User’s Guide for Quantifying the Effects of Vehicle Mix on Crash Frequency and Crash Severity (2024)

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N C H R P W e b - O n l y D o c u m e n t 3 9 3 U s e r ’ s G u i d e f o r Q u a n t i f y i n g t h e E f f e c t s o f V e h i c l e M i x o n C r a s h F r e q u e n c y a n d C r a s h S e v e r i t y N a v e e n E l u r u T a n m o y B h o w m i k S h a h r i o r P e r v a z D e w a n A s h r a f u l P a r v e z L a u r e n H o o v e r M o h a m e d A b d e l - A t y U n i v e r s i t y o f C e n t r a l F l o r i d a O r l a n d o , F L K a i W a n g J o h n N . I v a n S h a n s h a n Z h a o M a n m o h a n J o s h i U n i v e r s i t y o f C o n n e c t i c u t S t o r r s M a n s f i e l d , C T C o n d u c t o f R e s e a r c h R e p o r t f o r N C H R P P r o j e c t 2 2 - 4 9 S u b m i t t e d J u n e 2 0 2 3 © 2 0 2 4 b y t h e N a t i o n a l A c a d e m y o f S c i e n c e s . N a t i o n a l A c a d e m i e s o f S c i e n c e s , E n g i n e e r i n g , a n d M e d i c i n e a n d t h e g r a p h i c a l l o g o a r e t r a d e m a r k s o f t h e N a t i o n a l A c a d e m y o f S c i e n c e s . A l l r i g h t s r e s e r v e d . N A T I O N A L C O O P E R A T I V E H I G H W A Y R E S E A R C H P R O G R A M S y s t e m a t i c , w e l l - d e s i g n e d , a n d i m p l e m e n t a b l e r e s e a r c h i s t h e m o s t e f f e c t i v e w a y t o s o l v e m a n y p r o b l e m s f a c i n g s t a t e d e p a r t m e n t s o f t r a n s p o r t a t i o n ( D O T s ) a d m i n i s t r a t o r s a n d e n g i n e e r s . O f t e n , h i g h w a y p r o b l e m s a r e o f l o c a l o r r e g i o n a l i n t e r e s t a n d c a n b e s t b e s t u d i e d b y s t a t e D O T s i n d i v i d u a l l y o r i n c o o p e r a t i o n w i t h t h e i r s t a t e u n i v e r s i t i e s a n d o t h e r s . H o w e v e r , t h e a c c e l e r a t i n g g r o w t h o f h i g h w a y t r a n s p o r t a t i o n r e s u l t s i n i n c r e a s i n g l y c o m p l e x p r o b l e m s o f w i d e i n t e r e s t t o h i g h w a y a u t h o r i t i e s . T h e s e p r o b l e m s a r e b e s t s t u d i e d t h r o u g h a c o o r d i n a t e d p r o g r a m o f c o o p e r a t i v e r e s e a r c h . R e c o g n i z i n g t h i s n e e d , t h e l e a d e r s h i p o f t h e A m e r i c a n A s s o c i a t i o n o f S t a t e H i g h w a y a n d T r a n s p o r t a t i o n O f f i c i a l s ( A A S H T O ) i n 1 9 6 2 i n i t i a t e d a n o b j e c t i v e n a t i o n a l h i g h w a y r e s e a r c h p r o g r a m u s i n g m o d e r n s c i e n t i f i c t e c h n i q u e s — t h e N a t i o n a l C o o p e r a t i v e H i g h w a y R e s e a r c h P r o g r a m ( N C H R P ) . N C H R P i s s u p p o r t e d o n a c o n t i n u i n g b a s i s b y f u n d s f r o m p a r t i c i p a t i n g m e m b e r s t a t e s o f A A S H T O a n d r e c e i v e s t h e f u l l c o o p e r a t i o n a n d s u p p o r t o f t h e F e d e r a l H i g h w a y A d m i n i s t r a t i o n ( F H W A ) , U n i t e d S t a t e s D e p a r t m e n t o f T r a n s p o r t a t i o n , u n d e r A g r e e m e n t N o . 