Diagnosis 1 Diagnosis Step 1 Safety data review

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Diagnosis 1

Diagnosis 1

Diagnosis Step 1: Safety data review Step 2: Access supporting documentation Step 3: Access

Diagnosis Step 1: Safety data review Step 2: Access supporting documentation Step 3: Access field condition 2

Step 1: Safety Data Review 1. Descriptive crash statistics • Crash identifiers • Crash

Step 1: Safety Data Review 1. Descriptive crash statistics • Crash identifiers • Crash type • Crash severity • Sequence of events • Contributing Circumstances 2. Crash locations: Collision and condition diagram 3

Collision Diagram 4

Collision Diagram 4

Condition Diagram 5

Condition Diagram 5

Step 2: Access supporting documents • • Current traffic volume As-built construction plans Relevant

Step 2: Access supporting documents • • Current traffic volume As-built construction plans Relevant design criteria Maintenance log Recent traffic studies Land use mapping Roadway improvement plans etc. 6

Step 3: Access field conditions • • Roadway and roadside characteristics Traffic conditions Traveler

Step 3: Access field conditions • • Roadway and roadside characteristics Traffic conditions Traveler behavior Roadway consistency Land uses Weather conditions Evidence of problems 7

Example Problem 8

Example Problem 8

Information needed for each site • A set of pie charts summarizing the crash

Information needed for each site • A set of pie charts summarizing the crash data. • Collision diagram • Condition diagram • A written assessment and summary of the site diagnosis. 9

Detail crash data for pie charts 10

Detail crash data for pie charts 10

Sample Assessment Summary 11

Sample Assessment Summary 11

Select Countermeasures 12

Select Countermeasures 12

Identifying contributing factors for segments • • Vehicle rollover Fixed object Nighttime Wet pavement

Identifying contributing factors for segments • • Vehicle rollover Fixed object Nighttime Wet pavement Head-on Run-off Bridges Etc. 13

Identifying potential countermeasures for angle crashes • Convert stop-controlled intersection to modern roundabout •

Identifying potential countermeasures for angle crashes • Convert stop-controlled intersection to modern roundabout • Convert two-way stop controlled to all-way • Provide exclusive left turn one or more lanes. 14

Find CMF and costs for each potential countermeasures Source: 1. http: //www. cmfclearinghouse. org/

Find CMF and costs for each potential countermeasures Source: 1. http: //www. cmfclearinghouse. org/ index. cfm 15

Economic appraisal 16

Economic appraisal 16

Economic Appraisal Process 17

Economic Appraisal Process 17

Data Needs 18

Data Needs 18

In-class A countermeasure is estimated to reduce the expected average crash frequency of fatal/injury

In-class A countermeasure is estimated to reduce the expected average crash frequency of fatal/injury by 5 crashes per year and the number of PDO crashes by 11 per year over the service year of the project. What is the annual monetary benefit associated with the crash reduction? Assume, discount rate 4%, and service year 5 years. 19

Societal Crash Cost 20

Societal Crash Cost 20

Prioritize Projects and Safety Effectiveness 21

Prioritize Projects and Safety Effectiveness 21

In Lab Economic appraisal analysis for intersection 2 considering traffic growth, discount rate, benefits,

In Lab Economic appraisal analysis for intersection 2 considering traffic growth, discount rate, benefits, and costs for 10 years of service life. - Learn optimization in managing safety 22