HUMAN FACTORS - TUNNEL USERS

An adequate knowledge of human factors in the context of road tunnels optimises safety by acting in the direction of the user, the tunnel design and more generally, the organisation (tunnel operating body and emergency services). The focus of this chapter is on the interaction between the tunnel system and tunnel users; additional information is provided in the page "Human factors – Operators" regarding the interaction with tunnel staff and emergency teams.

The whole tunnel system, including the organisation of tunnel management, plays an important role in tunnel safety as it determines what the tunnel users see or have to respond to, in both normal and critical situations. The nature of the traffic regulations, motorists' compliance with them and the degree to which they are enforced contribute significantly to the level of tunnel safety. The properties of the vehicles using the tunnel and the loads they carry also play an important role.

Additional measures (with respect to the minimum requirements set by the EU-Directive) could be considered when focussing on human factors and human behaviour in terms of tunnel safety. Designing for optimal human use should include assessment of human abilities and limitations and ensuring that the resulting systems and processes that involve human interaction are designed to be consistent with the human abilities and limitations that have been identified. Human abilities and limitations refer to those physical, cognitive and psychological processes that deal with perception, information processing, motivation, decision-making and taking action.

The main conclusions regarding tunnel users are that:

• the design of tunnels and their operation should take account of human factors;
• drivers need to be more aware of how they should behave in tunnels;
• a fairly long stretch of road (if possible 150 - 200 m) before the tunnel portal should not contain too many signs and signals; the necessary signs and signals at the point of entry into the tunnel should be strictly limited in number;
• the tunnel safety facilities should be easily recognisable even in normal traffic;
• alarm signals should be provided by multiple-redundant sources (e.g. public address system and variable message signs)

Designing for optimal human use should include assessment of human abilities and limitations and ensuring that the resulting systems and processes that involve human interaction are designed to be consistent with the human abilities and limitations that have been identified. Human abilities and limitations refer to those physical, cognitive and psychological processes that deal with perception, information processing, motivation, decision-making and taking action.

Technical Report 2008R17 "Human factors and road tunnel safety regarding users"  deals with this topic. It discusses observations of the behaviour of tunnel users in both normal and critical situations and, in general terms, the main human factors that influence this behaviour. The report also formulates recommended measures, additional to the minimum measures required by the EU directive.

Technical report 2011R04 "Recommendations regarding road tunnel drivers' training and information" provides recommendations to all those in charge of education and information actions. The report develops proposals for educational elements for trainers, followed by practical instructions intended for the users. The document concludes with a number of suggestions and proposals that may be useful for the delivery of training and communication activities.

The main methodological recommendations to be implemented when it is desired to pay particular attention to human factors are:

1. the need to intervene as far upstream as possible in the framework of studies,
2. the crucial importance of taking account of the work carried out in the field of integration of human and organisational factors in safety,
3. the advantages of tests to validate innovative solutions liable to be implemented.

The first point particularly concerns the design of new tunnels for which it is fundamental to intervene as far upstream as possible during the studies. This allows better account to be taken of the main factors which govern the behaviour of users in road tunnels. Among these main factors, the following can be notably mentioned:

• data related to the local context, for example, the type of traffic and thus the users concerned (locals, professionals, subscribers, etc.),
• contextual items related to the existing infrastructures upstream and downstream from the planned tunnel (route continuity logic),
• other tunnels on the route or in the neighbourhood of the tunnel,
• cross-border tunnels for which particular attention must be given to the strategies and means implemented to communicate with the users.

The second point concerns making the best use of knowledge accumulated to date in the field of general road safety, and evacuation in crisis situations in particular. This can take shape in two ways: either by referring to general lessons learnt from work carried out in this field (PIARC recommendations for example), or by involving human science specialists (psychologists, experts) in the project. The lessons learnt from real events or from the numerous exercises held in tunnels show that the technical choices made by engineers specialised in the fields of equipment and safety in tunnels are not always the most appropriate from the viewpoint of user behaviour. Involving human science specialists should be considered for the most important projects (both new tunnels and refurbishments) with particular issues (cross-border and/or particularly long tunnels, tunnels of limited dimensions, complex tunnel structures, etc.)

Independent of the possible involvement of human science specialists, it is obviously necessary to take care to ensure a wide consultation of all the actors concerned at all times. In particular, the intervention services must be closely associated with the design of the safety equipment (particular attention must be given to features provided for self-help for evacuation of users).

The third recommendation concerns the tests and trials necessary to validate innovative choices when they are considered to be desirable. When it proves to be necessary to develop innovative means, the preliminary test phases must not be neglected (indoor testing for example), nor trials on site. These trials could be usefully performed with support from experts in the field of human sciences. Their objective will be to validate the innovative measures proposed before deployment in tunnels.

As a conclusion and in general, we emphasise the need to show much pragmatism and humility in this field. A basic principle consists in preferring simple and intuitive solutions whenever possible, in line with what is currently in practice in non-confined conditions. These types of approach ensure that the measures implemented are likely to be well understood and adopted by the users.