1 Element 1: The Systemic Safety Project Selection Process Element 1: 4-Step Project Selection Process

Objective Identify risk factors commonly associated with target crash type(s) experienced across a system. Suggest a focus on severe crashes (fatal + serious injury) – Consistent with national safety practices – May minimize effort and needed resources 2 Element 1, Step 1: Identify Target Crash Types & Risk Factors

Outcome Gain an understanding of the systemic program’s focus – Type of Crash – Facility Type (i.e., location type) – Risk Factors 3 Element 1, Step 1: Identify Target Crash Types & Risk Factors

Recommended Minimum Data Crashes by system (state and local) Crash type (road departure, right angle, head-on rear end, turning, etc.) Facility type (freeway, expressway and conventional) Physical crash location description (urban/rural, intersection/segment, tangent/curve, topography, etc.) Description of location (topography, intersection elements, segment elements) 4 Element 1, Step 1: Identify Target Crash Types & Risk Factors

Potentially Useful Data (i.e., Risk Factors) Traffic volumes Some Roadway Features – Number of lanes – Shoulder type/width – Road edge features/quality – Number/type of access – Radius of horizontal curves – Density of horizontal curves – Speed limit – Medians Some Intersection Features – Number of approaches – Skew – Proximity to horizontal/vertical curves – Number of approach lanes – Signal timing – Proximity to railroad crossing – Traffic control devices – Presence of street lighting – Presence of commercial developments 5 Element 1, Step 1: Identify Target Crash Types & Risk Factors

Element 1: Step 1 6 Element 1, Step 1: Identify Target Crash Types & Risk Factors

Element 1: Step 1, Task 1 Select Focus Crash Type(s) Purpose: Identify the greatest potential to reduce fatalities and severe injuries. Suggestion: Identify crash type(s) representing the greatest number of severe crashes across system. Element 1: Step 1, Task 1 7

Element 1: Step 1, Task 1 Select Focus Crash Type(s) Why is it important to select a focus crash type(s)? There is no single countermeasure that is effective at addressing all crash types. Identifying a focus crash type(s) will help narrow down the list of countermeasures. 8 Q: A: Element 1: Step 1, Task 1

Element 1: Step 1, Task 1 Select Focus Crash Type(s) Resources: State or regional SHSP – AASHTO’s 22 Emphasis Areas Roadway Departure or Intersection Safety Implementation Plans Other applicable safety plans Statewide and regional crash data Element 1: Step 1, Task 1 9

Element 1: Step 1, Task 1 Select Focus Crash Type(s) Process: 1.Reference emphasis areas defined in approved safety plans (State SHSP). 2.Stratify crash data into emphasis areas. 3.Select focus crash type(s): – Emphasis areas with highest frequency crashes – Priority order of emphasis areas in plans – Agency preferences Element 1: Step 1, Task 1 10

Statewide Data by Safety Emphasis Area 11 Element 1: Step 1, Task 1 Illustration: Jurisdiction can make a difference

Region Data by Safety Emphasis Area 12 Element 1: Step 1, Task 1 Illustration: Consider impact of geography & topography

Element 1: Step 1, Task 1 Select Focus Crash Type(s) Possible Challenges for Thurston County: 1.Relatively few severe crashes?…difficult to identify focus crash type(s) 2.Urban and rural areas have distinctly different crash patterns? Element 1: Step 1, Task 1 13

Element 1: Step 1, Task 2 Select Focus Facilities Purpose: Determine locations on roadway network where focus crashes occur most frequently. Element 1: Step 1, Task 2 14

Element 1: Step 1, Task 2 Select Focus Facilities Why is it important to select focus facilities? There is no single countermeasure that is appropriate for all situations. Identifying a focus facility type will help narrow down the list of countermeasures. 15 Q: A: Element 1: Step 1, Task 2

Element 1: Step 1, Task 2 Select Focus Facilities Resources: Roadway Departure or Intersection Safety Implementation Plans Statewide and regional crash data Process: 1.Develop crash tree diagram. 2.Utilize diagram to identify and select focus facilities. Element 1: Step 1, Task 2 16

