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Description
The FORS4Wheels is a Croatian Science Foundation project that is focused on the experimental and quantitative analysis of the accessibility of forest and urban green trails for wheelchair users, to determine the relationship between the morphological characteristics of trails and the biomechanical as well as subjective load experienced by users. The study integrates geodetic, engineering, biomechanical, and ergonomic methods to ensure an objective and multi-level assessment of accessibility.
Longitudinal trail profiles were measured using a high-precision GNSS RTK system connected to the national reference positioning system to achieve centimeter-level accuracy in both horizontal and vertical components. In areas with reduced satellite signal availability, a total station was used to ensure data consistency and reliability. Based on the collected coordinates, detailed longitudinal profiles were generated, and the trails were segmented according to slope categories and the length of slope sections within a GIS environment.
Surface roughness was quantified using a high-precision laser scanner to capture the longitudinal microprofile of trail surfaces. The acquired data were processed using specialized software, and roughness was expressed through the International Roughness Index (IRI) as a standardized indicator of longitudinal unevenness. This approach enabled objective comparison of different surface materials and the quantification of micro-irregularities relevant to wheelchair mobility.
Vibration exposure during movement was measured by mounting tri-axial accelerometers on the wheelchair frame. The sensors recorded accelerations in the vertical, longitudinal, and lateral directions, and analyses included maximum amplitudes, root mean square (RMS) values, and the frequency spectrum of vibrations. The data were processed in numerical analytical environments, and the results were correlated with measured slope values and IRI indices to determine the relationship between geometric and surface parameters of trails and the vibration load experienced by users.
Physiological load was assessed through continuous heart rate monitoring while participants traversed defined trail segments. The relative increase in heart rate was used as an indicator of physical exertion intensity. At the same time, subjective workload was evaluated using an adapted questionnaire based on the NASA-TLX methodology, assessing physical demand, perceived safety, level of frustration, and perceived control of movement.
By integrating spatial, surface, vibration, physiological, and perceptual data, a multidisciplinary analytical framework was developed for assessing forest trail inclusivity. The results will enable the identification of critical slope and roughness thresholds associated with increased vibration exposure and subjective feelings of insecurity. This methodology provides a scientifically grounded basis for defining technical guidelines and threshold parameters in the planning and adaptation of forest trails, with the goal of ensuring safe and independent mobility for wheelchair users.
| Keywords | Accessibility; Roughness(IRI); Vibration; Wheelchair |
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