2025/09/03 by Ahmad, Abdullah, Tazim Ameen
Engineering · #Civil and Environmental Engineering #Disordered traffic #Driver behavior #Engineering #Heterogeneous traffic #PCU #Roundabout geometry #Roundabouts
paper · doi:10.17605/osf.io/4mghp
The dataset originates from an experimental study designed to estimate Passenger Car Unit (PCU) values at 13 urban roundabouts located in India. The experiments focused on capturing the combined effect of geometric design parameters (such as central island diameter, circulating width, entry and exit widths) and traffic composition (2W, 3W, standard cars, big cars, and heavy vehicles) under heterogeneous and disorderly traffic conditions. Traffic movements were recorded and analyzed to extract vehicle-specific parameters, including orientation time (O.T), effective widths, and trajectory angles (sin θ). A behavioral coefficient (α) was introduced to account for variability in driver aggressiveness, enabling classification into rash, moderate, and pacific driving styles. Using these parameters, PCU values were computed systematically for each vehicle category relative to the baseline standard car (SC = 1). The resulting data provides both site-specific PCU estimates and a consolidated view across all roundabouts. This structured dataset facilitates reproducible research into traffic flow modeling, driver behavior analysis, and capacity assessment at roundabouts. The data elaborates the development of novel PCU estimation under heterogeneous, disordered traffic conditions. This workbook contains PCU (Passenger Car Unit) calculations for 13 roundabouts (R1–R13), plus two reference sheets. Each roundabout sheet stores (i) site geometry (central diameter, circulating, entry/exit, approach/departure widths), (ii) vehicle-class characteristics (2W, 3W, SC, BC, HV; length/width), and (iii) the inputs and outputs of a new PCU formulation evaluated across a behavior parameter α. Intermediate variables include O.Tᵢ, O.Tcs, Wᵢ, Wcs, sin θᵢ, sin θcs, and |ln(sin θᵢ/sin θcs)|, with PCU reported per vehicle class for multiple α values. Across all roundabouts the file contains ~9,500 PCU records (five classes), with α ranging ~0.13–4.34. Observed PCU value ranges (over all sites) are: 2W ≈ 0.14–0.54, 3W ≈ 0.52–1.22, SC = 1.00 (baseline), BC ≈ 0.80–2.19, and HV ≈ 2.00–5.04. The Sheet1 tab compiles sin θ values by roundabout and vehicle class, while Sheet2 provides a template table that groups α settings by Rash / Moderate / Pacific behavior and shows worked examples of the PCU computation pipeline (O.T, widths, sin θ, and resulting PCU). Reuse potential. The dataset supports (a) calibration/validation of PCU models for heterogeneous, disorderly traffic, (b) sensitivity analysis of PCU versus α (driver behavior), (c) cross-site comparisons linking geometry and traffic composition to PCU, and (d) downstream indices such as a Roundabout Heterogeneity Index (RHI) or simulation/capacity studies. Data values and structure. Data are organized per site in wide tables (up to ~64 columns) with clearly labeled header rows for the computation blocks; some empty “Unnamed” columns are placeholders from the original formatting and can be dropped without loss. Legal/ethical considerations. The workbook contains no personal or identifying information; values are derived counts/measurements and formula outputs from public-space traffic studies. Ethical risks are minimal; users should cite the source, respect any local data-collection permissions, and, if sharing, apply a clear open-data license (e.g., CC BY 4.0) as appropriate.