Validation of Accident Models for Intersections
FHWA Contact: John Doremi,
HRDI-10, (202) 493-3052, John.doremi@dot.gov
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3. RECALIBRATION (Continuation)
This research introduced two ways of deriving AMFs. One approach is to adopt the estimated parameter values from the statistically significant variables in the accident prediction models. The other approach uses a relatively untested regression procedure. Although in general the first approach is easier to apply, the second approach is recommended. This approach aims to attribute the difference between the observed number of crashes at a site and that predicted by a base model to the presence of non-base condition factors. This difference will explain a real effect of the presence of individual design features on safety.
Tables 185 through 187 compare the AMFs from the "Red Book" and those derived here. The AMFs from Harwood et al. are also shown in brackets.(5) As mentioned, none of the variables investigated showed any significant impact on safety for Type V sites, resulting in AMFs of one for these variables.
Compared to the previous works, for Types I and II, no AMF was estimated for SKEW. For right-turn lane on major roads, AMFs greater than one and less than one were estimated for Type II sites using the Group A dataset for the former and the Group B for the latter.
Whereas the "Red Book" provides separate AMFs for right-and left-turn lanes on major roads at Type II intersections, turning lanes at most sits in this dataset were provided on both approaches and separate effects could not be detected for one versus two approaches. SKEW did not provide a significant AMF different from 1 in the new data. And very few sites had deficient sight distance so an AMF could not be estimated.
For Type III and IV intersections, intersection angle (SKEW) was estimated as significant in the regression models. Right-turn lanes on major roads provided significant AMFs for Type IV intersections. For Type V intersections, no AMFs were found to be significantly different from 1.
Table 185. Comparison of Type I-II AMFs for TOTACC
|
AMF
|
"Red Book" and Harwood et al. (2002)
|
Full Models
|
Regression Models
|
|
Type I
|
Type II
|
Type I
|
Type II
|
Type I
|
Type II
|
|
SKEW
|
exp(0.004SKEW)
|
exp(0.0054SKEW)
|
Not calibrated
|
Not calibrated
|
1
|
1
|
|
RT MAJ
|
1.00 if none exist
0.95 on one approach
(0.86 on one approach)
0.90 on both approaches
(0.74 on both approaches)
|
0.88
|
1.19,0.861
|
1
|
0.71
|
|
LT MAJ
|
1.00 if none exist
0.78 if at least one exists
(0.56 if at least one exists)
|
1.00 if none exist
0.76 on one approach
(0.72 on one approach)
0.58 on both approaches
(0.52 on both approaches)
|
0.82
|
|
1
|
0.71
|
|
SIGHT DISTANCE
|
1.05 if limited in 1 quadrants
|
Not calibrated
|
Not calibrated
|
Not calibrated
|
Not calibrated
|
|
1.10 if limited in 2 quadrants
|
|
1.15 if limited in 3 quadrants
|
|
1.20 if limited in 4 quadrants
|
|
RT MIN
|
Not calibrated
|
Not calibrated
|
1.35
|
Not calibrated
|
1.48
|
1
|
|
HI1
|
exp(0.0263)
|
Not calibrated
|
Not calibrated
|
|
DRWY1
|
Not calibrated
|
1.13
|
|
MEDIAN
|
Not calibrated
|
1
|
0.77
|
1 Group A = 1.19, Group B = 0.86
Table 186. Comparison of Type III-V AMFs for TOTACC
|
AMF
|
"Red Book" and Harwood et al. (2002)
|
AMFs Derived From Full Models
|
AMFs Derived From Regression Models
|
|
Type III-IV
|
Type V
|
Type III
|
Type IV
|
Type V
|
Type III
|
Type IV
|
Type V
|
|
SKEW
|
None provided
|
1
|
exp(0.010SKEW)
|
Not calibrated
|
Not calibrated
|
1+(0.016*SKEW)/ (0.98+0.016*SKEW)
|
1+(0.053*SKEW)/ (1.43+0.053*SKEW)
|
1
|
|
RT MAJ
|
1.00 if none exist
0.975 on one approach (0.96 on one approach)
0.95 on both approaches (0.92 on both approaches)
|
Not calibrated
|
1
|
1
|
1
|
|
LT MAJ
|
1.00 if none exist
0.82 on one approach
0.67 on both approaches
|
0.71
|
1
|
1
|
|
SIGHT DISTANCE
|
1
|
1
|
1
|
1
|
|
COMDRWY1
|
Not calibrated
|
exp (0.0681COMDRWY1)
|
exp (0.0539 COMDRWY1)
|
Not calibrated
|
Not calibrated
|
Not calibrated
|
|
VEI1
|
exp(0.1081VEI1)
|
Not calibrated
|
|
MEDWIDTH1
|
exp (-0.0106MEDWDTH1)
|
|
MEDTYPE1
|
0.73
|
|
PKTRUCK
|
Not calibrated
|
exp (-0.0479PKTRUCK)
|
|
PKTHRU2
|
exp (0.0249PKTHRU2)
|
|
PKLEFT
|
exp (0.0229PKLEFT)
|
|
SDR2
|
exp(-0.0003SDR2)
|
|
LIGHT
|
|
0.75
|
|
HEICOM
|
exp (-0.0288HEICOM)
|
Table 187. Comparison of AMFs for INJACC
|
AMF
|
"Red Book"
|
AMFs Derived From Full Models
|
AMFs Derived From Regression Models
|
|
Type I - V
|
Type I
|
Type II
|
Type III
|
Type IV
|
Type V
|
Type I
|
Type II
|
Type III
|
Type IV
|
|
SKEW
|
None provided
|
Not calibrated
|
Not calibrated
|
exp(0.0163SKEW)
|
Not calibrated
|
Not calibrated
|
1
|
1
|
1+(0.017SKEW)/ (0.52+0.017SKEW)
|
1+(0.048SKEW)/ (0.72+0.048SKEW)
|
|
RT MAJ
|
0.87
|
0.85
|
Not calibrated
|
1
|
1
|
1
|
0.86 one approach, 0.74 both approaches
|
|
LT MAJ
|
0.8
|
Not calibrated
|
1
|
0.42
|
1
|
1
|
|
RT MIN
|
1.36
|
1.56
|
1
|
1
|
1
|
|
SIGHT DISTANCE
|
Not calibrated
|
Not calibrated
|
Not calibrated
|
1
|
1
|
|
HI
|
exp (0.0286)
|
exp (0.0408)
|
Not calibrated
|
Not calibrated
|
|
DRWY1
|
Not calibrated
|
1.09
|
|
MEDIAN
|
0.72
|
1
|
0.52
|
|
COMDRWY1
|
Not calibrated
|
exp (0.0627COMDRWY1)
|
Not calibrated
|
Not calibrated
|
|
HAZRAT1
|
exp (0.1889HAZRAT1)
|
|
PKTRUCK
|
exp (-0.0253PKTRUCK)
|
exp (-0.0520PKTRUCK)
|
|
PKTURN
|
exp(0.0254PKTURN)
|
Not calibrated
|
|
PKLEFT1
|
Not calibrated
|
exp (0.0523PKLEF)
|
|
SDR2
|
Not calibrated
|
|
LIGHT
|
0.67
|
|
HEI2
|
exp (-0.0284HEI2)
|
A sensitivity analysis was performed to examine the estimated effect on safety of the AMFs derived from the full models and regression base models. The sensitivity analysis
applies each AMF to the base model estimate for various levels of AADT.
