Recommended Guidelines for Curb and Curb-Barrier Installations (2005) / Chapter Skim
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Pages 85-91
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From page 85... ...
The offset distance in Figure 44 refers to the distance between the face of the curb and the face of the guardrail, illustrated in Figure 45. As shown in Figure 44, a successful crash test is likely when the curb is positioned under the face of the guardrail for all speeds up to an operating speed of 100 km/h.
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From page 86... ...
Figure 46. Design chart for curb–guardrail combinations by operating speed and offset distance.
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From page 87... ...
As mentioned earlier, the NY curb is characterized by a very low tripping risk index, so it seems likely that some very flat-faced, low-height curbs can be used 2.5 m in front of a guardrail even on some higher speed roadways. In general, however, guardrails should be placed at least 4 m behind the curb on roads with operating speeds between 71 and 85 km/h unless testing or analysis of a specific curb indicates that it will perform satisfactorily.
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From page 88... ...
For example, if a certain road needs a curb height of 120 mm for hydrological reasons and the curb must be placed within the clear zone for the roadway, the diagram suggests that the curb slope be less than 0.3 for a low risk of tripping errant vehicles. Conclusions This section has presented an approximate method to numerically evaluate the tripping risk offered by different types of curbs.
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From page 89... ...
: Tripping Risk Index for the Curb Type (Average of the tripping risk of each test) : Tripping Risk Index for the Curb Type (Average of the tripping risk of each test)
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From page 90... ...
Figure 47. TRI as a linear function of curb height and slope.
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From page 91... ...
Curb geometric design diagram with respect to the tripping risk in nontracking impacts. Safety rank Curb type TRI 1 NYDOT NY 12.48 2 AASHTO G 40.06 3 AASHTO C 46.10 4 AASHTO B 56.76 5 AASHTO D 58.41 TABLE 42 Curb safety in nontracking impact scenarios
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