Traffic Engineering Reimagined

Throughout my career, I have noticed that the traffic engineering profession is often singled out for criticism when it comes to urban road space being reconstructed and used as a place for motor vehicles. The negative sentiment persists even today and in the context of implementing EV (Electric Vehicle) strategies and preparing for CAV (Connected and Automated Vehicle) deployment.

So, to stay relevant and continue to make a meaningful contribution to society, should the profession look at redefining itself - or simply changing its name to (Road) Transport Engineering to reflect a more multimodal approach?

Below are a few thoughts of mine. But first let's clear up the misconception!

Design and operation of a road and street network is primarily influenced by public demand of predominant users

Tracing the evolution of the discourse surrounding urban street value and changing public expectations over the 20th century, I argued in the Transport Reviews article (coauthored with Douglas Wilson and Roger Dunn ) that:

It was the society as a whole ... that determined the function, design and use of a public road network predominantly for motor vehicles.

In other words, the predominant functions of road and street space reflect the expectations and values of society at a given time. It is, therefore, not reasonable to assume that a single profession, such as traffic engineering or road design, could be solely responsible for creating a street environment that is heavily centred on automobiles. Instead, the multidisciplinary design and use of roads and streets (see Figure 1) as a network of public space is shaped by a variety of environmental, social, economic and political factors.

To integrate or segregate road users with differing levels of kinetic energy is context-sensitive and place-based

Traditionally, traffic engineering has emphasised the segregation of different road users, particularly between higher speed, larger mass motor vehicles and pedestrians or cyclists, in order to minimise the risk of conflicts and improve traffic safety and efficiency.

However, there must be a threshold, you'd say, in the road and street design spectrum in which traffic efficiency is no longer the primary focus and as such integration of different road users is encouraged.

One approach to determine thresholds at the network level is philosophically outlined in the Traffic in Towns report. As depicted in Figure 2, the cellular concept involves an interlacing network of distributory roads that connect and integrate environmental areas with their own local and access roads. These areas must be a good environment where people can live, work, shop and move around on foot easily.

In NSW, roads and streets within an environment area would be categorised as main streets, local streets and civic spaces in the Movement and Place Framework. This Framework is supported by the TfNSW Road User Space Allocation Policy that takes into account both physical and temporal (dynamic, time of day) considerations when allocating road space.

In this context, the role of a traffic practitioner may shift towards that of a place-based practitioner, whose focus is on designing and managing roads and streets as more than just corridors for movement of people and goods, but as integral parts of the community and the broader built environment.

In an environmental area, residential or mixed-use, the implementation of an area-wide speed management system with a default speed limit of 30 km/h (as shown in Figure 3) can support the integration of road users with varying speeds, such as pedestrians, cyclists and users of micromobility devices. This approach allows these users to share or be in closer proximity to one another when using the road space, and it aligns with the Safe System approach, which aims to minimise harm by addressing the contributing factors that lead to fatal and serious injury crashes.

David McTiernan and I proposed some guiding principles for implementing 30 km/h speed limits and zones in a Journal of Road Safety article.

Whether a traffic professional serving as a traffic specialist or technical coordinator, or both, depends on the context in which they are working

The specialised fields of traffic signal design & operations, traffic control devices, highway design, smart motorway operations, traffic modelling and road safety will continue to be the primary focus of traffic engineers working on designing and managing a higher-energy road network (of main roads in NSW) outside environmental areas.

For projects or work within environmental areas, traffic practitioners should function more as technical coordinators, collaborating with other disciplines to create well-designed, lower-energy road and street environments and being open to new approaches and ideas.

To be a well-rounded traffic coordinator, it is important to have a strong foundation in a variety of technical practices and understandings. In an Austroads research report, Asif Hassan and I explored some of the key knowledge and principles (as shown in Figure 4).

I hope you enjoyed reading this, and welcome any feedback or suggestions. As usual, I should note the opinions expressed here are my own and do not necessarily reflect the views of my employer, Transport for NSW . Thanks!