The predicted TOTAL and INJURY accident frequencies per year for each AMF derived from the full models and regression base models are presented in tables 188 through 195.
Type I TOTAL Accidents
The AMFs derived for TOTAL accidents for Type I intersections are HI1, right-turn lanes on major, right-turn lane on minor, and left-turn lanes on major roads. The sensitivity test results for these AMFs are presented in tables 188 through 191.
Table 188. Sensitivity of Safety to HI1 for Type I TOTAL Accidents Per Year
|
Major Road AADT (veh/day)
|
Minor Road AADT (veh/day)
|
HI1
|
|
0
|
5
|
10
|
20
|
|
400
|
50
|
0.088
|
0.101
|
0.115
|
0.150
|
|
100
|
0.113
|
0.129
|
0.147
|
0.191
|
|
400
|
0.185
|
0.211
|
0.240
|
0.312
|
|
1,000
|
100
|
0.204
|
0.233
|
0.265
|
0.345
|
|
500
|
0.361
|
0.411
|
0.469
|
0.610
|
|
1,000
|
0.461
|
0.526
|
0.600
|
0.780
|
|
3,000
|
100
|
0.414
|
0.472
|
0.539
|
0.701
|
|
500
|
0.732
|
0.835
|
0.952
|
1.239
|
|
1,000
|
0.936
|
1.067
|
1.217
|
1.583
|
|
3,000
|
1.380
|
1.574
|
1.796
|
2.336
|
|
5,000
|
100
|
0.576
|
0.656
|
0.749
|
0.974
|
|
500
|
1.017
|
1.160
|
1.324
|
1.722
|
|
1,000
|
1.300
|
1.483
|
1.692
|
2.200
|
|
3,000
|
1.919
|
2.188
|
2.496
|
3.247
|
|
5,000
|
2.299
|
2.622
|
2.990
|
3.890
|
|
10,000
|
100
|
0.900
|
1.026
|
1.170
|
1.522
|
|
500
|
1.590
|
1.814
|
2.069
|
2.691
|
|
1,000
|
2.033
|
2.318
|
2.644
|
3.440
|
|
3,000
|
2.999
|
3.421
|
3.901
|
5.075
|
|
5,000
|
3.594
|
4.099
|
4.675
|
6.081
|
|
10,000
|
4.593
|
5.238
|
5.975
|
7.772
|
Note: Group B AADT base model was used.
The AMF for HI1 was derived from full models.
Table 189. Sensitivity of Safety to RT MAJ for Type I TOTAL Accidents Per Year
|
Major Road AADT (veh/day)
|
Minor Road AADT (veh/day)
|
RT MAJ
|
|
No Right-Turn Lane on Major Road
|
Presence of Right-Turn Lane on Major Road
|
|
400
|
50
|
0.088
|
0.078
|
|
100
|
0.113
|
0.099
|
|
400
|
0.185
|
0.162
|
|
1,000
|
100
|
0.204
|
0.180
|
|
500
|
0.361
|
0.317
|
|
1,000
|
0.461
|
0.406
|
|
3,000
|
100
|
0.414
|
0.364
|
|
500
|
0.732
|
0.644
|
|
1,000
|
0.936
|
0.823
|
|
3,000
|
1.380
|
1.215
|
|
5,000
|
100
|
0.576
|
0.506
|
|
500
|
1.017
|
0.895
|
|
1,000
|
1.300
|
1.144
|
|
3,000
|
1.919
|
1.688
|
|
5,000
|
2.299
|
2.023
|
|
10,000
|
100
|
0.900
|
0.792
|
|
500
|
1.590
|
1.400
|
|
1,000
|
2.033
|
1.789
|
|
3,000
|
2.999
|
2.639
|
|
5,000
|
3.594
|
3.162
|
|
10,000
|
4.593
|
4.042
|
Note: Group B AADT base model was used.
The AMF for RT MAJ was derived from full models.
Table 190. Sensitivity of Safety to RT MIN for Type I TOTAL Accidents Per Year
|
Major Road AADT (veh/day)
|
Minor Road AADT (veh/day)
|
RT MIN
|
|
No Right-Turn Lane on Minor Road
|
Presence of Right-Turn Lane on Minor Road
|
|
A
|
B
|
|
400
|
50
|
0.088
|
0.119
|
0.131
|
|
100
|
0.113
|
0.153
|
0.167
|
|
400
|
0.185
|
0.249
|
0.273
|
|
1,000
|
100
|
0.204
|
0.275
|
0.302
|
|
500
|
0.361
|
0.487
|
0.534
|
|
1,000
|
0.461
|
0.622
|
0.682
|
|
3,000
|
100
|
0.414
|
0.559
|
0.613
|
|
500
|
0.732
|
0.988
|
1.083
|
|
1,000
|
0.936
|
1.263
|
1.385
|
|
3,000
|
1.380
|
1.864
|
2.043
|
|
5,000
|
100
|
0.576
|
0.777
|
0.852
|
|
500
|
1.017
|
1.374
|
1.506
|
|
1,000
|
1.300
|
1.756
|
1.925
|
|
3,000
|
1.919
|
2.590
|
2.839
|
|
5,000
|
2.299
|
3.103
|
3.402
|
|
10,000
|
100
|
0.900
|
1.215
|
1.332
|
|
500
|
1.590
|
2.147
|
2.354
|
|
1,000
|
2.033
|
2.744
|
3.099
|
|
3,000
|
2.999
|
4.049
|
4.439
|
|
5,000
|
3.594
|
4.851
|
5.319
|
|
10,000
|
4.593
|
6.200
|
6.798
|
Note: Group B AADT base model was used.
