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From page 21... ... 21 Passenger cars are currently the primary design vehicle for freeway mainline ramp terminals. However, many freeway mainline ramp terminals serve a considerable amount of truck traffic and, given the difference in performance capabilities between passenger cars and trucks, a primary question to be answered is whether freeway mainline ramp terminal design should consider the performance characteristics of heavy vehicles. Read the entire page →
From page 22... ... 22 In the analysis, ramps were grouped into seven configurations: • Diamond, • Parclo loop, • Free-flow loop, • Outer connection, • Direct or semi-direct connection, • Button hook, scissor, and slip ramps, and • Others. Figure 4 illustrates the typical ramp configurations included in the seven groupings used in this analysis. Read the entire page →
From page 23... ... 23 ramps were of the diamond type. Table 6 shows the overall mileage of the ramps and roadway segments included the analysis. Read the entire page →
From page 24... ... Location Ramp configuration Grand total Diamond Parclo loop Free-flow loop Outer connection Direct or semidirect connection Button hook, scissor, and slip ramps Others Total Truck Total Truck Total Truck Total Truck Total Truck Total Truck Total Truck Total Truck Truck percent Entrance ramps Accel. lane 28 1 3 1 3 0 7 0 16 1 2 0 35 3 94 6 6.38 Freeway mainline 2,808 297 445 38 196 11 308 42 355 36 541 50 1,895 208 6,548 682 10.42 Ramp proper 189 6 13 1 55 7 23 1 45 3 28 2 527 23 880 43 4.89 Total 3,025 304 461 40 254 18 338 43 416 40 571 52 2,457 234 7,522 731 9.72 Exit ramps Decel. Read the entire page →
From page 25... ... 25 for direct or semi-direct connections. It is interesting that the entrance ramp configuration with the greatest proportion of crashes occurring on the ramp proper is the freeflow loop ramp (22 percent of total crashes and 39 percent of truck crashes) Read the entire page →
From page 26... ... 26 ramps (12.64 percent) Read the entire page →
From page 27... ... Location Single-vehicle crashes Multiple-vehicle crashes Totals C o l l i s i o n w i t h p a r k e d m o t o r v e h i c l e C o l l i s i o n w i t h r a i l r o a d t r a i n C o l l i s i o n w i t h b i c y c l i s t C o l l i s i o n w i t h p e d e s t r i a n C o l l i s i o n w i t h a n i m a l C o l l i s i o n w i t h f i x e d o b j e c t C o l l i s i o n w i t h o t h e r o b j e c t O t h e r s i n g l e v e h i c l e c o l l i s i o n O v e r t u r n F i r e o r e x p l o s i o n O t h e r s i n g l e v e h i c l e n o n c o l l i s i o n R e a r e n d H e a d o n R e a r t o r e a r A n g l e S i d e s w i p e , s a m e d i r e c t i o n S i d e s w i p e , o p p o s i t e d i r e c t i o n O t h e r m u l t i p l e v e h i c l e c o l l i s i o n Entrance ramps Accel. lane 3 0 0 0 0 39 1 0 6 2 4 24 0 0 0 10 0 5 94 Freeway mainline 41 0 0 5 84 1,079 85 16 241 68 62 3,627 3 0 0 919 3 315 6,548 Ramp proper 12 0 1 2 4 514 2 1 101 6 4 153 2 0 0 47 0 31 880 Total 56 0 1 7 88 1,632 88 17 348 76 70 3,804 5 0 0 976 3 351 7,522 Exit ramps Decel. Read the entire page →
