Crash analysis system (CAS) - a road safety tool

Print version: Crash analysis system (PDF, 292 KB, 2 pages)

The Land Transport New Zealand's (Land Transport NZ) crash analysis system (CAS) is a vital tool in New Zealand's drive to reduce road trauma.

CAS is a tool that manages, analyses and maps traffic crash and related data. It is a computer system in which people can:

• enter road crash data
• select crashes for analysis
• map crashes
• view images of the crash report diagrams
• locate and map crash clusters
• report on crashes or crash clusters
• monitor trends at crash sites
• automate the production of collision diagrams
• identify high-risk locations.

The information CAS provides is used to help analyse and determine road safety funding allocations. It is also used in the targeting of road safety programmes and the monitoring of their performance. In this way CAS provides a platform for the development and implementation of new road safety initiatives, making a significant contribution to crash prevention in New Zealand.

Because it integrates mapping with other functions, CAS represents a significant advance over previous crash analysis systems. A key innovation is the ability to link crash and roading data.

CAS provides a platform for the development and implementation of new road safety initiatives, making a significant contribution to crash prevention.

What are crash analyses?

Crash data is extensively analysed at several different levels:

NATIONAL
eg trends in alcohol-related night-time crashes, or trends in truck crashes

LOCAL
eg crash trends on major local roads, or the location of wet-road crashes

DETAIL
eg the types and locations of crashes at a particular roundabout or intersection.

Typically, crash analysis is undertaken by selecting crashes and then using some of the many reporting tools provided by CAS. An example of this is shown on the reverse. The information provided by the reports allows Land Transport NZ and its road safety partners to identify problem areas and trends that can then be targeted.

Who analyses crashes?

Many organisations in New Zealand contribute to improved road safety through road crash prevention. Major users of crash data include Land Transport NZ, New Zealand Police, Transit New Zealand, local authorities, engineering consultants, ambulance services, fire services and road safety co-ordinators.

What crash information does CAS hold?

CAS integrates three primary sources of road safety data: crash reports, diagrams of crashes (from 1996 on) and roading data, which includes road categorisation and traffic flows. The crash data collection is based on the fatal, injury and non-injury crashes reported by the Police to Land Transport NZ.
Crash reports include:

• where the crash occurred
• when and how it happened
• who was involved
• the type of vehicle drivers or passengers were travelling in at the time of the crash
• the people involved who were not in vehicles
• information about the crash environment
• a crash diagram.

In the Road Safety to 2010 strategy the government has stated a goal of reducing annual road trauma to no more than 300 deaths and 4,500 hospitalisations by 2010.

Land Transport NZ then codes this information according to the type of crash movement involved (eg overtaking or right-angle intersection collision) and the factors contributing to the crash (eg driving too fast for the conditions or failing to stop at a Stop sign).

Until the CAS system was developed crash diagrams were held in microfiche or paper format. The diagrams are now scanned in, enabling users to instantly access them on-line — a useful tool when undertaking detailed analyses. CAS also holds scanned versions of the other pages from each original crash report.

Every year all road crash information is loaded into CAS. This can mean up to 30,000 non-injury crashes, between 9,000 and 10,000 injury crashes and up to 400 crashes involving death.

How is CAS linked to road information?

CAS has been designed to systematically link crash data with data from the road maintenance and management system (RAMM) used by all roading authorities in New Zealand. It achieves this by linking the road data to maps of the roads. Crash data is also linked to these maps, allowing road data to be combined with crash data.

CAS is an integral part of one of New Zealand’s most successful roading projects, the ‘black spot’ programme. The programme is a joint initiative involving Land Transport NZ and road controlling authorities. It was developed in 1985 to investigate all New Zealand roads, identify black spots and make improvements to them where necessary. CAS includes a system to track crashes at black spots and link site improvements to crash reductions. This allows reporting to roading authorities on the results of their remedial programmes, ensuring that the knowledge gained can be beneficial to others.

Mapping data

CAS utilises mapping data supplied by Critchlow Associates Ltd (www.critchlow.co.nz) who annually rebuild the links between the road maps and RAMM (see ‘How is CAS linked to road information?’ above).

The mapping data includes state highways, motorways, arterial roads, all roads, railways and railway stations, rivers and lakes, built-up areas, cities, towns, places of interest, territorial authority boundaries, regional government boundaries, census meshblocks and area units, Transit New Zealand boundaries, and police station, area and district boundaries.

When crash map co-ordinates are calculated by CAS, all the boundary-based information is automatically calculated, along with the crash location in terms of RAMM and the Transit route position. The latter two linkages allow CAS crash data to be used externally to CAS in other systems, and data from other systems to be linked to crash data.

Who develops and supports CAS?

Relational Technology International (RTI) (www.rti.co.nz) designed and tunes the database, and develops and supports the application.

Critchlow Associates Ltd provide the mapping data. They provide an annual update of the New Zealand-wide linkage between their road network and road maintenance data.

Unisys supports the database and Citrix environment that brings CAS to you.

How is CAS made available?

CAS is available over the internet, using the Citrix Metaframe Technology which will download the first time you connect to CAS. The CAS session seen by the user is actually running on a server at Unisys in Auckland, and the screen produced there is transmitted over the internet.

How can I find out more about CAS?

Please contact the CAS helpdesk at Land Transport NZ (see below) to obtain up-to-date information on CAS availability and conditions of use.

Email ISTService@nzta.govt.nz
Phone 0800 805 263
Fax 06 953 6412

Postal address:
IST Service Delivery
Private Bag
Palmerston North

To find out more about Land Transport NZ visit the website at www.landtransport.govt.nz

Using CAS - an example

CAS examples (PDF, 63 KB)

Page updated: 13 September 2005