A: AMF derived from full models.
B: AMF derived from regression models.
Table 191. Sensitivity of Safety to LT MAJ for Type I TOTAL Accidents Per Year
|
Major Road AADT (veh/day)
|
Minor Road AADT (veh/day)
|
LT MAJ
|
|
No Left-Turn Lane on Major Road
|
Presence of Left-Turn Lane on Major Road
|
|
400
|
50
|
0.088
|
0.073
|
|
100
|
0.113
|
0.093
|
|
400
|
0.185
|
0.151
|
|
1,000
|
100
|
0.204
|
0.167
|
|
500
|
0.361
|
0.296
|
|
1,000
|
0.461
|
0.378
|
|
3,000
|
100
|
0.414
|
0.340
|
|
500
|
0.732
|
0.600
|
|
1,000
|
0.936
|
0.767
|
|
3,000
|
1.380
|
1.132
|
|
5,000
|
100
|
0.576
|
0.472
|
|
500
|
1.017
|
0.834
|
|
1,000
|
1.300
|
1.066
|
|
3,000
|
1.919
|
1.573
|
|
5,000
|
2.299
|
1.885
|
|
10,000
|
100
|
0.900
|
0.738
|
|
500
|
1.590
|
1.304
|
|
1,000
|
2.033
|
1.667
|
|
3,000
|
2.999
|
2.459
|
|
5,000
|
3.594
|
2.947
|
|
10,000
|
4.593
|
3.766
|
Note: Group B AADT base model was used.
The AMF for LT MAJ was derived from full models.
Type I INJURY Accidents
The AMFs derived for INJURY accidents for Type I intersections are HI1, right-turn lane on major, right-turn lanes on minor, and left-turn lanes on major roads. The sensitivity test results for these AMFs are presented in tables 192 through 195.
Table 192. Sensitivity of Safety to HI1 for Type I INJURY Accidents Per Year
|
Major Road AADT (veh/day)
|
Minor Road AADT (veh/day)
|
HI1
|
|
0
|
5
|
10
|
20
|
|
400
|
50
|
0.036
|
0.042
|
0.048
|
0.064
|
|
100
|
0.046
|
0.053
|
0.061
|
0.081
|
|
400
|
0.073
|
0.084
|
0.097
|
0.129
|
|
1,000
|
100
|
0.082
|
0.095
|
0.109
|
0.145
|
|
500
|
0.142
|
0.163
|
0.188
|
0.251
|
|
1,000
|
0.179
|
0.206
|
0.238
|
0.317
|
|
3,000
|
100
|
0.166
|
0.192
|
0.221
|
0.295
|
|
500
|
0.287
|
0.331
|
0.382
|
0.508
|
|
1,000
|
0.362
|
0.418
|
0.482
|
0.642
|
|
3,000
|
0.526
|
0.606
|
0.700
|
0.931
|
|
5,000
|
100
|
0.231
|
0.266
|
0.307
|
0.409
|
|
500
|
0.398
|
0.459
|
0.530
|
0.705
|
|
1,000
|
0.503
|
0.581
|
0.670
|
0.892
|
|
3,000
|
0.730
|
0.842
|
0.971
|
1.293
|
|
5,000
|
0.867
|
1.001
|
1.154
|
1.537
|
|
10,000
|
100
|
0.361
|
0.416
|
0.480
|
0.639
|
|
500
|
0.621
|
0.717
|
0.827
|
1.101
|
|
1,000
|
0.786
|
0.906
|
1.046
|
1.392
|
|
3,000
|
1.139
|
1.314
|
1.516
|
2.018
|
|
5,000
|
1.354
|
1.562
|
1.802
|
2.399
|
|
10,000
|
1.712
|
1.975
|
2.278
|
3.033
|
Note: Group B AADT base model was used.
The AMF for HI1 was derived from full models.
Table 193. Sensitivity of Safety to RT MAJ for Type I INJURY Accidents Per Year
|
Major Road AADT (veh/day)
|
Minor Road AADT (veh/day)
|
RT MAJ
|
|
No Right-Turn Lane on Major Road
|
Presence of Right-Turn Lane on Major Road
|
|
400
|
50
|
0.036
|
0.031
|
|
100
|
0.046
|
0.040
|
|
400
|
0.073
|
0.063
|
|
1,000
|
100
|
0.082
|
0.071
|
|
500
|
0.142
|
0.123
|
|
1,000
|
0.179
|
0.156
|
|
3,000
|
100
|
0.166
|
0.145
|
|
500
|
0.287
|
0.249
|
|
1,000
|
0.362
|
0.315
|
|
3,000
|
0.526
|
0.457
|
|
5,000
|
100
|
0.231
|
0.201
|
|
500
|
0.398
|
0.346
|
|
1,000
|
0.503
|
0.438
|
|
3,000
|
0.730
|
0.635
|
|
5,000
|
0.867
|
0.755
|
|
10,000
|
100
|
0.361
|
0.314
|
|
500
|
0.621
|
0.541
|
|
1,000
|
0.786
|
0.684
|
|
3,000
|
1.139
|
0.991
|
|
5,000
|
1.354
|
1.178
|
|
10,000
|
1.712
|
1.489
|
Note: Group B AADT base model was used.
The AMF for RT MAJ was derived from full models.
