Further Development of the Safety and Congestion Relationship for Urban Freeways (2014) / Chapter Skim
Currently Skimming:
Pages 15-20
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 15... ...
15 This chapter addresses interpreting the state-by-state results presented in Chapter 2. Comparison of the SafetyCongestion Relationships Between States Chapter 2 presented the safety-congestion relationships developed in both the original Phase 2 research and in the new Task IV-5 research.
|
From page 16... ...
16 crash rate for the three metropolitan areas and then averaging the individual data points. With this translation completed, the results are representative of a freeway system with a total crash rate of 1.86 crashes per MVMT, a fatal-and-injury crash rate of 0.42 crashes per MVMT, and a property-damage- only crash rate of 0.82 crashes per MVMT, which represents the average freeway crash rate for Seattle, Minneapolis– St.
|
From page 17... ...
17 Over the entire traffic density range, crash rates are expressed as follows in Equations 3.4 through 3.6, based on Table 3.1: Total crashes per MVMT 0.72 if Density 20 pc mi ln 2.190 0.1979 0.00728 5.34 10 5.77 if Density 76 pc mi ln (3.4) 2 5 3D D D = < − × + × − × × > − FI crashes per MVMT 0.24 if Density 20 pc mi ln 0.831 0.0718 0.00246 1.76 10 1.86 if Density 76 pc mi ln (3.5)
|
From page 18... ...
18 Safety-Congestion Relationships for Specific Nonrecurrent Congestion Scenarios The results shown in Figures 3.1 and 3.2 incorporate the effects of both recurrent and nonrecurrent congestion as well as many periods of uncongested flow. Since the focus of Project L07 is on nonrecurrent congestion, a further analysis was conducted to check whether the results shown in Figures 3.1 and 3.2 are representative of nonrecurrent congestion.
|
From page 19... ...
19 overall data set (see Figure 2.3)
|
From page 20... ...
20 Nonrecurrent congestion related to crashes was identified by matching all periods of nonrecurrent congestion identified according to the rules presented above with the locations and times of crashes. Any nonrecurrent congestion was identified as crash-influenced if it occurred • In the same 15-min period as a crash or in one of the three subsequent 15-min periods; and • In the same freeway section as a crash or in any freeway section within 2 mi upstream of the freeway section where the crash occurred.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.