Road networks are traditionally designed to function efficiently and cost-effectively – but only if things go according to plan. Disturbances are usually not taken into account in network planning. Researcher Maaike Snelder is taking a different approach. She argues that to make networks more robust and travel times more reliable, network design should take into account contingencies.
Many things can hamper the flow of traffic. Accidents, extreme weather and road works can cause serious delays. Irregularities on the demand side, such as major events or public holidays, can also trigger congestion. For many years, scientists in densely populated countries such as the Netherlands have been trying to alleviate this problem.
Maaike Snelder at TNO is one of these scientists. During a previous research project, she designed an entirely new, hypothetical road network for the Netherlands. In this project she only looked at the problem from a transport point of view, disregarding factors such as cost, environment and liveability aspects. In fact she gave herself carte blanche. “This is of course not realistic,” Snelder indicates. “However, it did show us where the weaknesses lie in the today’s road network.”
Snelder’s current project focuses on the real-life situation. It aims to develop measures to make the existing network more robust. “We look at network design,” she specifies. “What is the quality of the underlying road network, and how can we make adjustments that allow it to function more efficiently and reliably? Are there any back-ups, for instance, and how can we connect different routes in a better way?”
Snelder develops models to predict the consequences of potential adjustments in the current road network, which allows her to play with different variables and elaborate different scenarios. “Some outcomes, such as the importance of a good network of secondary roads, may seem only logical, but they still need to be shown in a quantitative way. Now we can analyse objectively why certain measures work and others don’t.”