment, the detailed design could proceed with the appropriate safe design studies and fire and life safety studies to determine the fire and smoke protection requirements for the tunnels as part of the demonstration risks are eliminated or reduced SFAIRP.

How we did it

The DG risk assessment project was developed successfully under a very tight timeframe and the management of the project was underpinned by defined work sprint packages and an innovative solution that achieved the desired outcome. This couldn’t have been possible without the rigorous focus on human centric safety principle through a systems and safety engineering asset management approach.

In addition to the technical analysis required for this project, a key objective of this project was also to collaborate with all relevant internal stakeholders and ensuring all interested stakeholder perspectives, including current major tunnel projects in NSW are addressed and satisfied in the guidance provided for the Dangerous and Goods. The development of the risk assessment methodology will establish best practice for dangerous goods risk assessment that will be applied to future tunnel projects. The Extensive consultation process as well as the application of the risk methodology in current tunnel projects validates the established process.

The team led by the Director of Civil Engineering Infrastructure prepared a comprehensive project brief and managed the project to meet the short timeframe aligned with the current tunnel projects so application of the process in projects can be assessed such that the client’s requirements are established. As part of this initiative, the senior management team will be provided with clear recommendation for decision making with facts and figures based on the modelling with the available tools, scientific analysis and risk demonstration of eliminating or reducing risk SFAIRP.

Why we did it

There are no national or international standard currently available considering SFAIRP to decide for the transport of Dangerous Goods (DGs) and minimum design requirements to support this decision.

This study concluded that transit of DG vehicles through the tunnels in NSW needs to be assessed against the risk associated with DG vehicles travelling through on surface routes.  The outcomes of the project contribute to environmental and societal benefits, optimising economics. The associated benefits will benefit both directly and indirectly for current and future infrastructure projects across Australia.

This study showed that transport of DG through NSW transport tunnels may slightly increase CAPEX and OPEX compared to the current practice in tunnels, however, it provides significant economic benefit by saving travel time costs; enhancing the safety measures to mitigate the risks to the surrounding community and its customers; addressing the demands for the transformation of the transport; and ultimately contributing enormous environmental and societal benefit both directly and indirectly for this and all future infrastructure projects across Australia. 

Our work from the perspective of Asset Management Principles

The development of the dangerous goods through tunnels risk assessment standard stems from this core asset management principle where careful consideration is given to the residual risk for transport tunnels from the haulage of dangerous goods through the tunnel against the optimal function of the tunnel to perform as an efficient and safe route for the transportation of goods and people. The performance of the tunnel operation is optimised given the acceptability of the risk in terms of the reliability, availability, maintainability, and the supportability of the asset. Cost is an important consideration in the development major infrastructure projects such as tunnels in monetary value, however as part of the risk assessment, the cost is quantified as the effect on human life in the case of the occurrence of an incident.

The asset management principles underpin the core risk assessment methodology.

Output focus

The risk assessment methodology is developed based on the clear output focus on the design, construction, and operation of safe and efficient transport tunnels in NSW. The project will ensure that effective decisions are made to mitigate chances of risk in the case of loss of containment of dangerous goods along with ensuring that vehicles carrying dangerous goods have efficient and safe routes to transport essential DG for the operation of society. The mitigation of potentially unsafe and costly damages from incidents involving high risk dangerous good freight provides value to the community as users of the tunnel and prolongs the longevity of the asset.


The risk assessment methodology will guide decision makers to incorporate consideration of risk associated with the transportation of dangerous goods in technical and financial decisions to optimise the safety and economic factors of the tunnel projects. The risk assessment recognises and strongly underpins the core capability of the tunnel asset is to transport goods and people safely and efficiently. This is a based on a careful compromise between performance and risk where decision makers will be able to balance capital costs with long term economic benefits of the tunnel project and enable risks to be identified earlier in the project.

Level of Assurance

The risk assessment methodology provides guidance that will provide assurance that all tunnels in NSW across projects and modes will be able to provide as safe as far as reasonably practical transport infrastructure to the community through the undertaking of a risk assessment on dangerous goods through tunnels. The comprehensive risk assessment of dangerous goods will provide a means to quantify risk associated with the possible loss of containment and provide users and asset owners with the confidence that careful consideration has been given to the likelihood of incidents and the associated cost and consequences.

Learning Organisation

The risk assessment methodology is developed based on lessons learnt and experiences from past and current tunnel projects in NSW. The methodology has undergone several iterations and critical evaluation to ensure that it is reflective of the true risks and performance that may be encountered in projects. The approach is an innovative method that will be consistently revised and improved in response to developments in risk assessment for dangerous goods through tunnels and be a leader in risk evaluation for infrastructure projects in the future.

Specific Contributions

“Our team used best practice asset management principles in our collaborative approach to evaluating the risk assessment dangerous goods through tunnels . The team was focused on balancing cost, risk, and performance to demonstrate our desire for customer-focused safety outcomes.”

— Diana Zagora, Director Civil Engineering Infrastructure

Our approach to the project is industry leading, entailing deep collaboration to improve and embed Asset Management principles and behaviours for a robust methodology to remove uncertainty around decision making to transport DG goods through the tunnels.

General Comments

While the project has delivered extensive value so far, we are proud to be committed to this work on a long-term basis. As the journey continues, additional innovations will be embraced to articulate value for DG through tunnels as we work towards achieving our Asset Management goals:

  • to plan for a transport system that meets the needs and expectations of the public and customers
  • to promote economic development and investment
  • to provide integration at the decision-making level across all transport modes
  • to promote greater efficiency in the delivery of transport infrastructure projects 
  • to provide safe and reliable delivery of transport and productive freight services

Transport for NSW is committed to delivering transport which contributes to economic prosperity and social inclusion in an environmentally responsible and sustainable manner, and a vision to create a NSW where every journey is people and planet positive.

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