The effort by the French government to improve guardrails started with the report “Les glissières métalliques dans l’accidentologie des motocyclistes” published by SETRA (Service d’Etudes technique des Routes et Autoroutes) in 1997. It studied guardrails-related accidents between 1993 and 1995 in France, in order to assess the effectiveness of existing measures in place since 1986 (constant curve radius, increased visibility in curves, quality of the road surface, etc.) and the need for further actions.
Data shows that over the time period, 188 motorcyclists were killed impacting single beam metal rails, representing 5% of all fatal injuries caused by impacting obstacles. In comparison, only 18 deaths (1,7%) are attributable to concrete barriers, and 10 deaths (1%) to other barrier types. When all injuries are taken into account (light, serious and fatal) the trend is reversed: single beam metal rails represent only 10,5% of injuries, and concrete barriers 2,5%. Metal rails without an MPS are therefore associated with higher fatality rates and a lower chance of survival. Obstacles represent just under 50% of all motorcyclist deaths, but only 17% of motorcycle accidents; however, underreporting is an issue due to the lack of witnesses in single vehicle accidents, which are the most common configuration in crashes against obstacles.
Fatal accidents against all road restraint system types total 8.9% of fatalities. Single beam metal rails are by far the most dangerous obstacle for motorcyclists, killing 63 on average every year – 7.8% of all fatalities.
The trend is even stronger in non-urban areas, where accidents with obstacles represent one third of all motorcycle accidents, and 40% of fatalities. The share of fatalities attributable to road restraint systems soars to 13.3% of the total, and for single beam metal rails alone, 12.1%.
In urban areas, where guardrails are less prevalent and other obstacles such as sidewalks, posts and parked vehicles are the most common obstacles impacted, single beam rails are still responsible for 13 deaths per year, 7.1% of all deaths attributed to obstacles, and 3.2% of all casualties.
Where are guardrail-related accidents the most common? They happen in majority in non-urban areas (79.3% of cases), and more often on single carriageways (47.4% of cases) than on dual carriageways (31.9%).
The road geometry is an important parameter: more than 60% of guardrail-related fatalities are located in curves. Inclination is also a factor, especially in non-urban single carriageways.
The general profile of guardrail-related accidents points at non-urban single carriageways, in tight curves: 30% in curves with a radius over 400m, 17% in curves with a radius between 250 and 400m, and 53% in curves with a radius under 250m.
On dual carriageways, where the curve radius is most often over 400m, more research is needed to identify typical black spots and, if any, the curve radius associated with this type of accident.
The author concludes that while they represent only 2% of all road deaths, guardrail-related accidents are abnormally dangerous because they disproportionately affect motorcyclists. She writes that “Guardrails aim at improving the safety of all road users. The fact that they have a negative effect in certain circumstances makes the situation unacceptable” and notes that while the analysis confirms the importance of curve scenarios, it shows clearly that corrective measures solely aimed at this scenario would not alone solve the metal guardrail problem for motorcyclists.
The 1999 Directive on Motorcyclists Protection Systems
As a result of the 1997 SETRA report, a 1999 government directive (Circulaire n° 99-68, October 1st, 1999) was published to cover the installation of MPS, including their location and type. It mandates the use of MPS in curves where the radius is under 400m on highways, and 250m on other roads. It acknowledges the results of the SETRA study, underlining that guardrail-related motorcyclist accidents are “abnormally severe” with a severity 5 times higher than average, and their consequences “often spectacular and tragic”.
The directive insists on the need to reduce the risk of accident in the first place, by focusing on visibility of the road, intersections and curves; on maintaining constant radius in curves, on avoiding sideways road inclination, and on the quality of the road surface (grip, evenness, water flow, cleanliness). All these efforts also contribute to the safety of other road users.
If the use of guardrails is necessary, the use of approved MPS is compulsory in the curve exterior:
- on dual carriageways, in curves with a radius under 400m,
- on all other roads, in curves with a radius under 250m,
- at inclined intersections, on all road types and all curve radii.
During the drafting stage of the directive, a nationwide contest was launched by the Inter-ministerial Road Safety Committee (CISR) calling for innovative and competitive MPS designs. The call for tender offered two possibilities: a new design, or an add-on design for existing systems.
The LIER protocol for MPS testing was created as part of the call for tender in order to select the best available design. Two systems were approved as a result, one new design (MOTO-RAIL by SOLOSAR) and one add-on for existing rails (ECRAN MOTO-TUB by SODIREL). A pre-existing add-on, steel-screen design by SEC-ENVEL was also approved using the protocol.
Assessment and further research in 2011
A decade later, the CETE (Centre d’Etude Technique de l’Equipement, branch of the Ministry of Transport) is conducting since January 2011 research to answer the following questions: are MPS effective? If yes, on which type of roads, and curves? Where are the points of impact with the motorcyclist? In addition, the conformity of the MPS, its installation and maintenance are also checked whenever possible in order to obtain data on the ageing of the systems.
Based on accident reports established by law enforcement, the team hopes to come up with reliable results, despite the lack of detailed information on many single vehicle accidents, due to the lack of witnesses.
Preliminary results indicate that a significant number of accidents against guardrails occurred on straight road sections, prompting researchers to consider the replacement of all guardrails with MPS, the cost of which is estimated at €1 billion.
Final results are expected to be published in 2012.
 Karine Pothin, under the direction of Guy Desire, CETE de l’Ouest