The Highway Development and Management Model (HDMM, current version HDM-4) has for many years been the primary tool, used by Governments and Development Banks, for the appraisal of major road networks of low- and middle-income countries.
With climate change and extreme events affecting the performance of roads, the onset of a big shift towards electric vehicles, and concern over vehicle emissions, now is the opportune moment to consider how we should update and develop the model further. This important update was discussed at a side event session of COP 26, hosted by Bernard Obika from the High Volume Transport Programme (HVT) and organised with the Climate Compatible Growth Programme (CCG).
The keynote speaker, Martin Humphreys, Lead Transport Economist, Global Lead for Transport Connectivity and Regional Integration, World Bank opened the session by firstly outlining the scale and importance of HDMM.
First established in 1971, currently 67 countries around the world hold the license for the software and it’s seen as commercially independent and cheaper than proprietary alternatives. He said:
“Almost since its inception, HDMM has been a pre-requisite to the provision of finance to client counties by a number of Multi-lateral Development Banks (MDBs), including the World Bank.
“Just to give you an indication of the scale and the importance of HDM-4, I can tell you that the World Bank currently has 162 active transport projects in its portfolio amounting to USS$31 billion, of which approximately US $20 billion are for connectivity (inter-urban and rural.) And in the pipeline is US$18 billion over the next three years.”
“Since its last update in 2005, and despite considerable research and need, the current HDM-4 has not been changed.”
He went on to explain that there are now a number of driving forces for change to HDMM. Primarily he explained that decision criteria in the current model do not include some key functional needs such as network resilience, estimation of greenhouse gas emissions and road safety.
In response to the need to update HDMM, a small group of stakeholders including the World Bank, FCDO, and Asian Development Bank (ADB) together with existing stakeholders from HDM-4 have looked to an initial business plan for the future of HDM-4 funded by HVT. The business plan explored the advantages and disadvantages of the current model and looked at the potential for the model going forward.
From this work, the World Bank has taken on the leadership for the project to update HDMM using a new global facility to decarbonise transport. To carry out the upgrade, an estimated US$3-5 million will be needed to cover technical improvements, platform changes, piloting, training and roll-out.
The World Bank, FCDO and World Road Association (PIARC) have committed funding into a new multi-donor trust fund and contributions in parallel and in-kind have been made by ADB, and the South Africa National Roads Agency (SANRAL).
Mr Humphreys concluded that great progress for the update has been made, and next steps will now include reaching out to more stakeholders to engage more funding.
Following the keynote, speakers explored further how HDM-4 can be used to incorporate climate issues into highway planning.
Dr Eric Stannard, CEO of HDMGlobal based at the University of Birmingham Enterprise, said:
“We know that climate change is having an impact on the performance of road networks, and it will continue to do so in the future. This is mainly due to the impact of higher temperatures, increased volume and increased intensity of rainfall that’s occurring and damaging the road and also the increase in extreme weather events that can result in flooding and landslides that have an impact on road networks.
“So, when using the HDM-4 tool we need to take these factors into account. But the HDM-4 models were developed before climate change was recognised as a major issue and there are limitations with the climate model in HDM-4 robustly predicting the effect of the changing parameters on the network. For example, the climate parameters defined use average values and therefore do not capture the extreme weather events such as intensity of rainfall, and prolonged heatwaves.”
Speaking of where improvements will be made in the new HDMM, Dr Stannard outlined three key areas:
- Climate Change Models – the climate model and analytical framework should be updated to allow analysis of the resilience of the road network to climatic changes, this includes:
- Road deterioration models
- Resilient Maintenance standards
- New pavement materials are being introduced which are more resilient to the impact of climate change. New deterioration models are therefore required to bring these into HDMM.
- Decarbonisation of Transport – Estimation of greenhouse gases resulting from the full lifecycle of road construction and maintenance, vehicle manufacture and use, and fuel production.
Michael Anyala, PhD, Senior Road Asset Management Specialist, Asian Development Bank spoke about the ADB HDM-4 Road Decarbonisation toolkit.
He outlined the many sources of emissions involved in the development, maintenance and running of roads from the production of the raw materials, to building the road, to the vehicles that will use the road in its lifetime. To address how to decarbonise these areas, ADB has developed a decarbonisation toolkit using HDM-4.
The toolkit is at a pilot stage and should be completed by the end of the year, and plans are in place to launch the toolkit in Spring 2022.
John Hine, Transport Economist, spoke about outstanding issue in HDM-4 saying: “HDMM presents a good opportunity for us to re-evaluate what we want from a road planning model. Things like carbon pricing needs to be brought into construction, road maintenance and vehicle operating costs, for example.
“A radical overhaul is needed of vehicle operating costs relationships (VOC) relating to internal combustion engine vehicle (ICT). ICT vehicle technologies have changed in the last 30 years and there is evidence of cost overprediction. The introduction of new vehicles will also have a profound effect on modelling the VOC benefits.”
Tyrone Toole, from the Australian Road Research Board, evaluated the life cycle impacts of climate and extreme events using an HDM-4 based framework.
In one example, looking at cyclones in Australia 2010 to 2013 and the increased extreme events, he outlined how we’ve learnt that there was a large proportion of pavement failure; that table drains were blocked or inadequate, and that there were many sections ‘waiting’ to fail. He explains that there are many factors that we need to become better at analysing and building into road planning in the future.
The session was an important opportunity to better appreciate how climate issues must be considered when planning road maintenance and future development. The updating of HDMM will be a critical tool in bridging this current gap.
Watch the full presentation below.