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Conditions - Light

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Light conditions is a STATS19 field which indicates the conditions at the time and location of a crash. it is represented by a MAST dimension.

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In STATS19

Lighting conditions are recorded by combining the prevailing natural lighting conditions when a crash occurred with the presence or otherwise of systems of stree lighting and whether or not they were operational. Hence, raw STATS19 data provides seven possible combinations of lighting conditions:

  • Daylight: street lights present
  • Daylight: no street lighting
  • Daylight: street lighting unknown
  • Darkness: street lights present and lit
  • Darkness: street lights present but unlit
  • Darkness: no street lighting
  • Darkness: street lighting unknown

Darkness is defined as half an hour after sunset to half an hour before sunrise. Daylight means all other times. Scattered or isolated street lamps which are lit are recorded as street lights unlit.

In MAST

Light Conditions is available as a dimension in MAST reports. This dimension contains three alternative hierarchies, representing different possible approaches to grouping the STATS19 data. Users should consider which hierarchy is most appropriate for each report, based on the meaning of the highest levels as defined below.

Crash_Conditions_Light_Daytime hierarchy

Day between half an hour before sunrise and half an hour after sunset

  • Day_LightsPresent
  • Day_NoLights
  • Day_LightsNK

Night between half an hour after sunset and half an hour before sunrise

  • Night_LightsLit
  • Night_LightsUnlit
  • Night_NoLights
  • Night_LightsNK

Crash_Conditions_Light_Lighting hierarchy

This is the default hierarchy which is used when the Conditions - Weather dimension is added as a report category, series or filter without a specific hierarchy being selected.

Present a system of street lighting is present at the crash location

  • Day_LightsPresent
  • Night_LightsLit
  • Night_LightsUnlit

Absent no system of street lighting is present at the crash location

  • Day_NoLights
  • Night_NoLights

Unknown street lighting at crash location unknown

  • Day_LightsNK
  • Night_LightsNK

Crash_Conditions_Light_IsDark hierarchy

Light Driving conditions were illuminated, by natural or artificial means

  • Day_LightsPresent
  • Day_NoLights
  • Night_LightsLit
  • Day_LightsNK

Dark Driving conditions were not illuminated by any means

  • Night_LightsUnlit
  • Night_NoLights

Unknown illumination uncertain

  • Night_LightsNK
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