Road Network Operations
& Intelligent Transport Systems
A guide for practitioners!
Road Network Operations
& Intelligent Transport Systems
A guide for practitioners!
“Cooperative Systems” use communication between vehicles and between vehicles and the infrastructure (roadside equipment and traffic control centres) to provide drivers and other road users with real-time information. Vehicle-to-vehicle (V2V) communication applications include Cooperative Cruise Control and vehicle platooning (where vehicles are coupled into platoons with an “electronic tow-bar”). (See Coordinated Vehicle Highway Systems)
Vehicle-to-Infrastructure (V2I) applications have an important role to play in road safety by gathering, processing and exchanging information on traffic and road conditions from different sources on the network (locally and regionally) to develop information warnings and vehicle control instructions. For example vehicles can be alerted to slippery road conditions where the trigger might be icy road sensors at an exposed location or a skid registered by a vehicle.
Currently cooperative systems tend to be expensive. That is because the technology requires high bandwidth and very reliable and rapid (low latency) communications - which are costly. Specialised wireless communication, known as DSRC (Dedicated Short Range Communications) is potentially the high-end emerging standard. It uses a microwave or infrared communications with added security features. It is likely that DSRC cellular communications for V2I/I2V systems and services, will only be economically feasible in so-called "hot spots" of the road network such as tunnels, accident black spot intersections, signal-controlled intersections.
Besides the cost, a major obstacle to the use of cooperative systems, particularly V2V systems, is that there is little benefit to early adopters. Unless there are other equipped vehicles with which to communicate, the technology cannot interact. This is in contrast to autonomous systems such as Forward Collision Warning or Lane Departure Warning, where the equipment can have immediate benefit for the driver.
Cooperative Systems in the USA
The United States National Highway Traffic Safety Administration (NHTSA) has announced that it is considering requiring new vehicles to have connected vehicle (V2V) capability using DSRC. The expectation is that mass production will lower the cost of the V2V communication units and that government will develop a programme for installing DSRC roadside infrastructure.
V2V technology has the potential to be fused with existing vehicle safety features to further improve the effectiveness of many crash avoidance safety systems currently being developed and implemented in the vehicle fleet - and will serve as a building block for a driverless vehicle. Vehicles equipped with V2V technology could also enable the development of a wide range of mobility and environmental benefits based on vehicle-to-infrastructure applications and other V2V applications that can enhance traffic flow in many ways. V2V technology does not involve collecting or exchanging personal information or tracking drivers or their vehicles.
There are also moves to develop cooperative systems that use readily available technologies such as GPS combined with 3G and 4G mobile communications. One example is TomTom’s “Jam Ahead Warning” system, which alerts drivers to slow-moving traffic ahead of their current position. The system uses the real-time speed profile of users of TomTom navigation devices that are fitted with mobile data communications. The system identifies in real-time when traffic speeds are unusually slow and broadcasts an alert to other vehicles fitted with TomTom units in the locality. The advantage of autonomous systems such as this is that they can be implemented immediately without the requirement for installing expensive dedicated communications technology and infrastructure.
Other cooperative systems being trialled use roadside equipment to communicate with drivers. An example is intersection collision warning. Many proposed applications of cooperative systems are comparable to current use of Variable Message Signs. There is scope also for the development of safety applications based on Human-to-Vehicle (H2V) communications.
Safety at unsignalised intersections can be a major concern. Intersection collisions are one of the most common types of crash and tend to be severe particularly on rural roads. That is because collision speeds are often high and occupants are less well protected against side impacts compared to frontal collisions. The high speed of main-road traffic can exacerbate the situation.
Many rural intersections use static stop signs or give-way (yield) signs to control side-road traffic. The driver has to judge when there is a safe gap to join the main road traffic. Only the nearside gap needs to be assessed when the driver is not crossing the near-side traffic flow. Where the driver needs to cross the traffic flow, the task becomes more difficult. Multilane roads increase the difficulty.
Intersection collision warning systems use multiple sensors installed at the roadside to track vehicles as they approach, linked to sophisticated algorithms that determine whether gaps in the traffic are safe or unsafe (above or below a critical threshold). Signs to help the driver decide whether to make the manoeuvre are located where they can be seen by drivers at the stop or give-way sign – such as in the photograph in the box below.
Cooperative Intersection Collision Avoidance System (CICAS)
The University of Minnesota has developed the Cooperative Intersection Collision Avoidance System (CICAS) to improve safety of vehicles turning into or crossing rural divided highways. The initial development was in a driving simulator, followed by real-world implementation.
CICAS informs drivers at stop-signs when gaps between vehicles approaching on the main road are not large enough - see http://www.its.umn.edu/Research/FeaturedStudies/intersections/cicas.html.
The warning system is deployed at three intersections in Minnesota and one in Wisconsin - at high-risk locations. The Minnesota Department of Transportation is rolling out a refined version of the system to intersections across the state (2012-2015). It is known as the “Rural Intersection Conflict Warning System” (RICWS).
Detailed information on the development of CICAS can be found at http://www.its.umn.edu/Research/ProjectDetail.html?id=2006050.
Currently most vehicle protection systems for Vulnerable Road Users (VRUs) are based on forward looking cameras mounted on the vehicle, used in conjunction with other in-vehicle safety applications such as Forward Collision Warning. As mobile communications mature at a rapid rate there is potential to develop safety applications based on Human-to-Vehicle communications. (See Vulnerable Road Users(ITS & Road Safety) and Vulnerable Road Users(Human factors)
To be reliable, the technology needs to be able to detect, classify and track relevant objects and disregard false alerts. The technology also needs to be readily accessible - at an acceptable cost for the user, wearable, easy to use and have low power consumption. In addition, the technology needs to cope with complex situations where people are obscured by other objects such as parked vehicles. In-vehicle equipment must have the ability to detect pedestrians or cyclists at intersections where a high proportion of incidents occur.
If Human-to-Vehicle communication systems are to be successful, the take-up needs to be relatively high. The technology is near-market so there is need for decisions on the appropriate user communication interface. For example:
Human-to-Vehicle Communication Developments
Approaches which combine video detection on the vehicle with real-time positioning systems for the vulnerable road user are being developed to provide warnings of each other’s presence. For example cooperative sensor technology via RFID tags can be integrated into school bags, clothing, helmets or mobile phones. In-vehicle location devices can transmit a continuous query to the RIFID tags to obtain information on the location, trajectory and speed of the road user. The objective is to calculate risk and warn of a possible collision. An example is Japan’s Pedestrian Information and Communication System to enable the elderly and the disabled to move around safely.
See: http://www.utms.or.jp/english/system/pics.html
Smart phones offer another promising platform and a communication interface for new applications.
Privacy issues – which may be sensitive for some user groups, such as children and vulnerable adults - will need to be addressed. Whilst a RFID tag may not identify a specific person, public concerns may be high and lead to low uptake of applications.