Table 194. Sensitivity of Safety to RT MIN for Type I INJURY Accidents Per Year
|
Major Road AADT (veh/day)
|
Minor Road AADT (veh/day)
|
RT MIN
|
|
No right-turn lane on minor road
|
Presence of right-turn lane on minor road
|
|
A
|
B
|
|
400
|
50
|
0.036
|
0.049
|
0.056
|
|
100
|
0.046
|
0.062
|
0.071
|
|
400
|
0.073
|
0.099
|
0.114
|
|
1,000
|
100
|
0.082
|
0.112
|
0.128
|
|
500
|
0.142
|
0.192
|
0.221
|
|
1,000
|
0.179
|
0.243
|
0.279
|
|
3,000
|
100
|
0.166
|
0.226
|
0.260
|
|
500
|
0.287
|
0.390
|
0.447
|
|
1,000
|
0.362
|
0.493
|
0.565
|
|
3,000
|
0.526
|
0.715
|
0.820
|
|
5,000
|
100
|
0.231
|
0.314
|
0.360
|
|
500
|
0.398
|
0.541
|
0.621
|
|
1,000
|
0.503
|
0.684
|
0.785
|
|
3,000
|
0.730
|
0.992
|
1.138
|
|
5,000
|
0.867
|
1.180
|
1.353
|
|
10,000
|
100
|
0.361
|
0.490
|
0.563
|
|
500
|
0.621
|
0.845
|
0.970
|
|
1,000
|
0.786
|
1.068
|
1.226
|
|
3,000
|
1.139
|
1.549
|
1.777
|
|
5,000
|
1.354
|
1.841
|
2.112
|
|
10,000
|
1.712
|
2.328
|
2.670
|
Note: Group B AADT base model was used.
A: AMF derived from full models.
B: AMF derived from regression models.
Table 195. Sensitivity of Safety to LT MAJ for Type I INJURY Accidents Per Year
|
Major Road AADT (veh/day)
|
Minor Road AADT (veh/day)
|
LT MAJ
|
|
No Left-Turn Lane on Major Road
|
Presence of Left-Turn Lane on Major Road
|
|
400
|
50
|
0.036
|
0.029
|
|
100
|
0.046
|
0.036
|
|
400
|
0.073
|
0.058
|
|
1,000
|
100
|
0.082
|
0.066
|
|
500
|
0.142
|
0.113
|
|
1,000
|
0.179
|
0.143
|
|
3,000
|
100
|
0.166
|
0.133
|
|
500
|
0.287
|
0.229
|
|
1,000
|
0.362
|
0.290
|
|
3,000
|
0.526
|
0.420
|
|
5,000
|
100
|
0.231
|
0.185
|
|
500
|
0.398
|
0.318
|
|
1,000
|
0.503
|
0.403
|
|
3,000
|
0.730
|
0.584
|
|
5,000
|
0.867
|
0.694
|
|
10,000
|
100
|
0.361
|
0.288
|
|
500
|
0.621
|
0.497
|
|
1,000
|
0.786
|
0.629
|
|
3,000
|
1.139
|
0.911
|
|
5,000
|
1.354
|
1.083
|
|
10,000
|
1.712
|
1.369
|
Note: Group B AADT base model was used.
The AMF for LT MAJ was derived from full models.
The predicted TOTAL and INJURY accident frequencies per year for each AMF derived from the full models and regression base models are presented in tables 196 through 204.
Type II TOTAL Accidents
The AMFs derived for TOTAL accidents for Type II intersections are ND, right-turn lanes on major, left-turn lanes on major, and median on major roads. The sensitivity test results for these AMFs are presented in tables 196 through 199.
Table 196. Sensitivity of Safety to DRWY1 for Type II TOTAL Accidents Per Year
|
Major Road AADT (veh/day)
|
Minor Road AADT (veh/day)
|
DRWY1
|
|
0
|
3
|
5
|
|
400
|
50
|
0.056
|
0.064
|
0.072
|
|
100
|
0.082
|
0.093
|
0.105
|
|
400
|
0.175
|
0.198
|
0.223
|
|
1,000
|
100
|
0.158
|
0.179
|
0.202
|
|
500
|
0.380
|
0.429
|
0.485
|
|
1,000
|
0.554
|
0.626
|
0.707
|
|
3,000
|
100
|
0.346
|
0.391
|
0.442
|
|
500
|
0.831
|
0.939
|
1.061
|
|
1,000
|
1.212
|
1.369
|
1.548
|
|
3,000
|
2.204
|
2.491
|
2.815
|
|
5,000
|
100
|
0.498
|
0.563
|
0.636
|
|
500
|
1.196
|
1.351
|
1.527
|
|
1,000
|
1.744
|
1.971
|
2.227
|
|
3,000
|
3.173
|
3.585
|
4.051
|
|
5,000
|
4.190
|
4.735
|
5.350
|
|
10,000
|
100
|
0.816
|
0.922
|
1.042
|
|
500
|
1.960
|
2.215
|
2.503
|
|
1,000
|
2.859
|
3.230
|
3.650
|
|
3,000
|
5.200
|
5.876
|
6.639
|
|
5,000
|
6.867
|
7.760
|
8.769
|
|
10,000
|
10.016
|
11.318
|
12.789
|
Note: Group B AADT base model was used.
The AMF for DRWY1 was derived from full models.
Table 197. Sensitivity of Safety to RT MAJ for Type II TOTAL Accidents Per Year
|
Major Road AADT (veh/day)
|
Minor Road AADT (veh/day)
|
RT MAJ
|
|
No Right-Turn Lane on Major Road
|
Presence of Right-Turn Lane on Major Road
|
|
A
|
B
|
C
|
|
400
|
50
|
0.056
|
0.067
|
0.049
|
0.040
|
|
100
|
0.082
|
0.098
|
0.071
|
0.058
|
|
400
|
0.175
|
0.208
|
0.151
|
0.124
|
|
1,000
|
100
|
0.158
|
0.188
|
0.136
|
0.112
|
|
500
|
0.380
|
0.452
|
0.327
|
0.270
|
|
1,000
|
0.554
|
0.659
|
0.476
|
0.393
|
|
3,000
|
100
|
0.346
|
0.412
|
0.297
|
0.246
|
|
500
|
0.831
|
0.989
|
0.715
|
0.590
|
|
1,000
|
1.212
|
1.442
|
1.042
|
0.860
|
|
3,000
|
2.204
|
2.623
|
1.896
|
1.565
|
|
5,000
|
100
|
0.498
|
0.592
|
0.428
|
0.353
|
|
500
|
1.196
|
1.423
|
1.028
|
0.849
|
|
1,000
|
1.744
|
2.076
|
1.500
|
1.238
|
|
3,000
|
3.173
|
3.775
|
2.728
|
2.252
|
|
5,000
|
4.190
|
4.986
|
3.603
|
2.975
|
|
10,000
|
100
|
0.816
|
0.971
|
0.702
|
0.579
|
|
500
|
1.960
|
2.332
|
1.686
|
1.392
|
|
1,000
|
2.859
|
3.402
|
2.459
|
2.030
|
|
3,000
|
5.200
|
6.188
|
4.472
|
3.692
|
|
5,000
|
6.867
|
8.172
|
5.906
|
4.876
|
|
10,000
|
10.016
|
11.919
|
8.614
|
7.111
|
Note: Group B AADT base model was used.
