Road Network Operations
& Intelligent Transport Systems
A guide for practitioners!
Road Network Operations
& Intelligent Transport Systems
A guide for practitioners!
A number of ITS developments in the automotive sector are focused on improving the safety of the road transport system by complementing, or enhancing, drivers’ abilities to maintain alert and in control of the vehicle – and improving the accident avoidance performance of vehicles. A major motivation in their development is recognition of driver error as a major factor in the majority of car accidents. Developments in this area are moving towards the concept of self-driving cars and automated vehicle-highway systems. Examples of this type of safety-related ITS applications include: (See Driver Support)
The automotive industry has been working on a variety of collision avoidance systems that are either already in production or close to market. (See Warning and Control) These systems include:
These systems monitor the separation distance between vehicles and warn drivers when sensors detect another vehicle that may be dangerously close. If the driver does not react appropriately, automatic vehicle control actions may be initiated. Examples of these systems are already installed in the vehicles of some automotive manufacturers, such as Mercedes and Volvo.
Advanced Emergency Braking Systems (AEBS) detect the possibility of a collision with the vehicle ahead and warn the driver – using visual, audio or tactile feedback. If the driver takes no action, the system automatically applies the vehicle's brakes. At lower speeds AEBS acts to prevent a crash – at higher speeds it will reduce the severity.
Adaptive Cruise Control (ACC) tracks the vehicle in front, and automatically maintains a desired minimum distance (or time headway) from that vehicle. So long as this minimum distance is maintained, the vehicle will travel at the set speed. If the separation distance falls below this minimum value, the ACC system adjusts the vehicle’s speed to regain the minimum headway (in time or distance).
These systems detect slow moving or stationary objects and pedestrians that are in the path of a vehicle that is reversing – and warn the driver accordingly. Detecting these objects requires the use of relatively short-range sensors on-board the vehicles, such as a rear-view camera. Examples of these systems can be found fitted to many of today’s vehicle models.
Lane departure systems aim to help drivers avoid accidents that could result when a vehicle leaves its own travel lane and strays into the path of a vehicle in another lane. This is achieved by warning drivers and/or assuming temporary control of an at-risk vehicle. Among the most well-known of these systems are:
ITS technology has been tested in applications that will avoid, or to decrease the severity of, collisions at intersections. These systems track the position and status of vehicles within a defined area on approach to an intersection through the use of vehicle-to-vehicle communications and/or vehicle-to-infrastructure communications. If a potentially dangerous situation is detected that is likely to lead to a collision warning messages are delivered to the driver – for example, in cases where a vehicle fails to stop at a red light or attempts to make a turning manoeuvre in the absence of an adequate gap.
ITS applications have been developed to help eliminate and/or reduce the severity of accidents that result from poor visibility – such as night driving, heavy rain or foggy conditions. These systems include in-vehicle sensors that can capture images of the driving environment and display them graphically to the driver, for example through a head-up display. One example that illustrates the concept is the Driver Assistance System for Snowploughs developed by the University of Minnesota http://www.lrrb.org/media/reports/200313.pdf).
The goal of safety readiness ITS applications is to eliminate and/or reduce the number of collisions caused by impaired drivers (though tiredness, alcohol or drugs), a failure of vehicles’ components, or any degraded infrastructure conditions that could affect the safety of the vehicle. Systems are available that monitor the performance of the driver – and either warn or assume temporary control of the vehicle if a driver’s performance is impaired. Other systems monitor the performance of critical components of a vehicle (such as the braking system), and warn drivers of their imminent failure. There are also systems that can monitor the roadway and provide warnings to the driver of unsafe conditions – such as loss of tire traction on wet or icy road surfaces. (See Policing/Enforcement and Warning Systems)
Pre-crash restraint ITS applications anticipate an imminent collision and activate the appropriate passenger safety systems prior to the actual impact. For example, sensors are available to detect the rapid closing of distance between the vehicle and an obstacle. On detection, the system attempts to reduce the danger of the impact of the collision by settings restraints to absorb or dissipate the force of the impact – such as triggering an airbag. (See Partially Automated Driving)
A long-term goal of vehicle safety systems is a fully automated highway-vehicle system (AHVS) – where specially equipped vehicles travel, under fully automated control, along dedicated highway lanes – or where a self-driving vehicle pilots itself through mixed traffic. The AHVS concept has the potential to significantly improve the safety, as well as the efficiency, of highway travel by reducing the number and severity of crashes, decreasing congestion, and reducing vehicle emissions and fuel consumption. (See Automated Highways and New Applications)
The safety risks associated with AHVS operations need to be analysed carefully so that the risk of mal-function is minimised. Many automotive manufacturers are currently involved in significant research and demonstration projects aimed at making autonomous (or self-driving) cars, a reality. A number of countries are preparing to test the readiness of driverless cars. Nissan, for example, has promised the production of autonomous cars by 2020 – and Google has sponsored the development of a self-driving car. Initiatives from public and private enterprises may help accelerate the deployment of self-driving cars. An example is here: http://www.autoblog.com/2013/08/27/nissan-promising-autonomous-car-production-by-2020/ (See Warning & Control)
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