6 9 3 J J 3 1 9 5 0 0 0 3 . C O P Y R I G H T I N F O R M A T I O N A u t h o r s h e r e i n a r e r e s p o n s i b l e f o r t h e a u t h e n t i c i t y o f t h e i r m a t e r i a l s a n d f o r o b t a i n i n g w r i t t e n p e r m i s s i o n s f r o m p u b l i s h e r s o r p e r s o n s w h o o w n t h e c o p y r i g h t t o a n y p r e v i o u s l y p u b l i s h e d o r c o p y r i g h t e d m a t e r i a l u s e d h e r e i n . C o o p e r a t i v e R e s e a r c h P r o g r a m s ( C R P ) g r a n t s p e r m i s s i o n t o r e p r o d u c e m a t e r i a l i n t h i s p u b l i c a t i o n f o r c l a s s r o o m a n d n o t - f o r - p r o f i t p u r p o s e s . P e r m i s s i o n i s g i v e n w i t h t h e u n d e r s t a n d i n g t h a t n o n e o f t h e m a t e r i a l w i l l b e u s e d t o i m p l y T R B , A A S H T O , A P T A , F A A , F H W A , F T A , G H S A , o r N H T S A e n d o r s e m e n t o f a p a r t i c u l a r p r o d u c t , m e t h o d , o r p r a c t i c e . I t i s e x p e c t e d t h a t t h o s e r e p r o d u c i n g t h e m a t e r i a l i n t h i s d o c u m e n t f o r e d u c a t i o n a l a n d n o t - f o r - p r o f i t u s e s w i l l g i v e a p p r o p r i a t e a c k n o w l e d g m e n t o f t h e s o u r c e o f a n y r e p r i n t e d o r r e p r o d u c e d m a t e r i a l . F o r o t h e r u s e s o f t h e m a t e r i a l , r e q u e s t p e r m i s s i o n f r o m C R P . D I S C L A I M E R T h e o p i n i o n s a n d c o n c l u s i o n s e x p r e s s e d o r i m p l i e d i n t h i s r e p o r t a r e t h o s e o f t h e r e s e a r c h e r s w h o p e r f o r m e d t h e r e s e a r c h . T h e y a r e n o t n e c e s s a r i l y t h o s e o f t h e T r a n s p o r t a t i o n R e s e a r c h B o a r d ; t h e N a t i o n a l A c a d e m i e s o f S c i e n c e s , E n g i n e e r i n g , a n d M e d i c i n e ; t h e F H W A ; o r t h e p r o g r a m s p o n s o r s . T h e T r a n s p o r t a t i o n R e s e a r c h B o a r d d o e s n o t d e v e l o p , i s s u e , o r p u b l i s h s t a n d a r d s o r s p e c i f i c a t i o n s . T h e T r a n s p o r t a t i o n R e s e a r c h B o a r d m a n a g e s a p p l i e d r e s e a r c h p r o j e c t s w h i c h p r o v i d e t h e s c i e n t i f i c f o u n d a t i o n t h a t m a y b e u s e d b y T r a n s p o r t a t i o n R e s e a r c h B o a r d s p o n s o r s , i n d u s t r y a s s o c i a t i o n s , o r o t h e r o r g a n i z a t i o n s a s t h e b a s i s f o r r e v i s e d p r a c t i c e s , p r o c e d u r e s , o r s p e c i f i c a t i o n s . T h e T r a n s p o r t a t i o n R e s e a r c h B o a r d , t h e N a t i o n a l A c a d e m i e s , a n d t h e s p o n s o r s o f t h e N a t i o n a l C o o p e r a t i v e H i g h w a y R e s e a r c h P r o g r a m d o n o t e n d o r s e p r o d u c t s o r m a n u f a c t u r e r s . T r a d e o r m a n u f a c t u r e r s ’ n a m e s a p p e a r h e r e i n s o l e l y b e c a u s e t h e y a r e c o n s i d e r e d e s s e n t i a l t o t h e o b j e c t o f t h e r e p o r t . T h e i n f o r m a t i o n c o n t a i n e d i n t h i s d o c u m e n t w a s t a k e n d i r e c t l y f r o m t h e s u b m i s s i o n o f t h e a u t h o r ( s ) . T h i s m a t e r i a l h a s n o t b e e n e d i t e d b y T R B .

