Global Framework to Measure Climate Hazards’ Impact on Road Networks

Robust and resilient transportation networks are the backbone of an advanced society. These road networks allow the transportation of people, goods, and services that a thriving economy and human well-being rely upon.

However, road systems are vulnerable to different forms of disruptions. And many countries, particularly low-income countries and Small Island Developing States (SIDS), still need more reliable and resilient infrastructure systems.

A study published on 11 May 2023 in Environmental Research: Infrastructure and Sustainability aims to understand how road networks are affected by various disruptions, locate the hotspots of network vulnerabilities, and help prioritise and target future investments to increase road network resilience. Researchers analysed the country-level network vulnerabilities using the available geospatial information of roads through OpenStreetMap (OSM).

Researchers looked at how a country’s road characteristic impacts the resilience of its road networks. These characteristics include economic such as income level or degree of urbanisation, the terrain or geographic characteristics and whether or not the country is landlocked.

They have exposed 208 national road networks from various countries to different disruptions schemes – random, local, and targeted disruptions, and see how these road systems respond to various natural hazards.

These disruption schemes used in the study mimic natural hazards like flash floods – treated as a local or targeted attacks, and winter storms are described as random attacks.

“Random attacks are applied through systematically removing random combinations of links from connected road networks. Local attacks are applied by removing all edges within a specific grid cell, and targeted attacks are applied by removing single road edges.”

“The outcome of this analysis is threefold: (i) understanding how road networks are affected by different disruptive events, (ii) identification of the type of disruption to which each country is most vulnerable, (iii) pinpointing hotspots of road network vulnerabilities.”

Researchers have also developed a national road vulnerability index (NRVI) which allowed them to rank countries according to the vulnerability of their national road networks by combining the results of the targeted, local and random attacks for each country.

Their results show that the United States, China and India have some of the lowest network vulnerabilities. In contrast, Comoros, Bhutan and Trinidad and Tobago have the highest overall road network vulnerability.

Countries with the largest road networks are generally the least vulnerable to disruptions. However, some of the smallest networks are the most susceptible.

Among the most vulnerable countries are SIDS, such as Nauru and Saint Lucia, highly mountainous countries like Bhutan and Andorra, and some of the lowest-income countries, such as Somalia and Madagascar.