From page 28... ... Location Single-vehicle crashes Multiple-vehicle crashes Totals C o l l i s i o n w i t h p a r k e d m o t o r v e h i c l e C o l l i s i o n w i t h r a i l r o a d t r a i n C o l l i s i o n w i t h b i c y c l i s t C o l l i s i o n w i t h p e d e s t r i a n C o l l i s i o n w i t h a n i m a l C o l l i s i o n w i t h f i x e d o b j e c t C o l l i s i o n w i t h o t h e r o b j e c t O t h e r s i n g l e v e h i c l e c o l l i s i o n O v e r t u r n F i r e o r e x p l o s i o n O t h e r s i n g l e v e h i c l e n o n c o l l i s i o n R e a r e n d H e a d o n R e a r t o r e a r A n g l e S i d e s w i p e , s a m e d i r e c t i o n S i d e s w i p e , o p p o s i t e d i r e c t i o n O t h e r m u l t i p l e v e h i c l e c o l l i s i o n Entrance ramps Accel. lane 1 0 0 0 0 2 0 0 0 1 0 1 0 0 0 1 0 0 6 Freeway mainline 6 0 0 0 3 48 12 2 8 3 25 260 0 0 0 248 0 67 682 Ramp proper 2 0 0 0 0 9 0 0 11 0 2 8 0 0 0 5 0 6 43 Total 9 0 0 0 3 59 12 2 19 4 27 269 0 0 0 254 0 73 731 Exit ramps Decel. Read the entire page →
From page 29... ... 29 entrance ramps, and sideswipe, same-direction crashes along the mainline were also common at freeway-ramp terminal entrance ramps (34 percent of truck crashes at entrance ramps) Read the entire page →
From page 30... ... Area Single-vehicle crashes Multiple-vehicle crashes T otal C o l l i s i o n w i t h p a r k e d m o t o r v e h i c l e C o l l i s i o n w i t h r a i l r o a d t r a i n C o l l i s i o n w i t h b i c y c l i s t C o l l i s i o n w i t h p e d e s t r i a n C o l l i s i o n w i t h a n i m a l C o l l i s i o n w i t h f i x e d o b j e c t C o l l i s i o n w i t h o t h e r o b j e c t O t h e r s i n g l e v e h i c l e c o l l i s i o n O v e r t u r n F i r e o r e x p l o s i o n O t h e r s i n g l e v e h i c l e n o n c o l l i s i o n R e a r e n d H e a d o n R e a r t o r e a r A n g l e S i d e s w i p e , s a m e d i r e c t i o n S i d e s w i p e , o p p o s i t e d i r e c t i o n O t h e r m u l t i p l e v e h i c l e c o l l i s i o n RT AD T < 500 Entrance ramp s Acceleration lane 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 1 Free wa y mainline 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Ramp proper 1 0 0 0 0 3 0 0 1 0 1 0 0 0 0 0 0 2 8 To tal 1 0 0 0 0 3 0 0 1 1 1 0 0 0 0 0 0 2 9 Exit ramps Deceleration lane 0 0 