In the Austrian lands of Carinthia and Lower Austria, extensive viewing analyses with motorcycle drivers were executed at accident sites and risk areas on selected routes. The viewing analyses revealed incorrect viewing strategies and faulty priority order as main causes for accidents. Many accidents are caused by wrong viewing behaviour, missing viewing points, misjudgements and complexities (uncoordinated viewing strategies caused by excessive information) that are too high especially at high velocities. Using the TÜV-certified viewpointsystem® viewing analyses, the objective evaluation of real viewing behaviour, the danger recognition and reaction behaviour of motorcyclists were investigated for the first time. Viewing analyses allow the complete observation of detail recognition and the perception of surroundings. It became apparent that the choice of driving line is significantly influenced by the viewing behaviour. Especially in bends, incorrect posture of the head results in perspective distortions and misjudgements. Especially at high driving speed the angular velocities, and thus the error magnitude, increase. Over the course of the analyses, the 3 following results can be derived for the accident and danger sites: 1. Illustration of incorrect priority orders (accident-causal reversal of order in the perception) This means that there are constant causal relationships from distinctive visual features or movements (see also extensive viewing studies and works on viewing research by the author). Bright areas, movements, conspicuous objects are always perceived earlier than inconspicuous ones. This explains the masking of safety-relevant objects. 2. Analysis of navigation gaps (navigation lapses) in dangerous bends Another important result of the study is the finding of so-called navigation lapses on the taken routes, i.e. points at which too few points of guidance are given and a ‘loss of orientation’ becomes evident. Ordered viewing strategies are not possible at these points, and incorrect reactions of the motorcyclists are a given. 3. Finding of perspective misguidance The analyses of the perspective visualisations at accident hot-spots show potential areas for misjudgements and allow specification of unsafe navigations of curves. Locations with real perspective misguidance are usually present when misjudgements caused by a wrong head posture are given from the road layout — mostly in double curves. For less experienced drivers, the visual horizontal plane often shows an angle of 16°, in some cases even greater, so that angular changes can no longer be associated within each time/distance segment and physiological real errors in estimations must occur. All these interrelations, as presented by the author, explain the singularity of traffic accidents with motorcycles, which was recognised in the viewing analyses, and require completely new approaches by the traffic authorities. Classification of errors based on detailed viewing analyses: A. Analysis in dangerous situations - The following (negative) abnormalities are present: * Inexact choice of driving line and cutting of curves — sudden corrections of the driving line become necessary during navigation of the curve. Increased danger of overreaction (sudden braking etc.) when the driver is startled. Errors in navigation behaviour caused by: - Information defects - Perspective misjudgements - Static / dynamic viewing obstructions - Distractions e.g. by road signs in unfavourable positions just before entry into the bend and overly long viewing fixations to these elements. - Inadequate equipment of guidance elements leads to increased number of searching processes. * Unclear interactions with other road users. * Incorrect danger recognition — neglecting safety relevant control gazes. * Reversal of priorities in the viewing strategies of drivers. Relevant information is masked by less important, but more conspicuous stimuli. (compare: distractions from forced viewing attraction by peripherally appearing stimuli) B. Analyses at accident sites - The viewing-related and safety-related detail analyses of accident sites (singular accidents as well as accumulations) show that often the following environmental conditions were present: * Missing or incomplete equipment with vertical guidance elements complicates the optical guidance considerably. * Frequent changes between light and shade necessitate constant adaptation, during which no ordered perception occurs. * Reversal of priority order especially in complex traffic situations (parked vehicles or entrances to touristic destinations on overland roads). * Partially faulty optical guidance or expansions of the road surface, such as wide, undefined road surfaces or widening of the road in curves etc. * Narrowing curves (three-center curves, clothoids, et al.). * Wrong or unfavourable cross slope (“hanging curves“). * Inhomogeneous friction of the surface layer from maintenance work. * Unfavourable road markings: lack of announcements of solid line / border line in dangerous segments. * The accident circumstance “sudden braking“ often noted in accident protocols, gives a potential clue to overreactions of drivers in hot spots. C. Analysis in perspective interactions - Using detailed perspective analyses on selected examples, the following interrelations could be verified: * Gaps in information transfer: These gaps explain unstructured navigation behaviour because of missing navigation points. This causes search processes and distractions from relevant navigation processes. The result is a negative influence on the choice of driving line or delayed recognition of bends. * Distortion / wrong perspective appearance: Unfavourable head posture leads to angular deviations of the eye axis from the horizontal of up to 16° or more. This complicates the estimation of curves and leads to information defects (misestimations). Result: Safety analyses must increasingly take into account perspective interrelations. Systematic Interactions between Human / Street / Technics: The results of the detailed accident studies and viewing studies of motorcyclists show that in the system human-street-technics, human information perception has a defining influence on the traffic safety. The factors are in direct relation to each others, the controlled information perception is continuously required: 1. Human factors a. Order of priorities b. Perception / navigation of curves c. Perspective interrelations depending on the head posture d. Danger recognition and danger estimation e. Driver experience: “Beginner” vs. “Seasoned driver“ etc. 2. Street a. Surface conditions b. Road markings c. Road equipment — guidance elements d. Road environment design e. Environment conditions (vertical curves, three center curves, clothoids, et al.) etc. 3. Technics a. Driving technique: Body and head posture in curves etc. b. Time-distance sequences c. Driving velocities etc. Result: The human information perception (human factor) is in constant direct relation to the vehicle and the road. Accident analyses therefore need to consider not only singular factors, but all dependencies between all factors. (Author/publisher)
Abstract