Road Network Operations
& Intelligent Transport Systems
A guide for practitioners!

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Work Zones

Work zones - due to road, bridge and tunnel construction and maintenance work have a negative impact on Road Network Operations. ITS and other techniques are used to minimise the negative impacts and keep traffic moving through affected zones as efficiently and safely as possible, for both for travellers and workers. This is especially important for night-time work, which is becoming increasingly common on the highways.

A number of measures are used to minimise worker exposure to motorised traffic and to safeguard road users from the construction and maintenance work. They include:

  • full road closures
  • ramp closures on highways
  • protection of work zones with traffic cones and crash barriers
  • extensive use of signs including Portable Dynamic Message Signs or VMS (PDMS)
  • median crossovers linked to contra-flow systems
  • lane control and narrow running lanes
  • full or partial detours or diversions
  • protection of work zone setup and removal operations using rolling road blocks
  • night-time or off-peak working when traffic volumes are lower
  • accelerated construction and maintenance techniques

Reactive Measures

Safety cannot be achieved by preventive measures alone. It is important to constantly monitor the traffic situation, weather conditions and the specific construction or maintenance activities taking place – and respond as necessary. This can be achieved through the establishment of an integrated traffic management and construction operations centre. Often a dedicated operations centre with tow-trucks for incident response is set up.

Lane Restrictions

In safe and stable traffic flow, traffic lanes must be observed so that proper segregation between vehicles of different speed is maintained. This can be done through the use of road studs, "cats eyes" or some other physical markers in the lane separation – which the driver will sense if the vehicle strays into a neighbouring lane. This may either trigger a warning or – in vehicles with advanced equipment – a warning could automatically lead to corrective action by the vehicle itself. Cameras or lasers, can be used to sense vehicle intrusion into closed lanes, which could otherwise endanger workers. (See Warning and Control)

Technology Data and Resources

ITS technologies provide many opportunities for monitoring and managing work zone operations – but are not a way of saving on fixed signing and traffic cones. ITS has benefits when signing and coning in preparation for roadworks – and when the roadworks are live and an incident occurs. A reliable source of power will be required, such as a portable generator.

ITS applications have been used to measure spot speeds in work zones. More recently APNR cameras are widely used to support average speed enforcement – with good compliance. Other ITS technologies are used to collect data that accurately reflects travel conditions through work zones – and, more recently, real-time monitoring of traffic conditions.

Use of ITS in work zones is not limited to urban areas. Temporary ITS devices, such as Portable Dynamic Message Signs (PDMS), Highway Advisory Radio (HAR), trailer-mounted cameras and sensors – can easily be deployed in a rural work zone where permanent ITS does not exist. Several commercial companies provide services that may include these devices, which communicate their data and images to a remote location where they are monitored (along with images from other locations). If issues arise, those monitoring the cameras can contact local law enforcement and transport officials who are able to respond.

In summary, ITS technology can be applied in work zones for the purposes of:

Many applications serve a combination of these purposes to:

  • detect when queues form to alert drivers about slower (or stationary) traffic ahead, so they can stop in time or take an alternative route
  • warn motorists that trucks are entering or exiting the work area to/from the running lanes at speeds much slower than the traffic flow
  • assist dynamic merging in heavy traffic to reduce queue length and allow maximum use of running lanes up to the point where lane restrictions begin
  • encourage drivers to merge early in lighter traffic to reduce conflicts
  • alert motorists to work zone journey times/delays so they can choose an alternative route, or enable the system to recommend or encourage diversion when delays or conditions are significant

Some regions have automated enforcement in work zones. The data and information necessary to support enforcement action can be collected from the use of Bluetooth, CCTV cameras, buying third party data and coordination with the TCC.

Advice to Practitioners

Most work zones are relatively short-term in nature, but some maintenance and construction work is long-term. Early deployment of ITS can be effective in supporting diversions, managing incidents and mitigating capacity reductions.

So-called “smart” work zones employ a combination of data sources to measure journey times through the work zones and are becoming commonplace in many countries. Real-time ITS supports a wide array of innovative applications that include active management of work zones based on observed traffic conditions. These capabilities are used to extend work hours and maintain acceptable journey times. Work is curtailed when journey times exceed certain thresholds. Work zone managers can be warned when travel speeds are dangerously high and a police presence may be needed.

“Smart” Work Zones in UK

In the UK work zone contractors have to limit their possession of the roadway for maintenance work during peak times. One innovative solution to this involves the use of Portable Dynamic Message Signs (PDMS) - with built-in traffic detection to monitor traffic demand. The ITS equipment allows the contractor to maintain lane restrictions longer – until the volume of traffic requires them to be removed. The increased time for site occupation allows longer work periods, improving productivity so that the works finished sooner. Motorists benefit from a reduction in the overall period of disruption.


Reference sources

Vithen, C. Use of ITS during Major Roadworks, Office for Traffic Management and ITS, Danish Road Directorate, Copenhagen 2007 (See

Federal Highways Administration Mitigating Work Zone Safety and Mobility Challenges through Intelligent Transportation Systems – Case studies (available for download at: