Crash Modification Factors in the Highway Safety Manual: Resources for Evaluation (2023) / Chapter Skim
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Appendix M Calibration of Prediction Models of Rural and Urban Intersections for the 2nd Edition of the HSM
Appendix M Calibration of Prediction Models of Rural and Urban Intersections for the 2nd Edition of the HSM
Pages 299-374
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From page 299... ...
Appendix M Calibration of Prediction Models of Rural and Urban Intersections for the 2nd Edition of the HSM M-1
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M-59 5.7 Urban Arterial, 3-Leg Stop Controlled Intersections (UrbArt-3ST)
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Base Condition SPFs, All Way Stop Controlled Intersections............................................... M-27 Table 26.
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Calibration Results and Recommended Calibration Factors, All Way Stop Controlled Intersections ..................................................................................................................................... M-39 Table 41.
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M-62 Table 81. UrbArt-3ST Left Turn Bay Approach 2, estimate (standard error)
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From page 304... ...
Due to small sample sizes that would result by limiting the sites to only those fitting the base conditions and the AADT ranges used for SPF estimation, all intersections were included (including those outside of AADT ranges) , and the appropriate CMFs applied.
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From page 305... ...
the base conditions, for which CMFs are available, are as follows: β’ No lighting. β’ 2-lanes on the major road and 2-lanes on the minor road For all way stop controlled intersections on rural two-lane roads and urban arterials (Rur4Leg-AWSC, Urb3Leg-AWSC, Urb4Leg-AWSC)
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From page 306... ...
The research team conduced a sensitivity analysis to determine the effect of minor road AADTs on the calibration factors and found variations in calibration factors to be in the Β±2% range for the various randomly generated minor road AADT samples. Based on this minimal variation in the effects of minor road AADT on the calibration factors, the research team went ahead with including all urban arterial intersections with interpolated minor road AADTs in cases where minor road AADTs were missing.
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From page 307... ...
Major Road AADT Minor Road AADT Intersection Type Min Max Mean Min Max Mean Rur2L-3ST 308 20092 3033 4 3064 360 Rur2L-3SG 2900 23591 11334 100 2320 4568 Rur2L-4ST 147 8461 1843 4 4740 396 Rur2L-4SG 910 14790 5345 95 11641 2477 RurML-3ST 1325 36000 11651 3 5800 760 RurML-3SG 1001 56000 15928 101 27000 5040 RurML-4ST 2422 34500 10803 25 4654 589 RurML-4SG 880 12420 4986 157 7992 1902 UrbArt-3ST 270 38460 8187 33 18460 2137 UrbArt-3SG 3050 32109 12363 110 18415 4077 UrbArt-4ST 450 37301 8251 50 13773 2088 UrbArt-4SG 1810 34960 11067 72 27228 3803 UrbArt6+-3ST 10760 66800 37072 100 8589 1247 UrbArt6+-3SG 8755 94000 38791 98 31000 5455 UrbArt6+-4ST 12668 54600 33249 118 4600 1245 UrbArt6+-4SG 7090 137550 44658 86 68343 14188 UrbArtOW-3ST 98 42631 13234 17 13340 1081 UrbArtOW-4ST 345 23365 8718 75 19192 1413 UrbArtOW-4SG 130 98826 16993 103 77000 10538 Rur4Leg-AWSC 421 12983 3357 130 9985 1873 Urb3Leg-AWSC 175 20131 5491 151 11000 3411 Urb4Leg-AWSC 1150 12955 6008 400 11982 3503 Rur-RndAbt n/a n/a 8829 n/a n/a 4059 Urb-RndAbtSL n/a n/a 7687 n/a n/a 4035 Urb-RndAbtML n/a n/a 11712 n/a n/a 5760 Table 3 shows the sum of crashes by crash and severity type for intersections on rural highways (Rur2L3ST, Rur2L-3SG, Rur2L-4ST, Rur2L-4SG, RurML-3ST, RurMl-3SG, RurML-4ST, and RurML-4SG) in the calibration dataset.
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From page 308... ...
Summary of Crash for Roundabouts Crash Crash Severity Intersection Type Type Total F&I PDO Rur-RndAbt All 436 151 275 Urb-RndAbtSL All 884 154 708 Urb-RndAbtML All 84 18 64 Table 5 shows the sum of crashes by severity type for intersections on urban arterials (UrbArt-3ST, UrbArt-3SG, UrbArt-4ST, UrbArt-4SG, UrbArt6+-3ST, UrbArt6+-3SG, UrbArt6+-4ST, UrbArt6+-4SG, UrbArtOW-3ST, UrbArtOW-4ST, and UrbArtOW-4SG) in the calibration dataset.
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From page 309... ...
Summary of Crash Data for All Way Stop Controlled Intersections Intersection Type Crash Type/Severity Sum of Crashes Rur4Leg-AWSC All KABCO 1125 Urb3Leg-AWSC All KABCO 37 Urb4Leg-AWSC All KABCO 53 M-11
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ππ Γ e π΄π΄π΄π΄π΄π΄π΄π΄π‘π‘π‘π‘π‘π‘ ΓοΏ½ οΏ½ π΄π΄π΄π΄π΄π΄π΄π΄π‘π‘π‘π‘π‘π‘ Tables 16 to 19 present the parameter estimates (and standard errors in parentheses) for the urban arterial intersections base condition SPFs developed in NCHRP 17-62.
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ππππππππππππ ππππ πΎπΎπΎπΎπ΅π΅ ππππππππβππππ ππππ π‘π‘βππ ππππππππ π π π π π π Table 7. Base Condition SPFs, Rur2L-3ST Crash Type Severity b0 b1 b2 b3 k -7.924 0.656 0.295 0.622 KABCO (0.857)
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(0) # Not significant at 90th percentile confidence interval M-14
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* Poisson distribution used; scale = square root of Deviance/DOF # Not significant at 90th percentile confidence interval M-15
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(0.000) # Not significant at 90th percentile confidence interval M-16
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* Poisson distribution used; scale = square root of Deviance/DOF # Not significant at 90th percentile confidence interval M-17
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(0.000) # Not significant at 90th percentile confidence interval M-18
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# Not significant at 90th percentile confidence interval.
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# Not significant at 90th percentile confidence interval.
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# Not significant at 90th percentile confidence interval M-21
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(4.2722) SV = Single vehicle crashes SD = Same direction crashes OD = Opposite direction crashes ID = Intersecting direction crashes M-22
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(4.1273) SV = Single vehicle crashes SD = Same direction crashes OD = Opposite direction crashes ID = Intersecting direction crashes M-23
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(1.3915) OD KA Model did not converge ID KABCO Could not obtain useful model ID KABC Could not obtain useful model ID KAB Could not obtain useful model ID KA Could not obtain useful model SV = Single vehicle crashes SD = Same direction crashes OD = Opposite direction crashes ID = Intersecting direction crashes M-24
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( .3125) ID KA A Model did not converge SV = Single vehicle crashes SD = Same direction crashes OD = Opposite direction crashes ID = Intersecting direction crashes For intersections on urban arterials with 6+ lanes (UrbArt6+-3ST, UrbArt6+-3SG, UrbArt6+-4ST, and UrbArt6+-4SG)
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for the base condition SPFs developed in NCHRP 17-58 for intersections on urban arterials with 6+ lanes. Table 22.
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Base Condition SPFs, All Way Stop Controlled Intersections Crash Intersection Type b0 b1 b2 b3 k Severity -9.67 1.12 0.39 Rur4Leg-AWSC Total - (1.09)
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for the base condition SPFs developed in NCHRP 17-70 for rural and urban roundabouts. Table 26.
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Use the calibration factors recommended under notes SV = Single vehicle crashes SD = Same direction crashes OD = Opposite direction crashes ID = Intersecting direction crashes M-29
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The number of crashes are low leading to unreliable calibration factors. Use the calibration factors recommended under notes SV = Single vehicle crashes SD = Same direction crashes OD = Opposite direction crashes ID = Intersecting direction crashes M-30
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The number of crashes are low leading to unreliable calibration factors. Use the calibration factors recommended under notes SV = Single vehicle crashes SD = Same direction crashes OD = Opposite direction crashes ID = Intersecting direction crashes M-31
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The number of crashes are low leading to unreliable calibration factors. Use the calibration factors recommended under notes SV = Single vehicle crashes SD = Same direction crashes OD = Opposite direction crashes ID = Intersecting direction crashes M-32
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The number of crashes are low leading to unreliable calibration factors. Use the calibration factors recommended under notes SV = Single vehicle crashes SD = Same direction crashes OD = Opposite direction crashes ID = Intersecting direction crashes M-33
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Use the calibration factors recommended under notes SV = Single vehicle crashes SD = Same direction crashes OD = Opposite direction crashes ID = Intersecting direction crashes M-34
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Use the calibration factors recommended under notes SV = Single vehicle crashes SD = Same direction crashes OD = Opposite direction crashes ID = Intersecting direction crashes M-35
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The number of crashes are low leading to unreliable calibration factors. Use the calibration factors recommended under notes SV = Single vehicle crashes SD = Same direction crashes OD = Opposite direction crashes ID = Intersecting direction crashes M-36
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The number of crashes are low leading to unreliable calibration factors. Use the calibration factors recommended under notes SV = Single vehicle crashes SD = Same direction crashes OD = Opposite direction crashes ID = Intersecting direction crashes M-37
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Use the calibration factors recommended under notes SV = Single vehicle crashes SD = Same direction crashes OD = Opposite direction crashes ID = Intersecting direction crashes M-38
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of Observed Total Predicted Total Calibration Notes Type Intersections Crashes Crashes Factors UrbArtOW-3ST^ 6 - - UrbArtOW-4ST^ 5 - - Use with UrbArtOW-4SG# 14 1415 252.64 5.60 Caution ^ Cannot calculate reliable calibration factor due to low number of intersections and cashes available for calibration # Use with caution due to low number of intersections available for calibration Table 40. Calibration Results and Recommended Calibration Factors, All Way Stop Controlled Intersections Intersection No.
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From page 338... ...
The approach taken was to use sites that met all base conditions with the exception of the variable to which the adjustment factor applies. For example, where the adjustment factor for lighting is of interest, all the sites used meet the base conditions except for lighting where both sites with and without lighting are used.
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From page 339... ...
= function representing the relationship between crashes and the variable of interest Approach 3 For some variables, the recommended adjustment factors are not a single value or simple equation. In these cases, the approach to validation was to compare the sum of observed and predicted values for the base model and base model plus adjustment factor when applied to sites that did not meet the base conditions for the variable of interest.
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Table 44. Recommended Rur2L-3ST Left Turn Bay Adjustment Factors Crash Crash Type AF Severity All KABCO 0.56 KABC 0.45 KAB 0.45 KA 0.45 Single vehicle KABCO 0.61 Same direction KABCO 0.45 Opposing direction KABCO 0.69 Intersecting direction KABCO 0.39 Approaches 1 and 2 were both applied.
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From page 341... ...
(ππππππ ) πππππππ½π½βπΏπΏπΏπΏπΏπΏπΏπΏ ππππππππ π΅π΅π΅π΅π΅π΅ where ππππππ = the calibrated base condition SPF πΏπΏπΏπΏπΏπΏπΏπΏ ππππππππ π΅π΅π΅π΅π΅π΅ = 1 if left turn bay is present, 0 if not present ππππππππππππππππππππππππππππ = the overdispersion parameter of the negative binomial model Table 46 provides the parameter estimates and the implied adjustment factor for All KABCO crashes.
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Table 48. Rur2L-3ST Right Turn Bay Approach 1 Calibration Observed Crashes Predicted Crashes Factors Crash Implied Crash Type RTB RTB RTB RTB RTB RTB Severity AF Present Not Present Not Present Not Present Present Present All KABCO 7 302 5.76 249.34 1.22 1.21 1.00 KABC 1 103 2.12 93.03 0.47 1.11 0.43 KAB 0 48 1.13 44.10 n/a 1.09 n/a KA 0 5 0.14 6.79 n/a 0.74 n/a Single vehicle KABCO 4 82 2.15 96.11 1.86 0.85 2.18 Same KABCO 2 121 1.96 106.26 1.02 1.14 0.90 direction M-44
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From page 343... ...
