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From page 59... ... NCHRP 17-59 59 CHAPTER 3: FINDINGS AND APPLICATION OVERVIEW Chapter 3 presents the model estimation results that describe the relationship between target crash frequency, available ISD, and other intersection characteristics. Results are presented for target crashes and target fatal and injury crashes (i.e., a subset of target crashes that involve at least one fatality or injury of any level) Read the entire page →
From page 60... ... NCHRP 17-59 60 ISD is shorter, and decreases as ISD increases (i.e., the safety benefit of increasing ISD from 300 to 600 feet is substantially larger than the safety benefit of increasing ISD from 1000 to 1300 feet) Read the entire page →
From page 61... ... NCHRP 17-59 61 Table 17. Model Estimation Results for Expected Number of Target Crashes. Read the entire page →
From page 62... ... NCHRP 17-59 62 where: ܥܯܨ் = CMF for target crashes for an approach direction. ܥܯܨ்೔ = Target crash CMF for condition of interest i (where i = 1 for proposed condition and i = 2 for existing condition) Read the entire page →
From page 63... ... NCHRP 17-59 63 The other key ISD-related findings of the target crash model remain the same for the target fatal and injury crash model, including the following:  The expected number of fatal and injury target crashes increases as available ISD decreases.  ISD is associated with expected target fatal and injury crash frequency in a non-linear fashion. Read the entire page →
From page 64... ... NCHRP 17-59 64 ܥܯܨ்ிூ ൌ ஼ெி೅ಷ಺భ஼ெி೅ಷ಺మ (5) ܥܯܨ்ிூ = CMF for target fatal and injury crashes for an approach direction. Read the entire page →
From page 65... ... NCHRP 17-59 65 "3." This finding supports the hypothesis that objects in the roadside could be beneficial in helping drivers that are stopped on the minor road estimate the speeds of and distances to approaching vehicles on the major road approaches. Future research to build on this finding is needed. Read the entire page →
From page 66... ... NCHRP 17-59 66  Low major road AADT. The major road AADT is less than or equal to 5,000. Read the entire page →
From page 67... ... NCHRP 17-59 67 benefit may be realized for ISD beyond this value. The value 1,320 is used as the base condition for the charts, but direct comparisons may be made between two alternative CMFs on the chart. Read the entire page →
From page 68... ... NCHRP Figure 11 findings crashes a and injur example the guida Guidance 17-59 through Fi for target an nd differ by y crashes an application nce docume for Evalua gure 22 prov d target fata major road d also differ for a one dir nt develope ting the Safe Figure 10 ide the fina l and injury posted spee by major ro ection sight d as part of ty Impacts o 68 . Sample C l charts deve crashes. Read the entire page →
From page 69... ... N CHRP 17-59 Figure 11. CMF for Target Cra 69 shes when Posted Speed Equ als 35 mph. Read the entire page →
From page 70... ... N CHRP 17-59 Figure 12. CMF for Target Cra 70 shes when Posted Speed Equ als 40 mph. Read the entire page →
From page 71... ... N CHRP 17-59 Figure 13. CMF for Target Cra 71 shes when Posted Speed Equ als 45 mph. Read the entire page →
From page 72... ... N CHRP 17-59 Figure 14. CMF for Target Cra 72 shes when Posted Speed Equ als 50 mph. Read the entire page →
From page 73... ... N CHRP 17-59 Figure 15. CMF for Target Cra 73 shes when Posted Speed Equ als 55 mph. Read the entire page →
From page 74... ... N CHRP 17-59 Figure 16. CMF for Target Cra 74 shes when Posted Speed Equ als 60 mph. Read the entire page →
From page 75... ... N CHRP 17-59 Figure 17. CMF for Target Fatal and In 75 jury Crashes when Posted Sp eed Equals 35 mph. Read the entire page →
From page 76... ... N CHRP 17-59 Figure 18. CMF for Target Fatal and In 76 jury Crashes when Posted Sp eed Equals 40 mph. Read the entire page →
From page 77... ... N CHRP 17-59 Figure 19. CMF for Target Fatal and In 77 jury Crashes when Posted Sp eed Equals 45 mph. Read the entire page →
From page 78... ... N CHRP 17-59 Figure 20. CMF for Target Fatal and In 78 jury Crashes when Posted Sp eed Equals 50 mph. Read the entire page →
From page 79... ... N CHRP 17-59 Figure 21. CMF for Target Fatal and In 79 jury Crashes when Posted Sp eed Equals 55 mph. Read the entire page →
From page 80... ... N CHRP 17-59 Figure 22. CMF for Target Fatal and In 80 jury Crashes when Posted Sp eed Equals 60 mph. Read the entire page →
From page 81... ... NCHRP Example A three-l 7,000 and change in condition Target C Using Fig ISD of 40 0.77. Thi vehicles Target C Use Equa 17-59 – One Dire eg intersecti a major ro average tar of 400 feet rashes – Gr ure 23, the 0 feet is 1.4 s factor app approaching rashes - CM tion 3 to co ction ISD U on with stop ad posted sp get crash fre to a propos aphical App CMF for the 6. Read the entire page →
From page 82... ... NCHRP The follo  T  T  T  T  T The CMF The CMF The targe The targe involving CMF can Equation 17-59 wing condit he posted sp his site uses he proposed he existing I he base ISD for the pro for the exi t crash CMF t crashes CM vehicles fr be compute 10. ions apply: eed is 55 m the MidAA ISD is 750 SD is 400 f is 1,320 fee posed ISD c sting ISD is is calculat F for impr om the mino d directly b ph. Read the entire page →
From page 83... ... NCHRP 17-59 83 GUIDANCE DOCUMENT DEVELOPMENT An additional intent of this project was to develop a practice-ready guidance document for application of the model results and any supplementary relationships identified as part of the crash analysis. The development of the guidance document considered the current practices of agencies, the intended audience, and the various situations where ISD is used (e.g., design, planning, operational changes, and safety remediation) Read the entire page →
From page 84... ... NCHRP 17-59 84 the guidance document to be well laid out and were pleased with the completeness and succinctness of the charts. Additionally, they reported that the guidance document would be helpful and applicable in the field. Read the entire page →
From page 85... ... NCHRP 17-59 85 separately. The project team agreed with participants that this specific crash type is too detailed for the purpose of the guidance document. Read the entire page →
From page 86... ... NCHRP 17-59 86  Chapter III (Safety Performance and Intersection Sight Distance) provides practitioners information on the anticipated impact on crashes at an intersection from changing the sight distance. Read the entire page →

From page 59...

... NCHRP 17-59 59 CHAPTER 3: FINDINGS AND APPLICATION OVERVIEW Chapter 3 presents the model estimation results that describe the relationship between target crash frequency, available ISD, and other intersection characteristics. Results are presented for target crashes and target fatal and injury crashes (i.e., a subset of target crashes that involve at least one fatality or injury of any level)