Types of Safety Data

• Crash• Roadway Inventory• Vehicle Registration• Driver Licensing• Citation/Adjudication• Injury Surveillance/EMS

Need to be linked …are they? Can they be?

Why collect/maintain safety data?

• Khisty says:

• Is that all? – Better understanding of operational problems– Accurate diagnosis of crash problems– Develop remedial measures– Evaluate the effectiveness of road safety programs

Who uses crash data?– Road safety engineers

• Develop remedial measures

– Police• Charging a person at fault in

crash• Enforcement activities

– Location of speed cameras– Breath testing stations

– Insurers• Seeking facts before settling

claims

– Lawyers• Compensation for injuries

– Road safety educators• To ensure that their efforts

well targeted

– Safety administrators• Report statistical information

on road crashes

– Researchers• Access good reliable database

– Vehicle manufacturers• Assess the safety of their

products

Importance of good data (Video “L”)

Crash Data (and some road/traffic data)

• Usually collected by police– Sometimes drivers – when? thoughts?

• Forms (paper and electronic)• Usually includes info on

– Location, time, roadway and envir. conditions, type and # of vehicles, sketch, severity*

• Supplements for commercial vehicles, fatalities, other …

And, for Commercial Motor Carriers …• Identifying the appropriate Commercial Motor Carrier• Determining Reportable Crashes• Identifying Vehicle Configuration and Cargo Body Type• Determining Sequence of Events• Recording Hazardous Materials• Recording proper CDL

What is reportable?• In most US states, the five point scale often referred to as

KABCO– K person with fatal injury– A person with incapacitating injury– B person with non-incapacitating evident injury– C person with possible injury– O no injury (property damage only)

• Some countries report injury crashes only• Some states do not differentiate between injury types

– Implication?

• Some crashes are not reported … why?• Many states use a reporting “threshold”

– May vary even within states … implication?

Location• An early computerized “spot” map (from Khisty)

Can you “spot” the problems?

Other examples

Crashes by Time of Day

Crashes by Age

Crashes by Road Surface Conditions

Drug and Alcohol Related Crashes

GIS-ALAS: Corridor Crash Frequency (stacked)

Injury Frequency by Severity

Injury Frequency by Severity

Collision Diagrams

Road Data (not from crash forms)

• Traffic– Turning movement (boards)– Short term (tubes)– Long term counts (ATRs)

• Geometry & features– Manual observation/measurements– Video/sensor vans

Supplementary data sources (Ogden)

• While police crash report is the basic source of crash data, there are some other sources which may be useful and applicable in certain circumstances– Local knowledge

• Local government staff• Emergency service personnel• Local safety groups• Local businesses

– Interview of road users• People involved in a crash at a site of interest, which are source of useful

information for traffic officials in development of countermeasures– In-depth studies of particular group of crashes

• Single vehicle fatal crashes, to gain better understanding of the nature of those crashes

Supplementary data sources (continued)

– Traffic conflict surveys • May be used when the collection of crash data is not practical or period

of evaluation is too short to collect sufficient samples– Field observation– Video recording of conflicts

• Information gained in this way is valuable in – getting a sound understanding of the traffic operation– Find interactions between traffic streams at the site

• As a proxy measure of safety– Assumption must be made about relationship between proxy measure

(conflict) and crash rates

– Site investigations are necessary component of a countermeasure development program