Greater Minnesota Crash Tree Diagram 17 5 Year Crashes 156,182 4,902 5 Year Crashes 156,182 4,902 State System 70,808 – 45% 2,000 – 41% State System 70,808 – 45% 2,000 – 41% CSAH/CR 36,716 – 24% 1,963 – 40% CSAH/CR 36,716 – 24% 1,963 – 40% Rural 22,630 – 62% 1,626 – 83% Rural 22,630 – 62% 1,626 – 83% Urban 14,086 – 38% 337 – 17% Urban 14,086 – 38% 337 – 17% All Way Stop 445 – 6% 5 – 3% All Way Stop 445 – 6% 5 – 3% Run off Road 7,891 – 67% 675 – 65% Run off Road 7,891 – 67% 675 – 65% On Curve 3,222 – 40% 339 – 50% On Curve 3,222 – 40% 339 – 50% Example All – % Severe – % Example All – % Severe – % Right Angle – 1,268 (47%), 37 (86%) “Other” – 252 (9%), 9 (21%) Left Turn – 268 (10%), 4 (9%) Rear End – 333 (12%), 3 (7%) Right Angle – 1,268 (47%), 37 (86%) “Other” – 252 (9%), 9 (21%) Left Turn – 268 (10%), 4 (9%) Rear End – 333 (12%), 3 (7%) Thru-Stop 2,697 – 37% 65 – 45% Thru-Stop 2,697 – 37% 65 – 45% Right Angle – 633 (27%), 15 (47%) Rear End – 799 (35%), 5 (16%) Left Turn – 375 (16%), 5 (16%) Head On – 100 (4%), 4 (13%) Right Angle – 633 (27%), 15 (47%) Rear End – 799 (35%), 5 (16%) Left Turn – 375 (16%), 5 (16%) Head On – 100 (4%), 4 (13%) Signalized 2,308 – 31% 32 – 22% Signalized 2,308 – 31% 32 – 22% Inters-Related 5,487 – 29% 463 – 30% Inters-Related 5,487 – 29% 463 – 30% Source: MnCMAT Crash Data, Severe is fatal and serious injury crashes (K+A). City, Twnshp, Other 48,658 – 31% 939 – 19% City, Twnshp, Other 48,658 – 31% 939 – 19% Inters-Related 7,332 – 52% 145 – 43% Inters-Related 7,332 – 52% 145 – 43% Not Inters-Related 5,177 – 37% 175 – 52% Not Inters-Related 5,177 – 37% 175 – 52% Run Off Road – 1,202 (23%), 69 (39%) Head On – 366 (7%), 27 (15%) “Other” – 540 (10%), 25 (14%) Rear End – 1,336 (26%), 17 (10%) Run Off Road – 1,202 (23%), 69 (39%) Head On – 366 (7%), 27 (15%) “Other” – 540 (10%), 25 (14%) Rear End – 1,336 (26%), 17 (10%) Animal 4,009 – 18% 60 – 4% Animal 4,009 – 18% 60 – 4% Not Inters-Related 11,849 – 64% 1,042 –66% Not Inters-Related 11,849 – 64% 1,042 –66% Head On, SS Opp. 751 – 6% 132 – 13% Head On, SS Opp. 751 – 6% 132 – 13% On Curve 247 – 33% 46 – 35% On Curve 247 – 33% 46 – 35% Unknown/Other 1,577 – 11% 17 – 5% Unknown/Other 1,577 – 11% 17 – 5% Unknown/Other 1,276 – 7% 61 – 4% Unknown/Other 1,276 – 7% 61 – 4% Other/Unknown 1,881 – 26% 43 – 30% Other/Unknown 1,881 – 26% 43 – 30% Right Angle – 849 (34%), 122 (56%) “Other” – 464 (18%), 33 (15%) Run Off Road – 342 (14%), 21 (10%) Left Turn – 184 (7%), 10 (5%) Right Angle – 849 (34%), 122 (56%) “Other” – 464 (18%), 33 (15%) Run Off Road – 342 (14%), 21 (10%) Left Turn – 184 (7%), 10 (5%) Thru-Stop 2,511 – 46% 216 – 47% Thru-Stop 2,511 – 46% 216 – 47% Run Off Road – 999 (38%), 95 (42%) Right Angle – 268 (10%), 39 (17%) “Other” – 303 (12%), 29 (13%) Head On – 112 (4%), 21 (9%) Run Off Road – 999 (38%), 95 (42%) Right Angle – 268 (10%), 39 (17%) “Other” – 303 (12%), 29 (13%) Head On – 112 (4%), 21 (9%) Other/Unknown 2,600 – 47% 228 – 49% Other/Unknown 2,600 – 47% 228 – 49% Not Animal 18,616 – 82% 1,566 – 96% Not Animal 18,616 – 82% 1,566 – 96% All Way Stop 164 – 3% 15 – 3% All Way Stop 164 – 3% 15 – 3% Signalized 209 – 4% 4 – 1% Signalized 209 – 4% 4 – 1% -Region’s 1, 2, 3, 4, 6, 7, and 8 – NO Metro Element 1: Step 1, Task 2

Element 1: Step 1, Task 2 Select Focus Facilities Suggest Minimum Crash Tree Combinations: – Location (urban / rural) – Ownership (state and local) – Segment or intersection – Segment type (freeway, multilane, two-lane, one-way) – Intersection control type (signal, stop, yield) Additional Crash Tree Combinations: – Tangent or curve – High- or low-speed – Presence of street lighting – District or regions 18 Element 1: Step 1, Task 2

Element 1: Step 1, Task 3 Identify and Evaluate Risk Factors Purpose: Document the most common characteristics of the crash locations to further define the facility types selected from the crash tree in Step 1, Task 2. Element 1: Step 1, Task 3 19

Element 1: Step 1, Task 3 Identify and Evaluate Risk Factors Why are risk factors needed? Risk factors help differentiate which locations may have the greatest potential for a future focus crash type. These locations become the priority for where to deploy countermeasures. 20 Q: A: Element 1: Step 1, Task 3

Element 1: Step 1, Task 3 Identify and Evaluate Risk Factors Resources: Crash data at statewide and regional levels Road and intersection data Highway Safety Manual FHWA’s Crash Modification Factor Clearinghouse Published research documenting the effectiveness of strategies Element 1: Step 1, Task 3 21

Element 1: Step 1, Task 3 Identify and Evaluate Risk Factors Process: 1.Determine potential risk factors considering: – Ability to indicate greater potential for a future severe focus crash type – Availability of data element in existing databases or the ability to quickly gather data if not already available – Quality of data element if contained in existing databases – Applicability of data element to focus crash type and facility type Element 1: Step 1, Task 3 22

Element 1: Step 1, Task 3 Identify and Evaluate Risk Factors Process: 2. Evaluate potential risk factors for a relationship to future crash potential: – Formal statistical analysis to determine if risk factor associated with crash frequency – Compare proportions…proportion of all locations with the characteristic versus proportion severe crash locations with (descriptive statistics) – Review published research to identify Crash Modification Factors 3. Select risk factors. Element 1: Step 1, Task 3 23

Evaluation of Segment Traffic Volume as Potential Risk Factor Element 1: Step 1, Task 3 24

Evaluation of Curve Radius as Potential Risk Factor 25 Element 1: Step 1, Task 3

Evaluation of Access Density as Potential Risk Factor Element 1: Step 1, Task 3 26