Table 49. Recommended Rur2L-3ST Skew Angle Adjustment Factors Crash Crash Type AF Severity All KABCO ππππππ[0.0040 π₯π₯ π π π π π π π π ]
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From page 344... ...
Recommended Rur2L-4ST Lighting Adjustment Factors Crash Type Crash AF Severity All KABCO Use equation above KABC Use equation above KAB Same as KABC KA Same as KABC There were 10 sites which met all base conditions (i.e., base conditions of all other variables) except for the lighting.
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From page 345... ...
Table 53. Recommended Rur2L-4ST Right Turn Bay Adjustment Factors Crash Crash Type AF Severity All KABCO 0.85 KABC 0.77 KAB 0.77 KA 0.77 Single vehicle KABCO 0.94 Same direction KABCO 0.74 Opposing direction KABCO 0.74 Intersecting direction KABCO 0.91 There were 10 sites which met all base conditions (i.e., base conditions of all other variables)
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From page 346... ...
Table 55. Recommended Rur2L-4ST Skew Angle Adjustment Factors Crash Crash Type AF Severity All KABCO ππππππ[0.0054 π₯π₯ π π π π π π π π ]
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From page 347... ...
Recommended Rur2L-4SG Lighting Adjustment Factors Crash Type Crash AF Severity All KABCO Use equation above KABC Use equation above KAB Same as KABC KA Same as KABC The recommended adjustment factors could not be validated since the dataset used for calibration did not have any variation for lighting, i.e., all sites in the calibration dataset (that met the base conditions for all other variables except for lighting) met the base condition of absence of lighting.
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From page 348... ...
Rur2L-4SG Left Turn Bay Approach 1 Calibration Observed Crashes Predicted Crashes Factors Crash Implied Crash Type LTB LTB LTB LTB LTB LTB Severity AF Present Not Present Not Present Not Present Present Present All KABCO 653 478 211.33 138.46 3.09 3.45 0.89 KABC 204 153 66.57 35.63 3.06 4.29 0.71 KAB 60 45 31.85 19.88 1.88 2.26 0.83 KA 11 9 6.37 4.76 1.73 1.89 0.91 Same KABCO 254 199 165.62 80.92 1.53 2.46 0.62 direction The results from Approach 1 show that the implied adjustment factors are very close in effect and magnitude to the recommended calibration factors. In approach 2 negative binomial models were calibrated for All KABCO and SD KABCO crashes.
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From page 349... ...
Rur2L-4SG Right Turn Bay Approach 1 Calibration Observed Crashes Predicted Crashes Factors Crash Implied Crash Type RTB RTB RTB RTB RTB RTB Severity AF Present Not Present Not Present Not Present Present Present All KABCO 56 478 20.02 138.46 2.80 3.45 0.81 KABC 13 153 5.04 35.63 2.58 4.29 0.60 KAB 5 45 2.87 19.88 1.74 2.26 0.77 KA 1 9 0.67 4.76 1.49 1.89 0.79 Based on the results from Approach 1, there is some evidence that the effect and magnitude of the adjustment factor is reasonable and reasonably similar to the recommended adjustment factors. As such it may be cautiously considered that the adjustment factor for all crashes for installation of right turn bay are validated.
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From page 350... ...
Recommended RurML-3ST Lighting Adjustment Factors Crash Type Crash AF Severity All KABCO Use equation above KABC Use equation above KAB Same as KABC KA Same as KABC There were 3 sites which met all base conditions (i.e., base conditions of all other variables) except for the left turn bay and lighting.
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From page 351... ...
