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The 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. The 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. C. D. Mote, Jr., is president. The 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. The 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. The 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.national-academies.org. The Transportation Research Board is one of seven major programs of the National Academies of Sciences, Engineering, and Medicine. The mission of the Transportation Research Board is to increase the benefits that transportation contributes to society by providing leadership in transportation innovation and progress through research and information exchange, conducted within a setting that is objective, interdisciplinary, and multimodal. The Boardâs varied committees, task forces, and panels annually engage about 7,000 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. The 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.
NCHRP Project 17-61 i TABLE OF CONTENTS LIST OF FIGURES ..................................................................................................................... iii LIST OF TABLES ....................................................................................................................... iv SUMMARY ................................................................................................................................... 1 CHAPTER 1 BACKGROUND .................................................................................................... 3 Introduction ................................................................................................................................... 3 Project Objectives ......................................................................................................................... 4 Contents of this Report ................................................................................................................. 4 CHAPTER 2 CAUSAL ASSESSMENTS OF WORK ZONE CRASHES .............................. 6 Overview ........................................................................................................................................ 6 Analysis of VDOT RNS Crash Data ........................................................................................... 6 Methodology ............................................................................................................................................................ 7 Results of Analysis..................................................................................................................................................... 8 Rearâend Crashes ................................................................................................................................................. 9 Angle Crashes ..................................................................................................................................................... 10 Sideswipe â Same Direction ................................................................................................................................ 11 Fixed Object RunâOffâRoad Crashes ................................................................................................................... 12 Collisions with Work Zone Vehicles ................................................................................................................... 12 Summary of Findings of VDOT Crash Analysis ........................................................................................................ 13 Analyses of the NMVCCS and LTCCS Databases .................................................................. 14 NMVCCS Analysis .................................................................................................................................................... 15 Methodology ...................................................................................................................................................... 15 Results of Analysis .............................................................................................................................................. 15 LTCCS Analysis ......................................................................................................................................................... 22 Methodology ...................................................................................................................................................... 22 Results of Analysis .............................................................................................................................................. 24 Summary of Findings from the NMVCCS and LTCCS Analyses ................................................................................ 31 New Insights Gained Through the Analyses ............................................................................ 33 CHAPTER 3 EFFECTS OF QUEUING AND CRASH COUNTERMEASURES AT INTERSTATE WORK ZONE LANE CLOSURES ................................................................ 35 Overview ...................................................................................................................................... 35
NCHRP Project 17-61 ii Methodology ................................................................................................................................ 36 Description of the Study Corridor ........................................................................................................................... 36 Description of the Queue Warning Crash Countermeasures ................................................................................. 36 Description of the Analysis Methodology ............................................................................................................... 38 Determining When Traffic Queues Were Present ............................................................................................. 38 Safety Analysis Methodology ............................................................................................................................. 40 Results .......................................................................................................................................... 41 Discussion..................................................................................................................................... 43 CHAPTER 4 STATISTICAL MODELING OF WORK ZONE FEATURES UPON CRASHES .................................................................................................................................... 45 Overview ...................................................................................................................................... 45 Database Development ............................................................................................................... 45 Statistical Analysis Methodology ............................................................................................... 51 Modeling Results ......................................................................................................................... 53 SUMMARY AND RECOMMENDATIONS ............................................................................ 62 Summary ...................................................................................................................................... 62 Research Recommendations ...................................................................................................... 63 REFERENCES ............................................................................................................................ 65 ABBREVIATIONS AND ACRONYMS ................................................................................... 67Â
NCHRP Project 17-61 iii LIST OF FIGURES Figure 1. Illustration of dissecting work zone crashes into causal factors. .................................................. 7 Figure 2. Initial classification of NMVCCS crashes in or near work zones on freeway/interstate roadways. ................................................................................................................ 16 Figure 3. NMVCCS crashes in or near work zones on freeway/interstate roadways based on direct relation to the work zone. ........................................................................................................... 18 Figure 4. Initial classification of NMVCCS crashes in or near work zones on non-freeway/interstate roadways. ......................................................................................................... 21 Figure 5. NMVCCS crashes in or near work zones on non-freeway roadways based on potential influence of the work zone. ................................................................................................... 23 Figure 6. Initial classification of LTCCS crashes in or near work zones on freeway/interstate roadways. ................................................................................................................ 25 Figure 7. LTCCS crashes in or near work zones on freeways/interstates based on direct relation to the work zone. ........................................................................................................... 27 Figure 8. Initial classification of LTCCS crashes in or near work zones on non-freeway/interstate roadways. ......................................................................................................... 29 Figure 9. LTCCS crashes in or near work zones on non-freeway/interstate roadways based on potential influence of the work zone. ................................................................................................... 30 Figure 10. Conceptual operation of the portable queue warning system. ................................................... 37 Figure 11. Portable rumble strips used upstream of temporary lane closures on I-35. .............................. 38 Figure 12. Illustration of the manual queue detection process for each temporary nighttime lane closure segment. .......................................................................................... 39 Figure 13. Method of estimating expected crashes per night within lane closure analysis section. .......... 41 Figure 14. Effect of safety treatments upon crash severity during hours of queuing and non-queuing. .... 44 Figure 15. Work Zone Linear Referencing. ............................................................................................... 47 Figure 16. Estimated effects of median shoulder width before and during the work zones at the test sections (based on model 1) as compared to the HSM CMF. .............................................. 57 Figure 17. Estimated effects of outside shoulder width before and during the work zones at the test sections (based on model 1) as compared to the HSM CMF. .............................................. 57 Figure 18. Predicted crashes on 4-lane freeway segments. ........................................................................ 59 Figure 19. Predicted crashes on 6-lane freeway segments. ........................................................................ 59 Figure 20. Average effect of work zones upon crashes predicted on 4-lane freeway segments. ................ 60 Figure 21. Average effect of work zones upon crashes predicted on 6-lane freeway segments. ................ 61