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

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Data Capture

ITS systems can provide a large amount of data that is relevant to accident analysis – such as data on weather and traffic conditions. Digital road maps may contain information on road horizontal curvature and slope in addition to other roadway information such as vehicle restrictions or number of lanes. In-vehicle data recording provides an additional source of information. Arrangements need to be put in place to archive this data for accident investigation and analysis.

Data Capture at the Scene of the Accident

Hardware advances in recently years have also improved accident investigation and recording (see the example, CRASH, in the display box below).  Similar systems include the Road Accident Data Management System (RADMS) developed by the World Bank and the Road Accident Data Recorder (RADaR) developed by the International Road Federation. 

CRASH – Collision Recording and Sharing (UK)

The CRASH electronic system used by police forces in England and Wales for data capture at the scene of collision combines digital technology with  information management. It enables secure collection, validation, transmission and storage of road traffic collision reports. It supports police business needs and the Department for Transport's statistical requirements.

CRASH is hosted on the Police National Computer and imports and exports data to and from other agreed agencies and their systems – such as the vehicle record at the Driver and Vehicle Licensing Agency. By providing automated access to complementary sources of information, it maximises the efficiency of police time when reporting an accident. A police officer only needs to record the vehicle’s registration number – rather than other details, such as  the make, model and colour of a vehicle, and the owner. Collision locations are more accurately positioned using built-in GPS receivers and interactive maps.

Data from Roadside Systems

Roadside systems can supply information on weather, road surface conditions and traffic flow. Video of the accident scene may be available from CCTV cameras and the Traffic Control Centre. The data can be transmitted to a national or regional Traffic Control Centre (TCC), which can then initiate appropriate action – such as dynamic speed limit management. For example, the TCC may set a temporary lower speed limit in response to adverse weather conditions or road accidents – and communicate this to the road users through a range of media, such as VMS or subscription based news/traffic channels.

Real time monitoring of traffic conditions via sensors and imaging technologies also support TCC operator awareness of unexpected events – such as road accidents and stranded vehicles – so they can take appropriate action. Video of the accident scene may be available from CCTV cameras and the Traffic Control Centre. (See: CCTV, Weather Monitoring, Vehicles and Roadways, and Traffic Control Centres)


Active Traffic Management (UK)

The Active Traffic Management (ATM) system in the UK consists of sensors buried in the lane to monitor traffic flow and speeds. If any abnormal patterns are detected, the TCC operator can confirm the incident by looking at CCTV images and setting the VMS systems – to show temporary speed limits or specific messages, as below. The ATM system was trialled on the M42 in 2003, fully implemented in 2006, and has gradually evolved into the current Smart Motorway system. (See Case Study)

Active Traffic Management Systems. Key: CCTV = Closed-Curcuit Television; AMS = Advanced Message Sign; ERA = Emergency Rest Area; HSR = Hard Shoulder Running; AMI = Advanced Motorway Indicator.

Data from in-vehicle systems

Tachographs and fleet management systems can provide data on driver hours of service and vehicle speeds. The use of video cameras as an integral part of fleet management systems is becoming more common. The camera view may be of the forward roadway only or it may also extend to a cabin (driver) view allowing investigation of driver attention in the pre-accident period. Fleets typically use such data for feedback to drivers, driver training and investigation following an incident. The saving of data for a time window is typically automatically triggered by an accelerometer that detects rapid acceleration or deceleration.

Event Data Recorders

So-called “blackbox” Event Data Recorders (EDRs) are mandated for other modes of transport such as civil aviation but are not yet required for road vehicles. The recorders provide enhanced quality and accuracy of accident data. Typically, they store recent data in short-term memory – and the memory store is replaced at frequent intervals. Once an event, such as airbag deployment, is detected, the data in the memory store is permanently saved. This will comprise information on the status of vehicle sensors and control systems which can be accessed from the vehicle’s Controller Area Network (CAN). Data can include information on speed, accelerator pedal position, brake activation, driver use of seatbelt, as well as use of on-board vehicle systems such as cruise control or speed limiter prior to and during an accident.

EDRs are already present in a large proportion of vehicles, including over 90% of light vehicles in the USA. There is a US standard for EDRs fitted in light vehicles (Code of Federal Regulations Title 49 part 563). It is intended to ensure that data from an accident is usable for accident investigation purposes and can assist in analysing the performance of advanced safety systems such as restraint systems. The standard specifies common requirements for EDRs in terms of vehicle information such as speed, accelerator position, brake application, engine speed and speed change through a collision. It also requires vehicle manufacturers to provide data retrieval tools. There has been extensive discussion, particularly in North America, about mandating the fitting of EDRs in all new light vehicles - but to date, no legislation has been enacted. (See Probe Data)

Advice to practitioners

Reliable accident reporting systems have value in enhancing understanding of conflict and behavioural issues and in identifying common causes of accidents and developing effective countermeasures.

Procedures need to be put in place to store and archive relevant data from roadside systems. There are privacy issues associated with data stored by fleet management systems and in-vehicle Event Data Recorders. In some countries the consent of drivers may be needed to access the EDR information unless there are legal provisions that provide rights of access in certain situations. (See Legal and Regulatory Issues)

Reference sources

Information from the US National Highway Traffic Safety Administration (NHTSA) about research on event data recorders is available at

The USA regulation on Event Data Recorders can be found at