A: AMF derived from full models, Group A data.
B: AMF derived from full models, Group B data.
C: AMF derived from regression models
Table 198. Sensitivity of Safety to LT MAJ for Type II TOTAL Accidents Per Year
|
Major Road AADT (veh/day)
|
Minor Road AADT (veh/day)
|
LT MAJ
|
|
No Left-Turn Lane on Major Road
|
Presence of Left-Turn Lane on Major Road
|
|
400
|
50
|
0.056
|
0.040 |
|
100
|
0.082
|
0.058
|
|
400
|
0.175
|
0.124
|
|
1,000
|
100
|
0.158
|
0.112
|
|
500
|
0.380
|
0.270
|
|
1,000
|
0.554
|
0.393
|
|
3,000
|
100
|
0.346
|
0.246
|
|
500
|
0.831
|
0.590
|
|
1,000
|
1.212
|
0.860
|
|
3,000
|
2.204
|
1.565
|
|
5,000
|
100
|
0.498
|
0.353
|
|
500
|
1.196
|
0.8449
|
|
1,000
|
1.744
|
1.238
|
|
3,000
|
3.173
|
2.252
|
|
5,000
|
4.190
|
2.975
|
|
10,000
|
100
|
0.816
|
0.579
|
|
500
|
1.960
|
1.392
|
|
1,000
|
2.859
|
2.030
|
|
3,000
|
5.200
|
3.692
|
|
5,000
|
6.867
|
4.876
|
|
10,000
|
10.016
|
7.111
|
Note: Group B AADT base model was used.
The AMF for LT MAJ was derived from regression models.
Table 199. Sensitivity of Safety to MEDIAN for Type II TOTAL Accidents Per Year
|
Major Road AADT (veh/day)
|
Minor Road AADT (veh/day)
|
MEDIAN
|
|
No Median on Major Road
|
Presence of Median on Major Road
|
|
400
|
50
|
0.056
|
0.043
|
|
100
|
0.082
|
0.063
|
|
400
|
0.175
|
0.135
|
|
1,000
|
100
|
0.158
|
0.122
|
|
500
|
0.380
|
0.292
|
|
1,000
|
0.554
|
0.426
|
|
3,000
|
100
|
0.346
|
0.266
|
|
500
|
0.831
|
0.640
|
|
1,000
|
1.212
|
0.933
|
|
3,000
|
2.204
|
1.697
|
|
5,000
|
100
|
0.498
|
0.383
|
|
500
|
1.196
|
0.921
|
|
1,000
|
1.744
|
1.343
|
|
3,000
|
3.173
|
2.443
|
|
5,000
|
4.190
|
3.226
|
|
10,000
|
100
|
0.816
|
0.628
|
|
500
|
1.960
|
1.509
|
|
1,000
|
2.859
|
2.201
|
|
3,000
|
5.200
|
4.004
|
|
5,000
|
6.867
|
5.288
|
|
10,000
|
10.016
|
7.712
|
Note: Group B AADT base model was used.
The AMF for MEDIAN was derived from regression models.
Type II INJURY Accidents
The AMFs derived for INJURY accidents for Type II intersections are HI1, DRWY1, right-turn lanes on major, left-turn lanes on major, and median on major roads. The sensitivity test results for these AMFs are presented in tables 200 through 204.
Table 200. Sensitivity of Safety to HI1 for Type II INJURY Accidents Per Year
|
Major Road AADT (veh/day)
|
Minor Road AADT (veh/day)
|
HI1
|
|
0
|
5
|
10
|
20
|
|
400
|
50
|
0.033
|
0.040
|
0.049
|
0.074
|
|
100
|
0.049
|
0.060
|
0.073
|
0.110
|
|
400
|
0.107
|
0.131
|
0.161
|
0.242
|
|
1,000
|
100
|
0.087
|
0.106
|
0.130
|
0.196
|
|
500
|
0.216
|
0.265
|
0.325
|
0.489
|
|
1,000
|
0.321
|
0.394
|
0.483
|
0.726
|
|
3,000
|
100
|
0.173
|
0.212
|
0.259
|
0.390
|
|
500
|
0.431
|
0.529
|
0.649
|
0.975
|
|
1,000
|
0.640
|
0.785
|
0.962
|
1.447
|
|
3,000
|
1.196
|
1.466
|
1.798
|
2.704
|
|
5,000
|
100
|
0.238
|
0.292
|
0.358
|
0.538
|
|
500
|
0.594
|
0.729
|
0.894
|
1.344
|
|
1,000
|
0.882
|
1.082
|
1.326
|
1.995
|
|
3,000
|
1.648
|
2.021
|
2.479
|
3.727
|
|
5,000
|
2.204
|
2.703
|
3.315
|
4.985
|
|
10,000
|
100
|
0.368
|
0.451
|
0.553
|
0.831
|
|
500
|
0.919
|
1.127
|
1.382
|
2.078
|
|
1,000
|
1.363
|
1.672
|
2.050
|
3.083
|
|
3,000
|
2.548
|
3.124
|
3.831
|
5.761
|
|
5,000
|
3.407
|
4.178
|
5.124
|
7.705
|
|
10,000
|
5.055
|
6.199
|
7.602
|
11.433
|
Note: Group B AADT base model was used.
The AMF for HI1 was derived from full models.
Table 201. Sensitivity of Safety to DRWY1 for Type II INJURY Accidents Per Year
|
Major Road AADT (veh/day)
|
Minor Road AADT (veh/day)
|
DRWY1
|
|
0
|
3
|
5
|
|
400
|
50
|
0.033
|
0.036
|
0.039
|
|
100
|
0.049
|
0.053
|
0.058
|
|
400
|
0.107
|
0.117
|
0.127
|
|
1,000
|
100
|
0.087
|
0.094
|
0.103
|
|
500
|
0.216
|
0.236
|
0.257
|
|
1,000
|
0.321
|
0.350
|
0.381
|
|
3,000
|
100
|
0.173
|
0.188
|
0.205
|
|
500
|
0.431
|
0.470
|
0.512
|
|
1,000
|
0.640
|
0.697
|
0.760
|
|
3,000
|
1.196
|
1.303
|
1.421
|
|
5,000
|
100
|
0.238
|
0.259
|
0.283
|
|
500
|
0.594
|
0.648
|
0.706
|
|
1,000
|
0.882
|
0.961
|
1.048
|
|
3,000
|
1.648
|
1.797
|
1.958
|
|
5,000
|
2.204
|
2.403
|
2.619
|
|
10,000
|
100
|
0.368
|
0.401
|
0.437
|
|
500
|
0.919
|
1.001
|
1.092
|
|
1,000
|
1.363
|
1.486
|
1.620
|
|
3,000
|
2.548
|
2.777
|
3.027
|
|
5,000
|
3.407
|
3.714
|
4.048
|
|
10,000
|
5.055
|
5.510
|
6.006
|
Note: Group B AADT base model was used.
