Estimation of Operating Speeds at Road Humps on Short Street Sections with a 30 km/h Speed Limit

The application of traffic-calming measures (TCMs) constitutes an important preventive approach that improves road safety, particularly for vulnerable road users in urban environments. Due to economic considerations, the most commonly implemented measures are road humps (including speed humps, speed tables, and speed cushions), which significantly influence driver behaviour and contribute to speed reduction. Previous studies have demonstrated their considerable effectiveness; however, they remain limited and do not fully address certain important aspects, such as the relationship between speed reduction and the distance from a road hump, or operating speed as a function of road hump type while accounting for the influence of other contextual variables. This study considers three types of road humps installed on streets with a speed limit of 30 km/h in the city of Szczecin, Poland. To complement existing research, vehicle speeds were recorded using multiple speed measurement devices deployed along the analysed street sections. The placement of these devices on short street sections accounted for the influence of the following factors: street type, the presence of protective bollards, different parking conditions and arrangements near the analysed road humps, and their location relative to junctions. To ensure consistency and comparability of the analyses, each type of road hump was examined on the same street. Standard statistical analyses were performed for all speed datasets, with speed treated as the dependent variable and the aforementioned factors as independent variables. These analyses enabled the estimation of operating speed and the zone of influence for the three types of road humps, considering various determinants. The results indicate that vehicle speed is strongly dependent on the distance from a given road hump, its location within a street section between junctions, and the parking conditions in its vicinity. The outcome of this research is the development of a comparative framework for different types of road humps, with their corresponding operating speeds and zones of influence under specific contextual data. It may serve as a basis for design decision-making when planning road humps on short sections of residential streets (up to 250 m between junctions) located in suburban areas. The framework should be further supplemented and updated by other researchers as new empirical evidence and research experience become available.