Crash Analysis Reporting System (CARS) & How to Prepare a Black Spot NominationAdam Hazebroek – A / Road Safety Investigator (MRWA)

Where to start?• Go to Main Roads website

• Log in and select Reporting Centre

• Select Crash

• Select Analysis (CARS)

• Select Crash Analysis Reporting System

• Refer to the user manual if needed (circled in red)• Select a crash location• There are lists available of locations which have been

pre-qualified for Black Spot funding

• Selecting a location from these lists will improve the likelihood of receiving funding as they have crash volumes that meet the Black Spot crash criteria

• Select either State Roads or Local Roads, depending on whether you represent Local Government or Main Roads

• Select either Australian Government Black Spot Program or State Black Spot Program

• Select the LG or Region name for the relevant area

• For intersections, you will see a list of locations which meet the crash criteria for Black Spot funding.

• For road sections, you will see a list of roads with sections that meet the crash criteria. You will first need to select a road:

• It will then display a list of road sections that meet the criteria.

• For Locus Distance, in most cases select the default “No Locus”

• You may apply a locus when analysing approaches to intersection

• CARS will then generate reports including a Crash Factor Matrix and a Crash Pattern Report

• This is an example of a Crash Factor Matrix

• It displays crash types in the left column and crash characteristics in the top row

• “Casualty crashes” includes all Fatal, Hospital and Medical crashes

• You will also need to run a Detailed Crash History report• Click on Crash Analysis near the top left of your screen

• You should then run the report on the same location that you selected from the pre-qualified list

• Then select Reports and Detailed Crash History

• For road sections, enter the same SLK points as the section from the pre-qualified list

• For intersections, enter one road name and then select the intersecting road from the list

• For Report Parameters retain the default values– or select Fatal, Hospital and Medical if considering

casualty crashes only

• For the Output Format, select CSV File Extract

• The report provides detailed crash characteristics such as SLK, crash severity, site conditions and GPS co-ordinates

• For multiple vehicle crashes, there is a row for each vehicle

• For most tasks, you need to remove the secondary vehicles from the report

• Locate column Y (Unit) on the CSV file, apply a filter, untick the “Target” vehicle and retain the “Colliding” vehicle

• Map the crash locations

• There are two methods to do this:

- manually search for crash locations and mark them on a map; or

- upload the GPS co-ordinates from the CSV file into a GIS mapping system and plot them onto a map

• You can use different symbology for certain characteristics, such as crash severity

• In this example, hospital crashes are green circles and medical crashes are black triangles

• Review the map and crash reports in conjunction with visual aids such as aerial photographs and street view

• Check if the selected location appears suitable for potential treatments - you may need to alter the scope

• For example, if the location is 0.00 – 1.00 SLK and a possible treatment is installing a median, it may need to terminate at 1.20 SLK

• This would require you to increase the scope

• Alternatively, a proposed treatment may not provide reductions to all crashes at the selected location

• In this case you may need to reduce the scope

• When altering the scope, you will need to – run crash reports again on the altered scope– update the crash map– check the selected area still meets the Black Spot crash

criteria

• Create a “Stick Diagram” on the map• For each crash location, annotate the crash characteristics:

- RUM code- severity- surface

condition (wet / dry)

- light condition (day / night)

- date & time- vehicle type

• For intersections, a Collision Diagram is available in CARS• Collision Diagrams are indicative only• They do not provide a detailed understanding of crashes eg.

crash severities and site conditions

• A “Stick Diagram” is needed to understand the crash problems• An example is provided below:

• Complete a crash summary• Group crashes by crash type • Identify crash severity, travel directions and site conditions• An example is provided on the Crash Analysis Form in the

“How to Prepare a Black Spot Nomination” document

• Refer to the stick diagram and Detailed Crash History report to complete the details.

