Road Network Operations
& Intelligent Transport Systems
A guide for practitioners!
Road Network Operations
& Intelligent Transport Systems
A guide for practitioners!
The World Bank reports that every year, over 1.17 million people die in road traffic accidents around the world, most of them – some 70% – in developing countries. Two thirds involve pedestrians – and, of these, one third are children. Over 10 million people are seriously injured each year.
Road traffic accidents cost countries between 1% and 3% of their annual gross national product (GNP) - a particularly heavy burden on those with developing economies.
ITS applications have the potential to significantly reduce road traffic accidents and their impacts in various ways that reduce the number, frequency and severity of incidents. For example ITS applications can:
ITS technologies for improving road safety include:
Performance measures that can be used to assess ITS benefits can be direct or indirect.
Direct measures include overall crash rate, fatality and injury rates – for example, percentage reduction in collisions (but this is difficult to obtain empirically from operational tests since real accidents in field trials are infrequent)
Indirect measures include vehicle speeds, speed variability, the number of traffic violations, percentage reduction in rescue response time and public perceptions.
A few multi-year longitudinal studies have provided reliable before-and-after data on the impact of ITS on accident rates. For example:
Safety benefits from ITS go wider than measurable accidents. The confidence that travel is safe does not come only from measurable benefits such as reducing accidents or collisions and their consequences. The perception of personal safety is also important. Many countries now have policy priorities relating to perceptions of personal safety, whether that is nervousness about traffic, crime, isolation or a wider perception of community safety.
People are frightened of traffic, even if they have never been involved in an accident or collision. This fear has societal costs. ITS can:
Access control and area management schemes have been successful in improving the quality of city centres. For example, in the 1990s, ITS-based security measures in the City of London significantly reduced the number of accidents involving pedestrian.
A number of ITS-enabled measures and technologies have an important part to play in delivering safety benefits.
One of the driving forces behind the development of ITS in Europe has been the level of road traffic accidents across the continent.
The European Commission estimates that there are some 100 million cross-border road trips annually within the European Union (EU), and that foreign drivers account for 5% of traffic – but commit 15% of speeding offences. EU countries work together on cross-border road safety enforcement.
Since 7 November 2013, most EU countries have been implementing cross-border enforcement for the riskiest traffic offences – such as, speeding, failing to stop at traffic lights, failure to use seatbelts and drink driving. These account for 75% of road traffic accident deaths in Europe. The enforcement scheme operates through ITS-enabled electronic exchange of national vehicle registration data with other countries. It is estimated that public awareness of the increased likelihood of offenders being caught will save between 350 and 400 road traffic accident deaths a year.
Red-light running is a major traffic safety issue. In the USA, it is accounts for some 800 deaths and an estimated 165,000 injuries a year. Automated camera enforcement provides the evidence necessary for prosecution.
The city of Bologna in Italy has tested an automatic enforcement camera-based system (known as STARS) to help detect traffic light offences and issue fines for non-compliance. The images are stored as a source of court evidence and for statistical evaluation.
Following its installation, accidents fell by 21% and injuries by 28% at all equipped crossings. The number of fines initially increased significantly - by 88% over the period between 2008 and 2011 - but subsequently stabilised. In comparison with data from the year before installation to August 2011, there was a total reduction of 40% for accidents and 48% for injuries.
Drivers, who did not know where the STARS system was active showed increased caution at all intersections – extending the beneficial effects of the technology while reducing its installation costs.
Speed enforcement is becoming more sophisticated and driver-friendly. Conventionally the main technique has been the use of single-point “spot” speed cameras, which record the driver exceeding the limit as they pass by. In the UK, speed cameras of this kind have often drawn hostility from motorists who perceive it as an unfair means of raising money from enforcement fines.
Speed over distance (SOD) or average speed enforcement (ASE) are seen as fairer methods.
Average speed enforcement is demonstrating higher levels of compliance than spot-speed in a number of European countries where it has been deployed.
“Soft” speed enforcement aims to influence driver behaviour – it does not impose legal or financial penalties. A European example involves detecting a vehicle as it approaches from a measured point ahead, which allows the time needed to cover the distance to be calculated to determine whether the vehicle is speeding. This can trigger a dynamic message sign to display a warning message. (See Vulnerable Road Users)
Many countries are introducing and enforcing 32km/h speed limits in urban areas – to protect vulnerable road users, such as children. In Chicago, USA, where 800 out of the 3,000 pedestrians hit by vehicles each year, are children, and signage is ignored by 10% of motorists – the system lowers camera speed triggers during enforcement hours More information here: http://www.cityofchicago.org/city/en/depts/cdot/supp_info/children_s_safetyzoneporgramautomaticspeedenforcement.html)
Beneficial ITS vehicle technologies include:
The basis of all these systems, and the safety benefits that they bring, is the development of on-board sensors linked to the vehicle’s engine management and braking systems. (See Driver Support)
Anti-lock braking systems (ABS) intervene to help stop loss of vehicle traction (skidding – for example, in icy weather or wet conditions). ABS works closely with electronic stability control (ESC), which detects the loss of steering control and applies the brakes individually to the wheels to correct the steering. The US Insurance Institute for Highway Safety and the US National Highway Traffic Safety Administration estimate that comprehensive use of the technology could avoid one-third of fatal road traffic accidents.
