High Volume Transport

Vital transport research to ensure accessible, affordable and climate friendly transport for all.

Supporting the next generation of the Highways Design and Maintenance Standards Model

HVT is pleased to conclude a number of preparatory reports supporting the updating of the Highways Design and Maintenance Standards Model (HDM.) Several HVT financed-studies were part of the World Bank-led multi-stakeholder global initiative to restore the integrity and accuracy of HDM. The tool has for many years been the primary method used by Governments and Development Banks for the appraisal of major road networks in low- and middle-income countries (LMICs) but has not had a revised edition since 2005.

To support the longevity of the update, HVT conducted research in 2022 that identified and captured the user and business requirements for the next version. This included understanding the use of HDM-4 by road administrations, development banks, international development agencies, consultants, academics and other stakeholders.

In 2024, the World Bank identified six complementary initiatives that were designed to lay the foundation for the development, launch and management of new software and model, HrDM-5. HVT led on three of these projects:

The project delivered by TRL includes a series of technical papers which define the vision, mission and goals for HrDM-5. It addresses high-level scoping issues, including the classes of road to which HrDM-5 should apply and the role of Information Quality Levels, within a new analytical framework. Key gaps addressed include models for road deterioration, crash prediction models for incorporation of road safety analysis and support for greenhouse gas emissions modelling.

Two further projects that HVT funded focused on updates that were needed to model Road User and Environmental Effects (RUE). The HDM-4 v 3.0 edition of Modelling Road User and Environmental Effects is a comprehensive guide detailing the road user and environmental impacts within the HDM model. It is part of a suite of HDM-4 documentation. HVT also funded the gap analysis on RUE to better inform the development of HrDM5.

The two projects provided a comprehensive review of the existing literature on emissions, mechanistic fuel and tyre consumption modelling and updated models for use in HrDM-5. Through collaboration between projects, several papers were delivered that contributed to the first draft of a new HrDM-5.0 RUE book, version 0.1.

Kevin McPherson from TRL explained how the new HrDM-5 will support the transport sector. He said: “By equipping planners and decision-makers with advanced tools and methods, HrDM-5 will help drive improved sustainability, resilience and safety of key road infrastructure for the next 20 years and beyond.”

Once HDM-5 becomes available for use, it will be widely used for economic analysis of road development and maintenance in LMICs, with high uptake expected from LMICs, MDBs, and transport professionals and consultants. HDM is currently used to appraise about $20 billion of road investments each year (FCDO 2023). By restoring modelling integrity and accuracy, and incorporating estimation of the effects of climate change, traffic accidents, and other factors, HDM-5 will significantly improve the completeness, quality, accuracy and reliability of economic appraisal.