• Start by selecting the crash type resulting in the highest number of casualty crashes– eg. 17 crashes involving vehicles failing to give way

• Identify the group of this crash type which is the biggest problem eg. highest severity crashes, or highest volume of crashes

• Start your summary by stating the movement or direction of travel first– eg. 13 crashes involving northbound vehicles on

North St failing to give way to westbound vehicles on West St

• Next, state the site conditions– eg. all occurring in the dry, 8 occurring during times

of darkness• Conclude by stating the resulting severities

– eg. 1 resulting in a fatality, 2 resulting in hospital severity, 5 resulting in medical severity and 5 resulting in major property damage

• Repeat this process for each crash type until you have summarised all of the crashes

• Complete the Predominant Crashes section of the form• Identify the prominent crash patterns from the crash summary• A prominent crash pattern may include:

– specific traffic movements resulting in high severity crashes and/or high volume of crashes

eg. 13 northbound vehicles on North Street failing to give way to westbound vehicles resulting in 1 fatality, 2 hospital severities and 5 medical severities

• Another example of a prominent crash pattern may include:– crashes influenced by site conditions resulting in a

significant volume or severity of crashes eg. 12 intersection crashes occurring in darkness, 10 involving vehicles failing to give way and 2 rear end crashes

• To summarise up to this point:– identify a crash location– run crash reports– map the crashes– conduct a broad crash analysiswith combined reference to:

• crash reports• your crash map• aerial photography

• If there is a crash pattern and potential to provide treatments, conduct a detailed crash analysis by completing the following steps:– create a stick diagram– complete a crash summary on the Crash Analysis Form

• Conduct a site inspection• Identify physical features at the site that may have contributed

to crashes• Appendix C in the “How to Prepare a Black Spot Nomination”

provides a list of possible contributing factors for different crash types

• Select an appropriate cost-effective crash treatment• Refer to the Crash Reduction Factors (CRF) spreadsheets

under the Countermeasures tab in CARS (circled in red)

• The Crash Reduction Factors (CRF) spreadsheets show the expected percentage reduction (or increase) in casualty crashes for different crash types– the columns display the crash types (red circle)– the rows display the available treatments (blue circle)– the cells display the expected reduction (green circle)

• This example indicates installing a “Continuous raised median on existing road” would reduce RUM1 crashes by 50%.

• The Austroads Road Safety Engineering Toolkit is also a useful resource - you can enter a crash type and it provides a list of possible treatments

• If unable to identify appropriate treatments, consider alternatives:– alter the scope of the crash investigation area

• this may introduce additional crashes that provide increased justification or alternative options

• If still unable to identify an appropriate treatment, consider treating alternate crash locations

• When a suitable treatment is identified, check that it fits the defined scope and alter if required– whenever altering the scope, check that it still meets

the crash criteria

• Check for any changes to the road within the 5 year crash period which may influence the crash history– if treatments have been applied, these locations should

not be nominated for Black Spot– continue to monitor them instead

• The next step is to perform a BCR calculation• Before calculating a BCR ensure understanding of the

following:– predominant crash types– physical features at the site contributing to crash

causation and/or severity– how you expect your selected treatment to reduce crashes– project scope is correct and meets the crash criteria

• The selected treatment must effectively treat the predominant crash types for your application to be successful

• To perform a BCR calculation, select your location in CARS and run the crash report

• Select the Countermeasures tab

• For Crash Cost Saving Category select:– “Nature – Open Road” for 80 km/h or greater – “Nature – Built Up” for 70 km/h or less

• Retain default values for Year and Discount Rate fields• Complete these steps prior to selecting countermeasures

– changing them afterwards can affect the BCR calculation

• To enter a countermeasure, click on the Add Countermeasure button (red circle)

• Select a countermeasure from the drop-down list (blue circle)• Select the applicable approach legs from the drop-down list

(green circle)

• Update capital expenditure and operating expenditure with proposed project costs

• Complete these steps for any additional countermeasures• Ensure the BCR value is correctly calculated (press the

Enter key after the last value entered)• Check the BCR meets the Black Spot criteria

• If your proposed treatment is not in the countermeasures list, you will need to calculate the BCR manually

• To do this, you will need to refer to the Crash Costs table (circled in red)

• The on-line Road Safety Engineering Course provides instruction on how to manually calculate BCR’s

• If you have an appropriate treatment and a BCR that meets the criteria, you can complete the Black Spot Nomination form

• Check that the requirements under “Nomination Form Submission” in the “How to Prepare a Black Spot Nomination” document are satisfied

• If unable to find a crash location for treatment, or cannot obtain a BCR to meet the criteria, refer to “Potentially Hazardous Locations”

Questions?

Adam HazebroekA / Road Safety InvestigatorPlanning and Technical Servicesadam.hazebroek@mainroads.wa.gov.au08 9323 4633