Table 65. Recommended RurML-3ST Right Turn Bay Adjustment Factors Crash Crash Type AF Severity All KABCO 0.85 KABC 0.77 KAB 0.77 KA 0.77 Single vehicle KABCO 0.82 Same direction KABCO 0.79 There were 5 sites which met all base conditions (i.e., base conditions of all other variables)
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From page 352... ...
Table 66. Recommended RurML-3ST Skew Angle Adjustment Factors Crash Type Crash AF Severity All KABCO Use equation above KABC Use equation above KAB Same as KABC KA Same as KABC There were 6 sites which met all base conditions (i.e., base conditions of all other variables)
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From page 353... ...
Recommended RurML-4ST Lighting Adjustment Factors Crash Type Crash AF Severity All KABCO Use equation above KABC Use equation above KAB Same as KABC KA Same as KABC There were 2 sites which met all base conditions (i.e., in this case base condition for right turn bay) except for the lighting.
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From page 354... ...
Table 70. Recommended RurML-4ST Right Turn Bay Adjustment Factors Crash Crash Type AF Severity All KABCO 0.85 KABC 0.77 KAB 0.77 KA 0.77 Single vehicle KABCO 0.94 Same direction KABCO 0.74 Opposing direction KABCO 0.74 Intersecting direction KABCO 0.91 There were 20 sites which met all base conditions (i.e., in this case base condition for lighting)
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From page 355... ...
. The recommended adjustment factors are shown in Table 72.
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From page 356... ...
Recommended RurML-4SG Left Turn Bay Adjustment Factors Crash Crash Type AF Severity All KABCO 0.82 KABC 0.89 KAB 0.89 KA 0.89 Same direction KABCO 0.72 There were 6 sites which met all base conditions (i.e., base conditions of all other variables) except for the left turn bay.
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From page 357... ...
Table 75. Recommended RurML-4SG Right Turn Bay Adjustment Factors Crash Crash Type AF Severity All KABCO 0.96 KABC 0.91 KAB 0.91 KA 0.91 The recommended adjustment factors could not be validated since the dataset used for calibration did not have any variation for right turn bay, i.e., all sites in the calibration dataset that met the base condition for all other variables except for right turn bay also met the base condition of absence of right turn bay.
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From page 358... ...
Recommended UrbArt-3ST Lighting Adjustment Factors Crash Type Crash AF Severity All KABCO Use equation above KABC Use equation above KAB Same as KABC KA Same as KABC With the default values the Adjustment Factor for lighting is 1.23 for KABCO crashes and 1.07 for KABC crashes (Note that since default value for the proportion of all crashes that have KABC severity is not available, the default KABCO adjustment factor was calculated as a product of default adjustment factors for KABC and PDO crashes)
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From page 359... ...
Table 79. Recommended UrbArt-3ST Left Turn Bay Adjustment Factors Crash Crash Type AF Severity All KABCO 0.63 KABC 0.49 KAB 0.49 KA 0.49 Approaches 1 and 2 were both applied.
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From page 360... ...
(ππππππ ) πππππππ½π½βπΏπΏπΏπΏπΏπΏπΏπΏ ππππππππ π΅π΅π΅π΅π΅π΅ where ππππππ = the calibrated base condition SPF πΏπΏπΏπΏπΏπΏπΏπΏ ππππππππ π΅π΅π΅π΅π΅π΅ = 1 if left turn bay is present, 0 if not present ππππππππππππππππππππππππππππ = the overdispersion parameter of the negative binomial model Table 81 provides the parameter estimates and the implied adjustment factor for All KABCO crashes.
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From page 361... ...
Recommended UrbArt-3ST Right Turn Bay Adjustment Factors Crash Crash Type AF Severity All KABCO 0.85 KABC 0.77 KAB 0.77 KA 0.77 There were 35 sites which met all base conditions (i.e., base conditions of all other variables) except for the right turn bay.
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From page 362... ...