e National Academy of Sciences was established in 1863 by an Act of Congress, signed by President Lincoln, as a private, non- governmental institution to advise the nation on issues related to science and technology. Members are elected by their peers for outstanding contributions to research. Dr. Marcia McNutt is president. e National Academy of Engineering was established in 1964 under the charter of the National Academy of Sciences to bring the practices of engineering to advising the nation. Members are elected by their peers for extraordinary contributions to engineering. Dr. John L. Anderson is president. e National Academy of Medicine (formerly the Institute of Medicine) was established in 1970 under the charter of the National Academy of Sciences to advise the nation on medical and health issues. Members are elected by their peers for distinguished contributions to medicine and health. Dr. Victor J. Dzau is president. e three Academies work together as the National Academies of Sciences, Engineering, and Medicine to provide independent, objective analysis and advice to the nation and conduct other activities to solve complex problems and inform public policy decisions. e National Academies also encourage education and research, recognize outstanding contributions to knowledge, and increase public understanding in matters of science, engineering, and medicine. Learn more about the National Academies of Sciences, Engineering, and Medicine at www.nationalacademies.org. e Transportation Research Board is one of seven major program divisions of the National Academies of Sciences, Engineering, and Medicine. e mission of the Transportation Research Board is to mobilize expertise, experience, and knowledge to anticipate and solve complex transportation-related challenges. e Board’s varied activities annually engage about 8,500 engineers, scientists, and other transportation researchers and practitioners from the public and private sectors and academia, all of whom contribute their expertise in the public interest. e program is supported by state transportation departments, federal agencies including the component administrations of the U.S. Department of Transportation, and other organizations and individuals interested in the development of transportation. Learn more about the Transportation Research Board at www.TRB.org.

C O O P E R A T I V E R E S E A R C H P R O G R A M S CRP STAFF FOR NCHRP WEB-ONLY DOCUMENT 393 Waseem Dekelbab, Deputy Director, Cooperative Research Programs, and Manager, National Cooperative Highway Research Program Camille Crichton-Sumners, Senior Program Officer Mazen Alsharif, Senior Program Assistant Natalie Barnes, Director of Publications Heather DiAngelis, Associate Director of Publications Jennifer J. Weeks, Publishing Projects Manager NCHRP PROJECT 22-49 PANEL Field of Design—Area of Vehicle Barrier Systems Randy E. Bradley, Florida DOT, Tallahassee, FL (Chair) William Gordon Paille, BSC Group, Inc., Boston, MA Jeffrey A. Pulver, Maine DOT, Jefferson, ME Karla Cristina Rodrigues-Silva, University of Florida, Lake Mary, FL Ida Van Schalkwyk, Washington State DOT, Olympia, WA Jonathan S. Wood, Iowa State University, Ames, IA Carol H. Tan, FHWA Liaison Kelly K. Hardy, AASHTO Liaison

iv TABLE OF CONTENTS LIST OF TABLES .......................................................................................................................... v LIST OF FIGURES ....................................................................................................................... vi 1 PROJECT BACKGROUND ................................................................................................... 1 1.1 Development of the Statistical Models ......................................................................... 1 1.2 Development of the Excel Spreadsheet Tools .............................................................. 3 2 22-49 SPREADSHEET TOOL WITHOUT CALIBRATION ................................................ 5 2.1 Opening the Tool .......................................................................................................... 5 2.2 Import Data ................................................................................................................... 6 2.3 Selection of Facility .................................................................................................... 11 2.4 Estimation of Prediction ............................................................................................. 14 3 22-49 SPREADSHEET TOOL WITH CALIBRATION ...................................................... 18 3.1 Opening the Tool ........................................................................................................ 18 3.2 Import Data ................................................................................................................. 18 3.3 Selection of Facility .................................................................................................... 21 3.4 Estimation of Prediction ............................................................................................. 22 3.5 Calibration .................................................................................................................. 24 3.6 Development of Cure Plot .......................................................................................... 26 4 22-49 DATA INPUT AND PREDICTION TOOL ............................................................... 28 4.1 Opening the Tool ........................................................................................................ 28 4.2 Segment Data Input and Prediction ............................................................................ 28 4.3 Intersection Data Input and Prediction ....................................................................... 33 NCHRP Web-Only Document 393 contains the Conduct of Research Report for NCHRP Project 22-49 and accompanies NCHRP Research Report 1103: The Effect of Vehicle Mix on Crash Frequency and Crash Severity. Readers can read or purchase NCHRP Research Report 1103 on the National Academies Press website (nap.nationalacademies.org).