The AMF for DRWY1 was derived from full models.
Table 202. Sensitivity of Safety to RT MAJ for Type II INJURY Accidents Per Year
|
Major Road AADT (veh/day)
|
Minor Road AADT (veh/day)
|
RT MAJ
|
|
No Right-Turn Lane on Major Road
|
Presence of Right-Turn Lane on Major Road
|
|
400
|
50
|
0.033
|
0.028
|
|
100
|
0.049
|
0.041
|
|
400
|
0.107
|
0.091
|
|
1,000
|
100
|
0.087
|
0.074
|
|
500
|
0.216
|
0.184
|
|
1,000
|
0.321
|
0.273
|
|
3,000
|
100
|
0.173
|
0.147
|
|
500
|
0.431
|
0.367
|
|
1,000
|
0.640
|
0.544
|
|
3,000
|
1.196
|
1.016
|
|
5,000
|
100
|
0.238
|
0.202
|
|
500
|
0.594
|
0.505
|
|
1,000
|
0.882
|
0.750
|
|
3,000
|
1.648
|
1.401
|
|
5,000
|
2.204
|
1.874
|
|
10,000
|
100
|
0.368
|
0.312
|
|
500
|
0.919
|
0.781
|
|
1,000
|
1.363
|
1.159
|
|
3,000
|
2.548
|
2.165
|
|
5,000
|
3.407
|
2.896
|
|
10,000
|
5.055
|
4.297
|
Note: Group B AADT base model was used.
The AMF for RT MAJ was derived from full models.
Table 203. Sensitivity of Safety to LT MAJ for Type II INJURY Accidents Per Year
|
Major Road AADT (veh/day)
|
Minor Road AADT (veh/day)
|
LT MAJ
|
|
No Left-Turn Lane on Major Road
|
Presence of Left-Turn Lane on Major Road
|
|
400
|
50
|
0.033
|
0.014
|
|
100
|
0.049
|
0.020
|
|
400
|
0.107
|
0.045
|
|
1,000
|
100
|
0.087
|
0.036
|
|
500
|
0.216
|
0.091
|
|
1,000
|
0.321
|
0.135
|
|
3,000
|
100
|
0.173
|
0.072
|
|
500
|
0.431
|
0.181
|
|
1,000
|
0.640
|
0.269
|
|
3,000
|
1.196
|
0.502
|
|
5,000
|
100
|
0.238
|
0.100
|
|
500
|
0.594
|
0.250
|
|
1,000
|
0.882
|
0.370
|
|
3,000
|
1.648
|
0.692
|
|
5,000
|
2.204
|
0.926
|
|
10,000
|
100
|
0.368
|
0.154
|
|
500
|
0.919
|
0.386
|
|
1,000
|
1.363
|
0.573
|
|
3,000
|
2.548
|
1.070
|
|
5,000
|
3.407
|
1.431
|
|
10,000
|
5.055
|
2.123
|
Note: Group B AADT base model was used.
The AMF for LT MAJ was derived from regression models.
Table 204. Sensitivity of Safety to MEDIAN for Type II INJURY Accidents Per Year
|
Major Road AADT (veh/day)
|
Minor Road AADT (veh/day)
|
MEDIAN
|
|
No Median on Major Road
|
Presence of Median on Major Road
|
|
A
|
B
|
|
400
|
50
|
0.033
|
0.024
|
0.017
|
|
100
|
0.049
|
0.035
|
0.025
|
|
400
|
0.107
|
0.077
|
0.056
|
|
1,000
|
100
|
0.087
|
0.062
|
0.045
|
|
500
|
0.216
|
0.156
|
0.112
|
|
1,000
|
0.321
|
0.231
|
0.167
|
|
3,000
|
100
|
0.173
|
0.124
|
0.090
|
|
500
|
0.431
|
0.311
|
0.224
|
|
1,000
|
0.640
|
0.461
|
0.333
|
|
3,000
|
1.196
|
0.861
|
0.622
|
|
5,000
|
100
|
0.238
|
0.171
|
0.124
|
|
500
|
0.594
|
0.428
|
0.309
|
|
1,000
|
0.882
|
0.635
|
0.459
|
|
3,000
|
1.648
|
1.187
|
0.857
|
|
5,000
|
2.204
|
1.587
|
1.146
|
|
10,000
|
100
|
0.368
|
0.265
|
0.191
|
|
500
|
0.919
|
0.662
|
0.478
|
|
1,000
|
1.363
|
0.981
|
0.709
|
|
3,000
|
2.548
|
1.834
|
1.325
|
|
5,000
|
3.407
|
2.453
|
1.772
|
|
10,000
|
5.055
|
3.640
|
2.629
|
Note: Group B AADT base model was used.
A: AMF derived from full models.
B: AMF derived from regression models.
The predicted TOTAL and INJURY accident frequencies per year for each AMF derived from the full models and regression base models are presented in tables 205 through 215.
Type III TOTAL Accidents
The AMFs derived for TOTAL accidents for Type III intersections are intersection SKEW angle, commercial driveways on major road, vertical curves on major road, median width on major road, painted median type on major road, and major road left-turn lane. The sensitivity test results for these AMFs are presented in tables 205 through 210.