Table 86. UrbArt-3SG Right Turn Bay Approach 1 Calibration Observed Crashes Predicted Crashes Factors Crash Implied Crash Type RTB RTB RTB RTB RTB RTB Severity AF Present Not Present Not Present Not Present Present Present All KABCO 336 6 316.54 3.55 1.06 0.24 4.39 KABC 96 2 96 0.77 1.36 0.37 3.66 KAB 20 0 20 0.34 0.63 n/a n/a KA 2 0 2 0.07 0.31 n/a n/a M-64
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From page 363... ...
Red Light Running Camera Enforcement The base condition is the no red light running camera enforcement. Recommended adjustment factors are computed using the following equations: πΆπΆπΆπΆπΆπΆππππ,π§π§ = πππ π π π Γ πΆπΆπΆπΆπΆπΆπ π π π ,π§π§ + πππ π π π Γ πΆπΆπΆπΆπΆπΆπ π π π ,π§π§ + ππππππ Γ πΆπΆπΆπΆπΆπΆππππ + ππππππ Γ πΆπΆπΆπΆπΆπΆππππ where πΆπΆπΆπΆπΆπΆππππ,π§π§ = CMF for all crash types and severity category z, πππ π π π = proportion of crashes that are single vehicle, πππ π π π = proportion of crashes that are same direction, ππππππ = proportion of crashes that are opposing direction, and ππππππ = proportion of crashes that are intersecting direction.
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From page 364... ...
Right Turn on Red Prohibition The base condition is right turn on red allowed on all approaches. Recommended adjustment factors are computed using the following equations: πΆπΆπΆπΆπΆπΆππππ,π§π§ = πππ π π π Γ πΆπΆπΆπΆπΆπΆπ π π π ,π§π§ + πππ π π π Γ πΆπΆπΆπΆπΆπΆπ π π π ,π§π§ + ππππππ Γ πΆπΆπΆπΆπΆπΆππππ + ππππππ Γ πΆπΆπΆπΆπΆπΆππππ where πΆπΆπΆπΆπΆπΆππππ,π§π§ = CMF for all crash types and severity category z, πππ π π π = proportion of crashes that are single vehicle, πππ π π π = proportion of crashes that are same direction, ππππππ = proportion of crashes that are opposing direction, and ππππππ = proportion of crashes that are intersecting direction.
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From page 365... ...
, πΆπΆπΆπΆπΆπΆππππ,πΎπΎπΎπΎπΎπΎπΎπΎ = CMF for opposing direction crash types with KABC severity, πππ‘π‘π‘π‘|ππππ = proportion of opposing direction crashes that are right turn related (default value = 0.029) , πΆπΆπΆπΆπΆπΆππππ,πΎπΎπΎπΎπΎπΎπΎπΎ = CMF for intersecting direction crash types with KABC severity, πππ‘π‘π‘π‘|ππππ = proportion of intersecting direction crashes that are right turn related (default value = 0.191)
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From page 366... ...
5.9 Urban Arterial, 4-Leg Stop Controlled Intersections (UrbArt-4ST) Lighting The base condition is the presence of lighting.
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From page 367... ...
UrbArt-4ST Lighting Approach 1 Observed Crashes Predicted Crashes Calibration Factors Crash Lighting Lighting Lighting Lighting Lighting Lighting Implied Crash Type Severity Not Present Not Not Present AF Present Present Present Present All KABCO 73 128 78.26 108.29 0.93 1.18 0.79 KABC 32 47 23.38 38.43 1.37 1.22 1.12 For total crashes (i.e., All KABCO) the implied adjustment factor for the absence of lighting is 0.79 (counterintuitive to the recommended adjustment factor of 1.22)
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From page 368... ...
Table 92. UrbArt-4ST Left Turn Bay Approach 1 Calibration Observed Crashes Predicted Crashes Factors Crash Implied Crash Type LTB LTB LTB LTB LTB LTB Severity AF Present Not Present Not Present Not Present Present Present All KABCO 84 128 7.49 108.29 11.21 1.18 9.49 KABC 36 47 3.08 38.43 11.69 1.22 9.56 KAB 4 17 0.84 10.5 4.76 1.62 2.94 KA 0 1 0.02 0.28 n/a 3.57 n/a It can be seen that the 1 site where left turn bay was present was a high crash site and skews the results of the analysis.