v LIST OF TABLES Table 1.1 Description of the Facilities ............................................................................................ 2 Table 1.2 Recommended Model for Each Facility ......................................................................... 3 Table 2.1 Description of the Variables ........................................................................................... 7

vi LIST OF FIGURES Figure 2.1 Unblocking the Tool ...................................................................................................... 5 Figure 2.2 Enabling the Content ..................................................................................................... 6 Figure 2.3 Data Import (Spreadsheet Tool without Calibration) .................................................... 8 Figure 2.4 Workbook for RA4LUD with “data” Tab (Spreadsheet Tool without Calibration) ..... 9 Figure 2.5 Variable List View (Spreadsheet Tool without Calibration) ....................................... 10 Figure 2.6 ImportedData Tab (Spreadsheet Tool without Calibration) ........................................ 11 Figure 2.7 Facility Selection (Spreadsheet Tool without Calibration) ......................................... 12 Figure 2.8 Facility Description (Spreadsheet Tool without Calibration) ..................................... 13 Figure 2.9 Defined SPF Tab (Spreadsheet Tool without Calibration) .......................................... 14 Figure 2.10 Estimating Prediction (Spreadsheet Tool without Calibration) ................................. 15 Figure 2.11 Options to Use User-Defined Calibration Factors (Spreadsheet Tool without Calibration) ................................................................................................................................... 16 Figure 2.12 Estimated Prediction Results of RA4LUD Facility (Spreadsheet Tool without Calibration) ................................................................................................................................... 17 Figure 3.1 Data Import (Spreadsheet Tool with Calibration) ....................................................... 18 Figure 3.2 Workbook for RA4LUD Facility with “data” Tab (Spreadsheet Tool with Calibration) ....................................................................................................................................................... 19 Figure 3.3 Variable List (Spreadsheet Tool with Calibration) ..................................................... 20 Figure 3.4 ImportedData Tab (Spreadsheet Tool with Calibration) ............................................. 20 Figure 3.5 Facility Selection (Spreadsheet Tool with Calibration) .............................................. 21 Figure 3.6 Facility Description (Spreadsheet Tool with Calibration) ........................................... 22 Figure 3.7 Defined SPF Tab (Spreadsheet Tool with Calibration) ............................................... 22 Figure 3.8 Selection of Output (Spreadsheet Tool with Calibration) ........................................... 23 Figure 3.9 Estimated Prediction Results of RA4LUD Facility (Spreadsheet Tool with Calibration) ....................................................................................................................................................... 23 Figure 3.10 Estimated Calibrated Prediction Results of RA4LUD Facility ................................. 25 Figure 3.11 Calibration Factors for RA4LUD Facility ................................................................. 25 Figure 3.12 Cure Plots Tab ........................................................................................................... 26 Figure 3.13 Residuals and Confidence Limits of the Cure Plots for RA4LUD Facility .............. 27 Figure 4.1 “Segment Input” Tab ................................................................................................... 29 Figure 4.2 Selection of Segment Facility Type ............................................................................ 29 Figure 4.3 Generating Segment Dataset and Prediction ............................................................... 30 Figure 4.4 Segment Data Input Error ............................................................................................ 31 Figure 4.5 “Segment Output” Tab Showing Input Data ............................................................... 31 Figure 4.6 “Segment Output” Tab Showing Predictions .............................................................. 32 Figure 4.7 Clearing the Segment Output ...................................................................................... 33 Figure 4.8 “Intersection Input” Tab .............................................................................................. 34 Figure 4.9 Selection of Intersection Facility Type ........................................................................ 34 Figure 4.10 Generating Intersection Dataset and Prediction ........................................................ 35 Figure 4.11 Intersection Data Input Error ..................................................................................... 35 Figure 4.12 “Intersection Output” Tab Showing Data .................................................................. 36 Figure 4.13 “Intersection Output” Tab Showing Predictions ....................................................... 36 Figure 4.14 Clearing the Intersection Input Data .......................................................................... 37