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Crash Analysis System (CAS) - differences and user guidance

The following information describes differences within the new Crash Analysis System compared to the current system, and guidance on how to use the new functionality.

These changes are being introduced with the new CAS reporting system. The items listed in this section explain how they have been rationalised, to help avoid any confusion when using the fields in the future.

For any clarification or further support please contact the CrashHub project team – casreplacement@nzta.govt.nz

Road curvature

The existing values of ‘straight’ with three separate types of curvature have been rationalised down to simply straight or curved.

The existing curve variations will disappear from the system and be migrated into the new single curved value.

Vehicle type and vehicle usage

Vehicle type field also included values that were really vehicle usage, such as taxi or school bus. A new vehicle usage field will exist where these values can now be found.

Migration has mapped taxis as being a ‘car/wagon’ in vehicle type and vehicle usage as ‘taxi’. school bus was migrated as a ‘bus’ in vehicle type and ‘school bus’ in vehicle usage.

User selection impact: When querying for school bus, taxi or rental, use vehicle usage field, not vehicle type.

Ethnicity

As part of their mobility in the field programme, the police rationalised their ethnicity list. CAS naturally must follow suit. In practice, the main change is that specific pacific island entries for Fiji, Samoa, Cooks, etc. have been merged into a single general Pacific Islander entry by the migration process.

Current ethnicity table

Ethnicity code Description
E European
M NZ Maori
S Samoan
F Fijian
T Tongan
R Cook Islander
N Niuean
K Tokelauan
P Other Pacific Islander
A Asian
O Other
space Unknown
C European

 

New ethnicity table

Code Description
E European
M Maori
P Pacific Islander
A Asian
O Other
space Unknown
D Indian
L Latin American/Hispanic
T Middle eastern
F Native African

Movement code changes

The ‘lost control on bend’ row of movement codes (i.e. row ‘D’) has seen some expansion. The existing codes of ‘lost control on right hand bend’ and ‘lost control on left hand bend’, have been made more granular by each being given three variants: namely , finished up on road, finished up on left of road, and finished up on right of road. So where we used to have two choices we now have six. The ‘lost control at end of road’ code remains unchanged.

One issue is that, because the new variants on the existing codes are more granular, it is not possible to map old crashes into these new, more detailed, values meaningfully. To manage this, the original more generic ‘lost control on curves’ codes will be retained in the system, but no longer used for future crashes.

This may mean that when querying crashes that cover the changeover period you may need to use the old and new codes to get a complete picture, if that is the are you are investigating.

Vehicle make and model fields

In the existing CAS, there is a free text field that contains a description of the make and model of the vehicle. There is no validation on this field so there is a large variant in spelling of standard vehicles, such that it cannot reliably be used as a field for querying.

In the new system, the police will select the make, and then the model, from lists. i.e. two separate fields, with managed values. This ensures a consistency of reporting that allows this field to be used meaningfully in queries, going forward. For historical crashes, this will be less useful. The migration process has attempted to interpret the overall text present and split it into the new separate fields, with the objective of getting the vehicle make as accurate as possible, and displaying the whole original text in the model field, to allow users a visual display of what was originally in place.

Limited speed zone

Limited speed zone (LSZ) used to be a valid speed limit, and a number of historical crashes have this value. During migration all these have been changed to 50.

Additional surface condition

Currently allows one of ‘wet’, ‘dry’, ‘ice or snow’ as the base road surface condition. In future will also allow multiple ‘additional surface conditions’ as follows:

  • Slick
  • Uneven
  • Under maintenance
  • Fuel
  • Loose material
  • Road edge issues

Road markings

Currently allows one of ‘pedestrian crossing’, ‘raised island’, ‘painted island’, ‘no pass Line’, ‘centre line’, ‘nil’.

In future will allow multiples of:

  • Bus stop
  • Centre line
  • Flush median
  • No passing line
  • No stopping lines/signs
  • Paint island
  • Pedestrian crossing
  • Raised island
  • Turning bay
  • Wide centre lines
  • Nil

Road feature

Currently allows one of bridge, motorway ramp, or railway crossing.

In future, will allow a single value from a larger list, as follows:

  • Bridge
  • Motorway ramp
  • Railway crossing
  • Tunnel
  • Overpass
  • Underpass
  • Speed hump
  • Tram lines
  • Nil

Licence status

The existing licence status field has been rationalised into separate licence type and licence status fields, as follows:

Current licence status values

New license type 

New licence status 

 C Current    Current
 F Full  Full  
 P Provisional    
 R Restricted  Restricted  
 L Learner  Learner  
 M Limited Licence    Limited
 E Expired    Expired
 D Disqualified    Disqualified
 B Forbidden    Forbidden
 W Wrong Class  Wrong Class  
 N Never Licensed  Never Licensed  
 O Overseas  Overseas  
 K Unknown  Unknown  
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