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From page 369... ...
Recommended UrbArt-4SG Lighting Adjustment Factors Crash Type Crash AF Severity All KABCO Use equation above KABC Use equation above KAB Same as KABC KA Same as KABC The recommended adjustment factors could not be validated since the dataset used for calibration did not have any variation for lighting, i.e., all sites in the calibration dataset (that met the base conditions for all other variables) met the base condition of presence of lighting.
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From page 370... ...
Table 96. UrbArt-4SG Left Turn Bay Approach 1 Calibration Observed Crashes Predicted Crashes Factors Crash Implied Crash Type LTB LTB LTB LTB LTB LTB Severity AF Present Not Present Not Present Not Present Present Present All KABCO 1203 48 1092.77 76.02 1.10 0.63 1.74 KABC 442 11 292.88 18.27 1.51 0.60 2.51 KAB 91 2 117.53 8.05 0.77 0.25 3.12 KA 7 0 20.79 1.61 0.34 n/a n/a It can be seen that the 3 sites where left turn bay was not present were low crash sites and skew the results of the analysis.
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From page 371... ...
UrbArt-4SG Right Turn Bay Approach 1 Calibration Observed Crashes Predicted Crashes Factors Crash Implied Crash Type RTB RTB RTB RTB RTB RTB Severity AF Present Not Present Not Present Not Present Present Present All KABCO 45 48 73.57 76.02 0.61 0.63 0.97 KABC 10 11 19.32 18.27 0.52 0.60 0.86 KAB 3 2 7.91 8.05 0.38 0.25 1.53 KA 0 0 1.4 1.61 n/a n/a n/a For total crashes (i.e., All KABCO) the implied adjustment factor for the presence of right turn bay is 0.97 (very similar to the recommended adjustment factor of 0.96)
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From page 372... ...
Recommended UrbArt-3SG Red Light Camera Enforcement Adjustment Factors Crash Type Crash AF Severity All KABCO Use equation above KABC Use equation above KAB Use equation above KA Use equation above Single Vehicle KABCO 1.00 KABC 1.00 KAB 1.00 KA 1.00 Same Direction KABCO 1.155 KABC 1.234 KAB 1.240 KA 1.24 Opposing Direction KABCO Use equation above KABC Use equation above KAB Use equation above KA Use equation above Intersecting Direction KABCO Use equation above KABC Use equation above KAB Use equation above KA Use equation above The recommended adjustment factors could not be validated since the dataset used for calibration did not have any variation for red light running camera enforcement, i.e., all sites in the calibration dataset had no red light running camera enforcement.
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From page 373... ...
, πΆπΆπΆπΆπΆπΆππππ,πΎπΎπΎπΎπΎπΎπΎπΎ = CMF for opposing direction crash types with KABC severity, πππ‘π‘π‘π‘|ππππ = proportion of opposing direction crashes that are right turn related (default value = 0.029) , πΆπΆπΆπΆπΆπΆππππ,πΎπΎπΎπΎπΎπΎπΎπΎ = CMF for intersecting direction crash types with KABC severity, πππ‘π‘π‘π‘|ππππ = proportion of intersecting direction crashes that are right turn related (default value = 0.191)
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From page 374... ...
Recommended UrbArt-3SG Right Turn on Red Prohibition Adjustment Factors Crash Type Crash AF Severity All KABCO Use equation above KABC Use equation above KAB Use equation above KA Use equation above Single Vehicle KABCO 1.00 KABC 1.00 KAB 1.00 KA 1.00 Same Direction KABCO Use equation above KABC Use equation above KAB Use equation above KA Use equation above Opposing Direction KABCO Use equation above KABC Use equation above KAB Use equation above KA Use equation above Intersecting Direction KABCO Use equation above KABC Use equation above KAB Use equation above KA Use equation above The recommended adjustment factors could not be validated since the dataset used for calibration did not have any variation for right turn on red prohibition, i.e., all sites in the calibration dataset (that met the base conditions for all other variables) met the base condition of right turn on red allowed on all approaches.
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