Client Overview: Cestel

Smart Mobility
Intelligent Transportation Systems (ITS)
Public Infrastructure Monitoring
Cestel

Cestel is the developer and maintainer of SiWIM® (Site Weigh-In-Motion), a cutting-edge system that captures vehicle weight, classification, and dynamic movement over bridge structures. Used globally, SiWIM provides essential data to transportation authorities for vehicle monitoring, infrastructure planning, and overload enforcement. The system is capable of measuring axle weights, vehicle speed, classification, and license plates using a combination of strain gauges and IP cameras, connected through a local network.

Website: https://cestel.si/en/siwim/

The Challenge

Legacy Architecture & Scalability Limits

SiWIM’s architecture relied on a combination of Python scripts, rsync for data synchronization, XML logs, and a monolithic PHP-based web frontend for monitoring and administration. This setup proved inflexible for modular upgrades, and lacked modern UI capabilities, scalability, and hierarchical access control needed by international stakeholders.

The existing system also faced the following constraints:

  • Limited UI usability across platforms (mobile/tablet compatibility).
  • Manual VPN key management for users and systems.
  • Static PNG-based visualization.
  • Inadequate flexibility for custom configurations, filters, or module expansion.

The Goal

To rebuild the SiWIM monitoring server from scratch with a modular, scalable, and secure architecture using modern open-source technologies. The upgrade aimed to enhance user experience, enable multi-tenant access, support internationalization, and ensure secure VPN management via a web interface.

Our Approach

We analyzed the full lifecycle of SiWIM data—from field capture to centralized monitoring—to identify upgrade opportunities without interrupting current system operations. Our implementation emphasized modularity, portability, and extensibility.

Key Features Developed

  • Modular Web Architecture: Clear separation of SiWIM-S, SiWIM-M, and SiWIM-P modules, accessible via a unified login portal.
  • Dynamic Graphs: Replaced static PNGs with interactive JavaScript visualizations for vehicle data, system voltage, and temperature.
  • Hierarchical Access Control: Group-based permission model with multi-level geographic segmentation (e.g., per country, agency).
  • VPN Key Management: Admin interface for generating and assigning VPN credentials to users and systems.
  • Internationalization & Units: Support for multiple languages and both metric and imperial units.
  • Real-Time Monitoring: Retained vehmon/vehpic functionality with improved UI for alerting and filtering.
  • Mobile Optimization: Fully responsive UI for desktop, tablet, and mobile use.
  • Extensibility: Future support for new modules (e.g., ANPR, weather stations, structural monitoring) via plug-and-play architecture.

Tech Stack

Frontend

  • Angular: Used to rebuild the SiWIM-S (system monitoring) and SiWIM-M (live monitoring) interfaces for responsive, dynamic, and mobile-friendly dashboards.

Backend

  • Node.js: Used for developing the backend services, including user authentication, VPN key generation, alarm routing, and data ingestion.
  • Python: Existing Python-based services (e.g., vehmon.py, vehpic.py) were retained and interfaced with the new architecture.

Infrastructure

  • Debian Linux: Used as the baseline OS.
  • Nginx: Lightweight web server for secure HTTPS communication.
  • OpenVPN: Integrated for secure remote access, now managed via web UI.
  • Certbot: Automated SSL certificate renewal.

Outcome

The modernized SiWIM platform significantly improved user engagement, operational efficiency, and system transparency. Users now benefit from a rich, filterable data interface, seamless alarm integration, and easy system management. Administrators can configure system behavior, user permissions, and access rights from a single control panel. With Angular and Node.js forming the foundation, the platform is now positioned for long-term growth and adaptability.

Next Steps

With the new architecture in place, Cestel is now exploring enhanced predictive analytics using machine learning, integration with national enforcement systems, and real-time overload detection with ANPR and geofencing.

Our expertise helps companies optimize processes, boost efficiency, and unlock the value of their data to drive long-term growth.

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