PyBTLS - Python Bridge Traffic Load Simulation

PyBTLS is a Python wrapper of the C++ based terminal program BTLS (bridge traffic load simulation). It provides four main functionalities:

• Generating new traffic;
• Reading historical traffic;
• Calculating load effect;
• Processing the load effect data.

PyBTLS has the following advantages:

• Highly configurable traffic generation - The adjustable traffic statuses include flow type, traffic volume, composition, average speed, etc.;
• Flexible traffic load calculation - Influence lines/surfaces are used;
• Efficient simulation running - C++ backend and Python multiprocessing support;
• Embedded load data processing - Block maximum, peak-over-threshold, rainflow;
• Well-organized output - Result data are saved in structured folders and can be read as pandas DataFrame.

However, please note that PyBTLS is not doing traffic microsimulation; Instead, it only applies a simplified vehicle-chase model to avoid vehicle overlapping on the bridge. Therefore, it should either be used for simulating traffic on short-to-medium length bridges, where the driver behaviours like lane-changing can be considered negligible due to the short crossing time; or for getting input traffic for more detailed microsimulation software.

Installation

To install PyBTLS, please ensure that you have Python 3.10 or higher installed and are on a 64-bit system. Then, just do:

pip install pybtls

If you want to build from the source or build as BTLS, see the Installation Guide.

After installation

The following resources are available to help you get familiar with PyBTLS:

• The Minimal Working Example is a quick introduction to running a simple traffic simulation using PyBTLS.
• The Documentation provides all the information needed to build PyBTLS and conduct different simulations supported by PyBTLS. More examples can be found in its tutorials section.
• The Manual is for the C++ terminal program BTLS, which includes more detailed information about the simulation mechanism.

Credits & Copyright

Until 2025, PyBTLS is based on BTLS by Colin Caprani; Modified by Ziyi Zhou; Also contributed by Akbar Rizqiansyah.

• Copyright (c) 2001-2022 Colin Caprani;
• Copyright (c) 2022-2024 Colin Caprani, Ziyi Zhou, Akbar Rizqiansyah;
• Copyright (c) 2025-* The PyBTLS developers (see contributors on GitHub).

Main Reference

O'Brien, E., Nowak, A., & Caprani, C. (Eds.). (2021). Bridge traffic loading: From research to practice. CRC Press.