Road Network Operations
& Intelligent Transport Systems
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Warning and Control Systems

An increasing number of vehicle-based solutions that can warn the driver about impending safety risks are installed by automotive manufacturers in new vehicles – and some aftermarket devices are also available.

Infrastructure-based systems, which require communication exchange between the vehicle and roadside to provide warnings, are also being explored. Examples include intersection collision warning and Signal Phase and Timing (SPaT) Warnings. (See New and Emerging Applications and Warning Systems)

Vehicle-based warning systems can help drivers to avoid accidents. Their use in freight and public transport vehicles offers significant safety benefits and has the potential to accelerate more widespread deployment. Legislative options to require their deployment in these vehicles are under consideration.

The USA’s National Highway Traffic Safety Administration (NHTSA) has developed a classification for autonomous vehicles – that scores them on a scale of 0 to 4, depending on their level of automation:

  • Level 0 – No-automation – the driver is in complete and sole control of the primary vehicle controls (brake, steering, throttle, and motive power) at all times, and is solely responsible for monitoring the roadway and for safe operation of all vehicle controls
  • Level 1 – Function-specific Automation – the driver has overall control, and is solely responsible for safe operation – but certain functions are designed to assist specific driving tasks – such as electronic stability control (ESC), Adaptive Cruise Control and pre-charging the brakes in an emergency situation
  • Level 2 – Combined Function Automation – where a vehicle has at least two automated systems designed to work together (such as adaptive cruise control and lane centring)– but the driver is still responsible for monitoring the roadway and safe operation
  • Level 3 – Limited Self-driving Automation – where a vehicle can handle all driving functions – but the driver is expected to be available to take occasional control with sufficiently comfortable transition time
  • Level 4 – Full Self-Driving Automation – where vehicles are fully automated to perform all safety-critical driving functions and monitor roadway conditions for an entire trip – the driver provides destination or navigation input, but is not expected to be available for control at any time during the trip.

Connected Vehicles

Connected Vehicle Systems have become a key part of strategies to improve transport safety and efficiency in many regions. Several major field operational trials of the technology have been launched around the world over the last few years – in Europe, Japan and the USA – and others are planned. Collaborative discussions across regions are helping to accelerate development of systems. Regulatory authorities are monitoring the results and considering how best to support deployment.

At the simplest level, connected vehicle technologies fall into three major categories:

  • on-board devices
  • roadside devices
  • back-end systems – including security and data management capabilities.

Interactions may take place between any of the components – vehicle to vehicle (“V2V”), and vehicle to infrastructure (“V2I”) – and are standardised to allow any vehicle to link to any other vehicle or to any roadside unit. The figure below is an example of the key syetms, components and their interactions.


US Connected Vehicle Core Systems


The primary focus of connected vehicle technologies has been on short range communications capabilities – which are optimised for very low latency (transmission delay) in support of safety applications.

There is a very broad range of applications which can be built on top of this framework, including – safety solutions such as collision avoidance, mobility solutions such as enhanced traveller information, and eco-solutions such as signal optimisation.

A fully networked transport system may allow much more fine-detailed management of traffic flows. Experimental systems which communicate from the roadside to the vehicle, the recommended speed and acceleration – based on environmental factors such as congestion and roadway geometry –are being tested in Japan under the ITS Green Safety initiative. (See

Partially Automated Driving

The sensors required to enable vehicle warnings are increasingly being integrated into more sophisticated systems within the vehicle to automate certain driving functions. Drivers must still actively manage the driving process – but the vehicle can temporarily control functions such as braking and steering – either for the drivers’ convenience or to assist in an emergency situation. These systems can help avoid accidents and optimise the driving task by improving fuel efficiency.

The evolution from non-assisted driving to partially automated driving holds challenges that will need to be addressed during the transition to more and more highly automated vehicles:

  • drivers risk becoming over-reliant on new capabilities and their driving skills may deteriorate leading them to push their vehicles beyond their safe boundaries
  • newer drivers may not learn the skills necessary to drive older vehicles which are not equipped with the automated systems they are used to
  • drivers switching between vehicles automated and no-automated vehicles may not react to road situations in a manner appropriate to the capabilities of the car they are driving

Fully Automated Driving

Fully automated driving involves vehicles that can operate on public roads with no driver intervention. Many consider that removing driver control has the potential to dramatically improve travel safety, mobility and efficiency. For example, machine-driven vehicles may:
  • cause fewer accidents – because they can more reliably and quickly respond to emergency situations
  • increase roadway capacity – because they can safely drive faster and closer together than vehicles controlled by a drivers
  • improve mobility for the elderly and the disabled

There are many unknowns about the impact of large numbers of fully automated vehicles on the overall road transport network. While significant benefits are expected, there will also be many operational challenges. It is too early to determine exactly what they will be – and it is anyway likely be some time before such large scale deployment occurs. There is a lot of research being undertaken to understand the issues – with most major automotive manufacturers performing trials, as well as a number of publicly and privately funded initiatives. The availability of highly – and eventually fully – automated vehicles needs to be taken into account by transport planners.


Reference sources

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