Table 205. Sensitivity of Safety to Skew Angles for Type III TOTAL Accidents Per Year
|
Major Road AADT (veh/day)
|
Minor Road AADT (veh/day)
|
SKEW Angle (degrees)
|
|
A
|
B
|
A
|
B
|
A
|
B
|
A
|
B
|
A
|
B
|
|
0
|
10
|
15
|
30
|
45
|
|
400
|
50
|
0.01
|
0.01
|
0.01
|
0.01
|
0.01
|
0.01
|
0.01
|
0.01
|
0.02
|
0.01
|
|
100
|
0.01
|
0.01
|
0.01
|
0.01
|
0.01
|
0.01
|
0.02
|
0.02
|
0.02
|
0.02
|
|
400
|
0.02
|
0.02
|
0.02
|
0.02
|
0.02
|
0.02
|
0.02
|
0.02
|
0.03
|
0.02
|
|
1,000
|
100
|
0.03
|
0.03
|
0.04
|
0.04
|
0.04
|
0.04
|
0.05
|
0.04
|
0.05
|
0.05
|
|
500
|
0.05
|
0.05
|
0.06
|
0.06
|
0.06
|
0.06
|
0.07
|
0.07
|
0.08
|
0.07
|
|
1,000
|
0.06
|
0.06
|
0.07
|
0.07
|
0.07
|
0.07
|
0.08
|
0.08
|
0.09
|
0.09
|
|
3,000
|
100
|
0.11
|
0.11
|
0.12
|
0.13
|
0.13
|
0.13
|
0.15
|
0.15
|
0.17
|
0.16
|
|
500
|
0.17
|
0.17
|
0.18
|
0.19
|
0.19
|
0.20
|
0.23
|
0.22
|
0.26
|
0.24
|
|
1,000
|
0.20
|
0.20
|
0.22
|
0.23
|
0.23
|
0.24
|
0.27
|
0.26
|
0.31
|
0.28
|
|
3,000
|
0.26
|
0.26
|
0.29
|
0.30
|
0.31
|
0.31
|
0.36
|
0.35
|
0.41
|
0.37
|
|
5,000
|
100
|
0.19
|
0.19
|
0.21
|
0.22
|
0.23
|
0.23
|
0.26
|
0.26
|
0.30
|
0.28
|
|
500
|
0.29
|
0.29
|
0.32
|
0.33
|
0.34
|
0.35
|
0.39
|
0.39
|
0.46
|
0.41
|
|
1,000
|
0.35
|
0.35
|
0.38
|
0.40
|
0.40
|
0.42
|
0.47
|
0.46
|
0.55
|
0.49
|
|
3,000
|
0.46
|
0.46
|
0.51
|
0.52
|
0.53
|
0.55
|
0.62
|
0.61
|
0.72
|
0.65
|
|
5,000
|
0.52
|
0.52
|
0.58
|
0.60
|
0.61
|
0.63
|
0.71
|
0.70
|
0.82
|
0.74
|
|
10,000
|
100
|
0.41
|
0.41
|
0.46
|
0.47
|
0.48
|
0.49
|
0.56
|
0.55
|
0.65
|
0.59
|
|
500
|
0.62
|
0.62
|
0.69
|
0.71
|
0.72
|
0.74
|
0.84
|
0.83
|
0.98
|
0.89
|
|
1,000
|
0.74
|
0.74
|
0.82
|
0.85
|
0.86
|
0.89
|
1.00
|
0.99
|
1.17
|
1.06
|
|
3,000
|
0.98
|
0.98
|
1.09
|
1.12
|
1.14
|
1.17
|
1.33
|
1.30
|
1.55
|
1.40
|
|
5,000
|
1.12
|
1.12
|
1.24
|
1.27
|
1.30
|
1.34
|
1.51
|
1.48
|
1.76
|
1.59
|
|
10,000
|
1.33
|
1.33
|
1.47
|
1.52
|
1.55
|
1.59
|
1.80
|
1.77
|
2.10
|
1.90
|
Note: Group B AADT base model was used.
A: AMF derived from full models.
B: AMF derived from regression models.
Table 206. Sensitivity of Safety to Commercial Driveways on Major Road forType III TOTAL Accidents Per Year
|
Major Road AADT (veh/day)
|
Minor Road AADT (veh/day)
|
Commercial Driveways on Major Road (density)
|
|
0
|
5
|
10
|
15
|
|
400
|
50
|
0.01
|
0.01
|
0.02
|
0.03
|
|
100
|
0.01
|
0.02
|
0.02
|
0.03
|
|
400
|
0.02
|
0.02
|
0.03
|
0.05
|
|
1,000
|
100
|
0.03
|
0.05
|
0.07
|
0.09
|
|
500
|
0.05
|
0.07
|
0.10
|
0.14
|
|
1,000
|
0.06
|
0.08
|
0.12
|
0.17
|
|
3,000
|
100
|
0.11
|
0.16
|
0.22
|
0.31
|
|
500
|
0.17
|
0.23
|
0.33
|
0.46
|
|
1,000
|
0.20
|
0.28
|
0.39
|
0.55
|
|
3,000
|
0.26
|
0.37
|
0.52
|
0.73
|
|
5,000
|
100
|
0.19
|
0.27
|
0.38
|
0.54
|
|
500
|
0.29
|
0.41
|
0.58
|
0.81
|
|
1,000
|
0.35
|
0.49
|
0.69
|
0.96
|
|
3,000
|
0.46
|
0.65
|
0.91
|
1.28
|
|
5,000
|
0.52
|
0.74
|
1.03
|
1.45
|
|
10,000
|
100
|
0.41
|
0.58
|
0.82
|
1.15
|
|
500
|
0.62
|
0.87
|
1.23
|
1.73
|
|
1,000
|
0.74
|
1.04
|
1.47
|
2.06
|
|
3,000
|
0.98
|
1.38
|
1.94
|
2.72
|
|
5,000
|
1.12
|
1.57
|
2.21
|
3.10
|
|
10,000
|
1.33
|
1.87
|
2.63
|
3.70
|
Note: Group B AADT base model was used.
The AMF for CD on major road was derived from full models.