0 0 0 0 0 0 1 0 0 1 0 0 0 1 0 0 3 Free wa y mainline 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Ramp proper 1 0 0 0 0 7 0 0 3 2 1 3 0 0 0 1 0 1 1 9 To tal 1 0 0 0 0 7 0 0 4 2 1 4 0 0 0 2 0 1 2 2 500 < R TA DT < 1,000 Entrance ramp s Acceleration lane 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 1 0 0 2 Free wa y mainline 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Ramp proper 1 0 0 0 0 3 0 0 2 0 0 4 0 0 0 2 0 1 13 To tal 1 0 0 0 0 4 0 0 2 0 0 4 0 0 0 3 0 1 15 Exit ramps Deceleration lane 0 0 0 0 0 1 0 0 1 0 0 1 0 0 0 0 0 1 4 Free wa y mainline 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Ramp proper 1 0 0 0 0 4 0 0 8 1 2 2 0 0 0 2 0 0 20 To tal 1 0 0 0 0 5 0 0 9 1 2 3 0 0 0 2 0 1 24 RT AD T > 1,000 Entrance ramp s Acceleration lane 1 0 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 0 0 0 3 Free wa y mainline 6 0 0 0 3 48 12 2 8 3 2 5 260 0 0 0 248 0 6 7 682 Ramp proper 0 0 0 0 0 3 0 0 8 0 1 4 0 0 0 3 0 3 2 2 To tal 7 0 0 0 3 5 2 12 2 16 3 2 6 265 0 0 0 251 0 7 0 707 Exit ramps Deceleration lane 0 0 0 1 0 0 0 0 1 7 0 0 0 5 0 0 1 4 Free wa y mainline 4 0 0 1 0 13 6 1 3 3 3 112 0 0 1 100 0 2 0 267 Ramp proper 3 0 0 0 0 3 0 0 3 0 1 7 0 0 0 7 0 2 2 6 To tal 7 0 0 1 0 1 7 6 1 6 3 5 126 0 0 1 112 0 2 2 307 Table 12. Truck crashes by crash type and RTADT. Read the entire page →
From page 31... ... Area Ramp configuration Total Diamond Parclo loop Free-flow loop Outer connection Direct or semi-direct connection Button hook, scissor, and slip ramps Others Total Truck Total Truck Total Truck Total Truck Total Truck Total Truck Total Truck Total Truck Entrance ramps Acceleration lane 0 .09 0 .03 0 .13 0 .40 0 .16 0 .00 0 .21 0 .00 0 .37 0 .26 0 .08 0 .00 0 .29 0 .26 0 .16 0 .10 Freeway mainline 0 .60 0 .63 1 .27 1 .11 1 .14 0 .59 0 .69 0 .96 0 .82 0 .95 1 .43 1 .45 1 .09 1 .36 0 .80 0 .86 Ramp proper 0.85 0 .22 1 .41 0 .94 1 .96 2 .08 0 .93 0 .34 1 .54 1 .32 1 .80 1 .49 3 .94 1 .83 1 .90 0 .85 Total 0.58 0 .57 1 .21 1 .06 1 .16 0 .76 0 .67 0 .85 0 .82 0 .91 1 .35 1 .36 1 .23 1 .32 0 .81 0 .80 Exit ramps Deceleration lane 0 .37 0 .12 0 .35 0 .00 0 .55 0 .00 0 .74 0 .87 0 .96 1 .50 0 .14 0 .00 1 .03 1 .00 0 .68 0 .57 Freeway mainline 0 .32 0 .36 0 .44 0 .68 1 .25 1 .80 0 .62 0 .47 0 .73 0 .91 0 .65 0 .75 0 .96 1 .22 0 .59 0 .67 Ramp proper 1.00 0 .79 1 .73 1 .95 2 .72 2 .09 1 .68 1 .23 1 .44 1 .22 1 .87 1 .56 1 .28 1 .04 1 .30 1 .03 Total 0.40 0 .40 0 .53 0 .75 1 .45 1 .67 0 .78 0 .63 0 .90 1 .04 0 .74 0 .81 1 .00 1 .19 0 .67 0 .70 Table 13. Total crash rate (crashes/MVMT) Read the entire page →
From page 32... ... 32 a large truck. This is consistent with the national figures reported by NHTSA indicating that approximately 12 percent of all traffic fatalities involve a large truck. Read the entire page →

