Since 2001 articulated vehicles commonly referred to as LHVs (Longer and Heavier Vehicles) have been permitted on public roads in the Netherlands. Because there had been no prior experience to build on, a pilot scheme was introduced first. LHV authorisations were subsequently extended gradually. An evaluation phase for LHVs has been in effect since 1 November 2007. This means that this is the first time that LHVs are being driven around on such a large scale.
On 1 July 2010, 153 companies had been given a dispensation and 397 towing vehicles had been issued an exemption to drive with an LHV combination. Both the number of LHVs and the number of routes covered by LHVs are expected to steadily increase over the coming period. The Dutch Minister of Infrastructure and the Environment wants to keep tabs on this, particularly in relation to road traffic safety. Although previous research has given no cause for concern over the traffic safety of these types of vehicles, it is important to eliminate any possible risks accompanying the increase in the number of LHVs. The first monitoring study was conducted in 2009. And another monitoring study was conducted in 2010.
The research aims to provide insight in whether the current deployment of LHVs is causing issues in relation to road traffic safety, traffic flows and road design. The study consists of an analysis of LHVs, interviews with experts and an analysis of core areas.
This study answers the following research questions:
1 Did an analysis of the accidents involving LHVs bring to light any possible issues following the authorisation of LHVs on the Dutch road network? If so, what are these issues?
a. How do these differ from accidents involving regular trucks?
b. Is there a difference between driving on the motorway and the underlying road network?
2 Can differences between the different LHV configurations be observed?
a. Which other aspects particularly attract attention in analysis of the accidents that occurred whereby LHVs were involved?
b. What are the general observations of the experts experienced with LHVs in core areas, specifically in terms of road safety in relation to vulnerable road users, traffic flows and road design?
c. How do these experiences differ from regular road traffic?
d. Can differences be observed between the different core areas or forms of local road management that offer points of application for policy?
Outlines for research
On the basis of a few research questions it was investigated whether the current deployment of LHVs on the Dutch road network causes any issues in terms of road traffic safety, traffic flows and road design. Police accident reports and accident statements from transport companies and insurers served as a basis for answering the research questions. Analyses of recorded accidents involving LHVs alone, however, provide insufficient basis to substantiate reliable conclusions in relation to the traffic safety of LHVs nationwide; since the number of LHVs involved in accidents is too limited to allow statistical analysis. Therefore, accident reports have been used to design a number of case studies, which, in turn, were examined on the basis of accident statements submitted by companies and insurers, and the case studies were subsequently tested against the experiences of LHV drivers, some of whom having had one or more accidents with an LHV and others having had no such accidents. Finally, in order to create an exhaustive image of possible risks attached to the use of LHVs, the case studies were tested against the judgement of other important experts by experience, such as road managers, examiners and enforcement bodies.
Simulated case study analysis
The driver and examiner interviews alone, however, are insufficient. In order to gain a complete overview of any possible risks involved with deployment of LHVs, additional sources are required. It was therefore decided to apply simulated case study analysis. In this methodology, derived from criminal investigation, it is attempted through analysis of available facts – by way of statements from witnesses and witness experts – to ‘fill in the blanks’. Based on the bare facts, hypotheses are formulated, which are then tested against experts’ insights and, if necessary, refined and amended. This significantly increases the reliability and usability of the results, even if there have only been few cases available for analysis.
The recorded accidents involving LHVs served as a basis for this study. These were subsequently further elaborated with the experiences of LHV drivers who had been in one or more accidents with an LHV and LHV drivers who had not had any accidents. Their judgements were then tested against the expert opinions of people such as those working in road management and road maintenance, and employees of companies that use LHVs. The deliberate starting point of the analysis was that an increase in the number of LHVs is accompanied by risks in terms of road traffic safety and issues in relation to traffic flow and road design. Rather than prove that an increase in the number of LHVs will not bring about any additional risks, the aim has been to disprove that an increase in the number of LHVs will bring about additional risks. Firstly, this approach ensured that as many issues and risks as possible were systematically investigated and examined. Secondly, it enabled the researchers to pass firmer judgements in respect of the probability of any issues to occur.