Table 207. Sensitivity of Safety to Vertical Curves on Major Road (VEI1) for Type III TOTAL Accidents Per Year
|
Major Road AADT (veh/day)
|
Minor Road AADT (veh/day)
|
VEI1
|
|
0
|
3
|
5
|
10
|
|
400
|
50
|
0.01
|
0.01
|
0.02
|
0.03
|
|
100
|
0.01
|
0.02
|
0.02
|
0.04
|
|
400
|
0.02
|
0.02
|
0.03
|
0.05
|
|
1,000
|
100
|
0.03
|
0.05
|
0.06
|
0.10
|
|
500
|
0.05
|
0.07
|
0.09
|
0.15
|
|
1,000
|
0.06
|
0.08
|
0.10
|
0.18
|
|
3,000
|
100
|
0.11
|
0.15
|
0.19
|
0.33
|
|
500
|
0.17
|
0.23
|
0.29
|
0.49
|
|
1,000
|
0.20
|
0.27
|
0.34
|
0.59
|
|
3,000
|
0.26
|
0.36
|
0.45
|
0.77
|
|
5,000
|
100
|
0.19
|
0.27
|
0.33
|
0.57
|
|
500
|
0.29
|
0.40
|
0.50
|
0.86
|
|
1,000
|
0.35
|
0.48
|
0.60
|
1.02
|
|
3,000
|
0.46
|
0.64
|
0.79
|
1.35
|
|
5,000
|
0.52
|
0.72
|
0.90
|
1.54
|
|
10,000
|
100
|
0.41
|
0.57
|
0.71
|
1.22
|
|
500
|
0.62
|
0.86
|
1.07
|
1.83
|
|
1,000
|
0.74
|
1.03
|
1.27
|
2.19
|
|
3,000
|
0.98
|
1.36
|
1.68
|
2.89
|
|
5,000
|
1.12
|
1.54
|
1.92
|
3.29
|
|
10,000
|
1.33
|
1.84
|
2.29
|
3.93
|
Note: Group B AADT base model was used.
The AMF for VEI1 was derived from full models.
Table 208. Sensitivity of Safety to Median Width on Major Road (MEDWIDTH1) for Type III TOTAL Accidents Per Year
|
Major Road AADT (veh/day)
|
Minor Road AADT (veh/day)
|
MEDWIDHT1
|
|
0
|
6
|
12
|
20
|
|
400
|
50
|
0.01
|
0.01
|
0.01
|
0.01
|
|
100
|
0.01
|
0.01
|
0.01
|
0.01
|
|
400
|
0.02
|
0.02
|
0.02
|
0.01
|
|
1,000
|
100
|
0.03
|
0.03
|
0.03
|
0.03
|
|
500
|
0.05
|
0.05
|
0.04
|
0.04
|
|
1,000
|
0.06
|
0.06
|
0.05
|
0.05
|
|
3,000
|
100
|
0.11
|
0.10
|
0.10
|
0.09
|
|
500
|
0.17
|
0.16
|
0.15
|
0.13
|
|
1,000
|
0.20
|
0.19
|
0.17
|
0.16
|
|
3,000
|
0.26
|
0.25
|
0.23
|
0.21
|
|
5,000
|
100
|
0.19
|
0.18
|
0.17
|
0.16
|
|
500
|
0.29
|
0.27
|
0.26
|
0.24
|
|
1,000
|
0.35
|
0.33
|
0.31
|
0.28
|
|
3,000
|
0.46
|
0.43
|
0.40
|
0.37
|
|
5,000
|
0.52
|
0.49
|
0.46
|
0.42
|
|
10,000
|
100
|
0.41
|
0.39
|
0.36
|
0.33
|
|
500
|
0.62
|
0.58
|
0.55
|
0.50
|
|
1,000
|
0.74
|
0.70
|
0.65
|
0.60
|
|
3,000
|
0.98
|
0.92
|
0.86
|
0.79
|
|
5,000
|
1.12
|
1.05
|
0.98
|
0.90
|
|
10,000
|
1.33
|
1.25
|
1.17
|
1.08
|
Note: Group B AADT base model was used.
The AMF for MEDWIDTH1 was derived from full models.
Table 209. Sensitivity of Safety to Painted Median Type on Major Road (MEDTYPE1) for Type III TOTAL Accidents Per Year
|
Major Road AADT (veh/day)
|
Minor Road AADT (veh/day)
|
Median Type on Major Road
|
|
No Median
|
Painted Median
|
|
400
|
50
|
0.01
|
0.01
|
|
100
|
0.01
|
0.01
|
|
400
|
0.02
|
0.01
|
|
1,000
|
100
|
0.03
|
0.02
|
|
500
|
0.05
|
0.04
|
|
1,000
|
0.06
|
0.04
|
|
3,000
|
100
|
0.11
|
0.08
|
|
500
|
0.17
|
0.12
|
|
1,000
|
0.20
|
0.15
|
|
3,000
|
0.26
|
0.19
|
|
5,000
|
100
|
0.19
|
0.14
|
|
500
|
0.29
|
0.21
|
|
1,000
|
0.35
|
0.25
|
|
3,000
|
0.46
|
0.34
|
|
5,000
|
0.52
|
0.38
|
|
10,000
|
100
|
0.41
|
0.30
|
|
500
|
0.62
|
0.45
|
|
1,000
|
0.74
|
0.54
|
|
3,000
|
0.98
|
0.72
|
|
5,000
|
1.12
|
0.82
|
|
10,000
|
1.33
|
0.97
|
Note: Group B AADT base model was used.
The AMF for MEDTYPE1 was derived from full models.
Table 210. Sensitivity of Safety to Major Road Left-Turn Lane for Type III TOTAL Accidents Per Year
|
Major Road AADT (veh/day)
|
Minor Road AADT (veh/day)
|
Major Road Left-Turn Lane
|
|
No Left-Turn Lane
|
One Left-Turn Lane
|
|
400
|
50
|
0.01
|
0.01
|
|
100
|
0.01
|
0.01
|
|
400
|
0.02
|
0.01
|
|
1,000
|
100
|
0.03
|
0.02
|
|
500
|
0.05
|
0.04
|
|
1,000
|
0.06
|
0.04
|
|
3,000
|
100
|
0.11
|
0.08
|
|
500
|
0.17
|
0.12
|
|
1,000
|
0.20
|
0.14
|
|
3,000
|
0.26
|
0.19
|
|
5,000
|
100
|
0.19
|
0.14
|
|
500
|
0.29
|
0.21
|
|
1,000
|
0.35
|
0.25
|
|
3,000
|
0.46
|
0.33
|
|
5,000
|
0.52
|
0.37
|
|
10,000
|
100
|
0.41
|
0.29
|
|
500
|
0.62
|
0.44
|
|
1,000
|
0.74
|
0.53
|
|
3,000
|
0.98
|
0.70
|
|
5,000
|
1.12
|
0.79
|
|
10,000
|
1.33
|
0.95
|
Note: Group B AADT base model was used.
The AMF for Major Road Left-Turn Lane was derived from regression models.
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