Dealing with Unexpectedness


How should we deal with traffic incidents at critical times and locations, which cause major, unexpected problems for users?

Operators of road traffic networks are under increasing pressure to maintain acceptable levels of service, with declining resources and competing priorities. Urban traffic networks are not able to keep pace with the growth in travel, as a result major roads operate at maximum capacity for extended periods.

At capacity the strategic traffic network is very sensitive to changes in operating conditions, with major traffic incidents like crashes, rollovers and breakdowns, resulting in gridlock and community backlash. A study of unexpected events on a Brisbane motorway found that travel time increased 250% for example.


A typical strategic transport objective is the effective and efficient movement of people and goods to support economic activity, address social outcomes and reduce environmental impacts.

This can be translated to – maximising throughput of high value users, such as public transport passengers and freight. High value relates to maximising return on infrastructure assets to achieve desired transport outcomes.

Governments also aim to improve customer service, by providing consistent safety, reducing delays and improving reliability of travel. Private toll road operators, on the other hand, have a commercial imperative to provide good customer service, to ensure patronage and revenue growth.


Road users want to travel to a destination with safety, in an acceptable time, at a reasonable cost, without unexpected delays and have access to useful information on what is happening on the network. Traffic managers therefore need to have an increased customer focus, to improve reliability and minimise the impact of unexpected incidents.

Urban traffic networks are managed by various public and private operators, with different objectives and priorities. Users don’t really care who manages the network.


Traffic incidents result in unexpected delays, which have real, and perceived, costs for users – especially the ‘high value’ users such as trucks (both long-haul freight and pickup and delivery) and buses (mass people movements).

The key factor in any consideration of traffic operations is that unexpected delays have a perceived value of 2.5 times greater than expected delays. [1]

Value [Unexpected Delay] = 2.5 x Value [Expected Delay].

Unexpected delays therefore must be the primary consideration when establishing policies, strategies and priorities for traffic and incident management.


Improving customer service in traffic operations then means having a laser focus on reducing unexpectedness. A combination of rapid response and clearance of traffic incidents, managing traffic diversions and providing useful and timely traffic updates are strategies to achieve this. Note that providing information doesn’t necessarily change the length of the delay, but removes the angst of not knowing what is happening.


The Citylink toll road, operated by Transurban, is an example of good practice. The operator is committed to improving the safety, on-road experience for motorists and customer service, which means rapid response and communicate to users on any delays. Citylink has set a scorecard target for response vehicles to attend incidents in a traffic lane in less than 10 minutes on average and actual times have been less than five minutes over the past four years. [2]


Many Australian state governments have been outsourcing components of traffic incident management, starting with towing contractors, and progressively moving through the various aspects of incident management.

In Brisbane the automobile club (RACQ) won the contract to provide incident response and clearance services. They have a long history of successfully servicing member’s vehicle breakdowns and providing responsive services.

However, there have been concerns in the provision of incident management services beyond the initial response. Road maintenance crews have provided temporary signing, traffic control and diversions and clean up. Previously government transport agency staff provided these services, but there has been a recent trend in Sydney and Brisbane metropolitan areas for these services to be outsourced.

The challenge is that maintenance and incident response services have very different requirements, due to differences in customer service mindset and criticality of incident clearance times and there is a concern the level of service currently being provided needs considerable improvement. Contrast this to the toll road operators, who are responsive due to commercial imperatives. To overcome these challenges requires qualified experienced contractors with commercial incentives and accountabilities.

Rapid response and clearance of traffic incidents and provision of real-time information should be mission critical core business for traffic operators to reduce unexpectedness and improve customer service.

[1] Small K.A. et al. 1999. Valuation of Travel-Time Savings in Predictability in Congested Conditions for Highway Use-Cost Estimation, NCHRP Report 431, Transportation Research Board Washington DC. USA

Article first appeared on

Leave a comment

This site uses Akismet to reduce spam. Learn how your comment data is processed.