Diverging Diamond Interchange Informational Guide, Second Edition (2021) / Chapter Skim
Currently Skimming:
Pages 59-66
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 59... ...
59 Diverging diamond interchanges (DDIs) , like many alternative intersection and interchange designs, offer quantifiable safety benefits compared to conventional interchange designs.
|
From page 60... ...
60 Diverging Diamond Interchange Informational Guide Exhibit 4-1. Conflict point diagram for DDI.
|
From page 61... ...
Safety 61 diamond interchanges. However, if RTOR operations are allowed, rightturning drivers may look on the wrong side of the road when checking for conflicting vehicles because traffic is crossed over.
|
From page 62... ...
62 Diverging Diamond Interchange Informational Guide 4.1.4 Wrong-way Maneuvers At most interchanges, including conventional diamonds, wrongway maneuver concerns are primarily related to drivers entering the freeway in the wrong direction. There is nothing inherent about the design of the DDI that would increase the likelihood of this, and the channelization of movements may decrease the likelihood of wrongway maneuvers at freeway exit ramps.
|
From page 63... ...
Safety 63 Year of Report Author(s) Study Site Locations (# sites)
|
From page 64... ...
64 Diverging Diamond Interchange Informational Guide 30 2 0 0.20 0.26 0.25 1 0.30 0.39 0.38 2 0.45 0.59 0.58 1 0 0.25 0.30 0.29 1 0.38 0.46 0.44 2 0.56 0.69 0.67 0 0 0.32 0.35 0.34 1 0.47 0.53 0.51 2 0.70 0.81 0.79 35 2 0 0.28 0.38 0.36 1 0.41 0.58 0.55 2 0.61 0.89 0.84 1 0 0.34 0.45 0.42 1 0.51 0.68 0.64 2 0.76 1.04 0.98 0 0 0.43 0.53 0.49 1 0.64 0.80 0.75 2 0.96 1.21 1.14 40 2 0 0.38 0.57 0.52 1 0.56 0.87 0.79 2 0.83 1.32 1.22 1 0 0.47 0.67 0.61 1 0.70 1.02 0.93 2 1.04 1.55 1.42 0 0 0.59 0.78 0.71 1 0.87 1.19 1.09 2 1.30 1.81 1.66 45 2 0 0.51 0.86 0.75 1 0.76 1.30 1.15 2 1.14 1.97 1.77 1 0 0.64 1.00 0.88 1 0.95 1.52 1.35 2 1.42 2.31 2.07 0 0 0.80 1.17 1.03 1 1.19 1.78 1.58 2 1.77 2.70 2.41 Notes: 1 Number of through lanes at the DDI minus the number of through lanes at the interchange before conversion Total of both travel directions.
|
From page 65... ...
Safety 65 30 2 0 0.24 0.37 0.35 1 0.36 0.56 0.54 2 0.54 0.85 0.82 1 0 0.30 0.43 0.41 1 0.45 0.66 0.63 2 0.67 0.99 0.96 0 0 0.38 0.50 0.48 1 0.56 0.77 0.73 2 0.84 1.16 1.12 35 2 0 0.33 0.55 0.51 1 0.49 0.84 0.78 2 0.73 1.27 1.19 1 0 0.41 0.64 0.59 1 0.62 0.98 0.91 2 0.92 1.48 1.39 0 0 0.52 0.75 0.69 1 0.77 1.14 1.06 2 1.15 1.73 1.63 40 2 0 0.45 0.82 0.74 1 0.67 1.25 1.13 2 1.00 1.90 1.73 1 0 0.56 0.96 0.86 1 0.84 1.46 1.32 2 1.25 2.21 2.02 0 0 0.70 1.12 1.01 1 1.05 1.70 1.55 2 1.56 2.59 2.37 45 2 0 0.61 1.23 1.07 1 0.92 1.86 1.64 2 1.36 2.83 2.52 1 0 0.77 1.43 1.26 1 1.14 2.18 1.92 2 1.70 3.30 2.94 0 0 0.96 1.68 1.47 1 1.43 2.54 2.25 2 2.13 3.86 3.44 Notes: 1 Number of through lanes at the DDI minus the number of through lanes at the interchange before conversion Total of both travel directions.
|
From page 66... ...
66 Diverging Diamond Interchange Informational Guide The analysis results indicate that the conversion to DDI is often associated with a reduction in crashes; however, crash frequency may be increased for some combinations of higher cross road speed limit, one or more crossroad lanes dropped at the DDI, and the existing interchange having unsignalized terminals. "Crossroad lanes dropped" refer to lanes on the outside of the crossroad that drop a freeway onramp.
|
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.