ARTU

ARTU - Tunnel Risk Analysis

ARTU is a software tool for risk assessment in tunnels, whether newly built or already in operation.
Risk analysis makes it possible to quantify the “societal” risk, expressed as the expected number of fatalities per year.
The analysis is required when a tunnel does not meet the regulatory requirements set by national standards. This approach allows to evaluate how non-compliances or “special” characteristics of a given tunnel impact its risk profile relative to an acceptability range (the ALARP interval) defined by the regulator.
ARTU can be used both to support the preparation of safety documentation and during the design phase to evaluate, in relation to the risk profile, the effects of design or operational changes and/or alternatives.

1. Regulatory context

Following the European Parliament Directive 2004/54/EC, risk analysis has become an integral part of the design and management of tunnels.
While a tunnel behaves similarly to any other road segment in the case of a traffic accident, it becomes a critical environment for the preservation of human life during a fire event, due to its confined nature. Tunnel fires can generate life-threatening conditions in extremely short timeframes as a result of toxic smoke accumulation, rapid visibility loss, and sharp temperature increases that directly affect user evacuation.
Within this context, the ARTU software was developed by Cantene in collaboration with the Fire Safety Engineering Department at Lund University.
ARTU combines a probabilistic approach with advanced physical modeling to quantify “societal” risk — that is, the likelihood that a tunnel fire could result in casualties among users.

2. An innovative methodology

The innovative aspect of ARTU lies in its ability to combine a probabilistic approach —used to evaluate a very high number of fire scenarios— with deterministic assessments that describe in detail the interaction between combustion products and the people involved in the event.
ARTU probabilistically defines the set of assumptions underlying the scenarios to be analyzed: the location and magnitude of the fire, the size of the user queue, and the functioning or failure of active protection systems. For each scenario, it performs fluid-dynamics and evacuation analyses in order to evaluate the impact of the interaction between users and combustion products through the FED metric.

3. The multizone model

One of the signature features of ARTU is its use of a multizone model to study the evolution of combustion products.
Developed in collaboration with Lund University, the multizone model enables the representation of complex phenomena such as smoke stratification and back-layering.
Depending on the characteristics of the tunnel, ARTU applies either a 1D model or the multizone model within a multiscale framework.
This ensures a balance between accuracy and computational speed — one of ARTU’s key strengths.

4. ARTU in numbers

Number of tunnels: 30

KMs of tunnels: 50

Number of science publications: 2

Attendance to international conferences: 4

5. The advantages of ARTU in the scenario of tunnel safety

Integrated approach
Combines probabilistic and deterministic approach within a single platform.

Computational efficiency
Enables to develop comprehensive analyses while keeping calculation times manageable.

Accuracy
On one hand, multiscale analysis allows for accurate simulation of the evolution of combustion products. On the other, evacuation modeling reproduces the movement of users during self-evacuation.

Reliability
Continuous validation against literature data, through full-scale tunnel tests at the Fire Safety Engineering Department of Lund University, and results from 3D CFD simulations.

Design tool
Supports designers and concessionaires by providing a tool for comparative analysis of potential design alternatives.