Introduction. Effective management of surface runoff from urbanized areas is a key task in modern construction, directly impacting the safety, functionality, and longevity of structures. Traditional solutions and calculations that permit the flooding of a catchment area up to the height of a curbstone are unacceptable for use on bridges. Incorrect calculation of drainage parameters can lead to aquaplaning, saturation of structural elements, and their subsequent destruction, which necessitates the improvement of existing methodologies. The primary method used in Ukraine for calculating stormwater runoff from a catchment basin is the limiting intensities method, described in [4]. Globally, Manning’s formula [1-3, 11] is widely used and applied.
A separate, yet critically important, and often-ignored aspect is the relationship between theoretically justified minimum slopes and the accuracy of their practical implementation. When designing and constructing bridge structures, the determination and provision of minimum longitudinal slopes required for effective drainage depend directly on the accuracy of measuring equipment (levels, total stations) and the qualifications of the workers. Small slopes can turn out to be less than the permissible measurement error, making their practical realization impossible and leading to the formation of stagnant zones. Thus, the analysis of the influence of slopes must be integrated with an assessment of the practical feasibility of the specified parameters.
Additionally, the probability of errors in theoretical calculations must be considered, and a significant challenge is the correct practical implementation of design solutions. In this context, the construction camber, which is a pre-calculated imitation of reverse curvature, is a mandatory design element for span structures to compensate for their deflection under permanent and temporary loads. Inaccuracies in the determination or implementation of these elevations directly affect the actual longitudinal and transverse slopes on the road surface. Even minor deviations in the construction camber elevations can nullify the design slopes needed for effective drainage, leading to the formation of local areas of water stagnation and impaired drainage functionality.
This study simulates the formation of surface runoff using Manning’s formula [1-3, 11] and the limiting intensities method [4]. During the simulation of surface runoff movement, the main task was to determine the maximum depth of the surface runoff layer, followed by identifying the key factors influencing its magnitude. The simulation of surface runoff formation was performed considering variable longitudinal and transverse pavement slopes, the geometric parameters of the catchment area, the distance between water intake elements, and their width.
Problem Statement. One of the prerequisites for the effective functioning of a bridge’s drainage system and the protection of its structures is the rate at which surface runoff is received by water intake elements. The primary indicator that determines the speed of runoff movement is the surface slope. Errors and inaccuracies can lead to a decrease in slope and a reduction in the effectiveness of the drainage system.
Objective. To simulate the process of surface runoff formation using the Manning and limiting intensities methods. To determine the volume of runoff that forms from a local catchment area in front of a drainage element. To determine the minimum permissible longitudinal slopes for bridges, taking into account the need to ensure the functionality of the drainage system.
Materials and Methods. This study employs a comprehensive approach based on the analysis of scientific and technical developments in the field of surface drainage and stormwater sewerage design, as well as practical experience in their installation. The methodological basis of the work is an analysis of current building codes and a comparison with relevant foreign regulatory documents and technical literature. To ensure the comprehensiveness of the study, domestic and international experience gained during the design, installation, and operation of drainage systems has been taken into account. Mathematical modeling methods were used to determine the optimal key factors that govern the magnitude of surface runoff formation and the minimum permissible longitudinal slopes of the bridge deck that ensure the effective functioning of the drainage system.
Results. The key factors influencing the formation of surface runoff have been identified. The magnitude of the longitudinal slope that ensures the effectiveness of the drainage system has been substantiated.
Conclusions. The research demonstrates that to ensure effective drainage and prevent the destruction of bridge structures, it is necessary to consider not only theoretical calculations but also the practical implementation of design solutions. Achieving a minimum permissible longitudinal slope of no less than 0.2 % is a key condition for ensuring the reliable functioning of the drainage system.