Crash avoidance systems use autonomous braking, which comes into effect if a driver fails to brake in time. The technology is an advance on the (widely-used) autonomous cruise control, which automatically adjusts a vehicle’s speed to keep it a safe distance behind traffic ahead. Both the US and the EU are moving towards making mandatory, the fitting of frontal collision warning systems. Automotive manufacturers have started to include these systems into their production lines. The EU estimates that these will save 5,000 deaths and 50,000 serious injuries a year.
Automatic parking uses sensors to detect the presence of objects around a vehicle to guide the vehicle safely into a clear space.
Driver drowsiness detection is a response to studies that suggest that up to 20% of road traffic accidents are due to fatigue. It works by monitoring a vehicle’s movements and assessing the likelihood of these being controlled or uncontrolled.
The main ISA options are:
Trials indicate the potential for safety, efficiency and improvements – including 42% reductions in fatal crashes, fuel efficiency gains of 5%, and smoother traffic flows resulting in less congestion (See: http://www-nrd.nhtsa.dot.gov/pdf/esv/esv20/07-0247-W.pdf).
Widespread adoption of ISA could bring the additional benefit of reduced insurance costs. In Europe, ISA systems that meet European New Car Assessment Programme (Euro NCAP) requirements gain an advantage in relation to the car’s overall ‘Safety Assist’ rating.
Automatic Incident Detection (AID) systems use cameras and traffic monitoring technology to record and analyse traffic data and quickly detect incidents using motorway incident detection systems. A sudden build-up of congestion, for example, can indicate that there is an incident ahead.
Response times to road traffic accidents and medical emergencies are critical, with the ‘golden 15 minutes’ typically cited as the optimum window for early and effective treatment. The key needs are fast response and accurate direction to accident scenes. Automatic traffic signal priority for emergency vehicles is increasingly common.
ITS technologies introduced to speed up the process include automatic crash notification systems, which many automotive manufacturers are building into their vehicles. These work by sensing an impact and sending out an automatic alert via mobile phone networks to a call centre. In Europe, the EU’s eCall (emergency Call) initiative aims to mandate, from 2018, European automotive manufactures to install these systems.
Emergency service providers can make use of real-time dynamic route guidance systems to dispatch and route vehicles around known congestion and roadworks to minimise response and return times. Speeding ambulances, themselves, risk causing, or being involved in, road traffic accidents. The US General Services Administration records over 6,000 ambulance crashes a year. In-vehicle ‘black boxes’ can monitor and record driver behaviour and highlight training needs.
Workzone traffic management schemes can draw on ITS technologies such as Bluetooth detection, which anonymously registers the passing of vehicles carrying Bluetooth devices (See Wireless Telecommunications). This provided the US state of Texas with a cost-effective alternative for monitoring the speed of vehicles over a lengthy section of road reconstruction on the I-35 highway.
There are examples of basic roadworks equipment being equipped with ITS features to provide a safety role. For example:
In rural areas, intersection crashes typically occur less often than in urban ones. They are often more severe because of the higher vehicle speeds and the consequences can be more serious because of longer emergency response times. New intersection decision support systems use traffic sensors and advanced computing to monitor vehicles moving along rural divided highways (dual carriageways). They process the data generated to alert drivers waiting to merge with, or cross, the traffic – when the gaps are too short for them to be able to do so safely.
In Australia, where about 60% of all fatal road crashes occur on rural roads, there is research evidence that electronic stability control (ESC) can help avoid crashes on high-speed routes, by detecting when a vehicle is at risk of skidding and applying preventive braking interventions to individual wheels. In 12 modelled crash scenarios developed from data on actual crashes, ESC prevented collisions in 10 cases and reduced their severity in the other two.
Collisions with wild animals on rural roads are increasing wherever human development spreads. This is an issue of growing relevance to developing and emerging economies. A crash involving a large animal can cause death, serious injury, severe vehicle damage and disruption to other road users. Physical defences such as fencing and over/underpasses are not always possible or cost-effective, given access and maintenance issues. In-vehicle and roadside systems are being developed to detect large animals. The sensors can distinguish between moving vehicles (with warm engines) and animals, alerting drivers to their presence (See Information and Warning).
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