From page 21...

... 21 Passenger cars are currently the primary design vehicle for freeway mainline ramp terminals. However, many freeway mainline ramp terminals serve a considerable amount of truck traffic and, given the difference in performance capabilities between passenger cars and trucks, a primary question to be answered is whether freeway mainline ramp terminal design should consider the performance characteristics of heavy vehicles.

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From page 22...

... 22 In the analysis, ramps were grouped into seven configurations: • Diamond, • Parclo loop, • Free-flow loop, • Outer connection, • Direct or semi-direct connection, • Button hook, scissor, and slip ramps, and • Others. Figure 4 illustrates the typical ramp configurations included in the seven groupings used in this analysis.

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From page 23...

... 23 ramps were of the diamond type. Table 6 shows the overall mileage of the ramps and roadway segments included the analysis.

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From page 24...

... Location Ramp configuration Grand total Diamond Parclo loop Free-flow loop Outer connection Direct or semidirect connection Button hook, scissor, and slip ramps Others Total Truck Total Truck Total Truck Total Truck Total Truck Total Truck Total Truck Total Truck Truck percent Entrance ramps Accel. lane 28 1 3 1 3 0 7 0 16 1 2 0 35 3 94 6 6.38 Freeway mainline 2,808 297 445 38 196 11 308 42 355 36 541 50 1,895 208 6,548 682 10.42 Ramp proper 189 6 13 1 55 7 23 1 45 3 28 2 527 23 880 43 4.89 Total 3,025 304 461 40 254 18 338 43 416 40 571 52 2,457 234 7,522 731 9.72 Exit ramps Decel.

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From page 25...

... 25 for direct or semi-direct connections. It is interesting that the entrance ramp configuration with the greatest proportion of crashes occurring on the ramp proper is the freeflow loop ramp (22 percent of total crashes and 39 percent of truck crashes)

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From page 26...

... 26 ramps (12.64 percent)

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From page 27...

... Location Single-vehicle crashes Multiple-vehicle crashes Totals C o l l i s i o n w i t h p a r k e d m o t o r v e h i c l e C o l l i s i o n w i t h r a i l r o a d t r a i n C o l l i s i o n w i t h b i c y c l i s t C o l l i s i o n w i t h p e d e s t r i a n C o l l i s i o n w i t h a n i m a l C o l l i s i o n w i t h f i x e d o b j e c t C o l l i s i o n w i t h o t h e r o b j e c t O t h e r s i n g l e v e h i c l e c o l l i s i o n O v e r t u r n F i r e o r e x p l o s i o n O t h e r s i n g l e v e h i c l e n o n c o l l i s i o n R e a r e n d H e a d o n R e a r t o r e a r A n g l e S i d e s w i p e , s a m e d i r e c t i o n S i d e s w i p e , o p p o s i t e d i r e c t i o n O t h e r m u l t i p l e v e h i c l e c o l l i s i o n Entrance ramps Accel. lane 3 0 0 0 0 39 1 0 6 2 4 24 0 0 0 10 0 5 94 Freeway mainline 41 0 0 5 84 1,079 85 16 241 68 62 3,627 3 0 0 919 3 315 6,548 Ramp proper 12 0 1 2 4 514 2 1 101 6 4 153 2 0 0 47 0 31 880 Total 56 0 1 7 88 1,632 88 17 348 76 70 3,804 5 0 0 976 3 351 7,522 Exit ramps Decel.

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From page 28...

... Location Single-vehicle crashes Multiple-vehicle crashes Totals C o l l i s i o n w i t h p a r k e d m o t o r v e h i c l e C o l l i s i o n w i t h r a i l r o a d t r a i n C o l l i s i o n w i t h b i c y c l i s t C o l l i s i o n w i t h p e d e s t r i a n C o l l i s i o n w i t h a n i m a l C o l l i s i o n w i t h f i x e d o b j e c t C o l l i s i o n w i t h o t h e r o b j e c t O t h e r s i n g l e v e h i c l e c o l l i s i o n O v e r t u r n F i r e o r e x p l o s i o n O t h e r s i n g l e v e h i c l e n o n c o l l i s i o n R e a r e n d H e a d o n R e a r t o r e a r A n g l e S i d e s w i p e , s a m e d i r e c t i o n S i d e s w i p e , o p p o s i t e d i r e c t i o n O t h e r m u l t i p l e v e h i c l e c o l l i s i o n Entrance ramps Accel. lane 1 0 0 0 0 2 0 0 0 1 0 1 0 0 0 1 0 0 6 Freeway mainline 6 0 0 0 3 48 12 2 8 3 25 260 0 0 0 248 0 67 682 Ramp proper 2 0 0 0 0 9 0 0 11 0 2 8 0 0 0 5 0 6 43 Total 9 0 0 0 3 59 12 2 19 4 27 269 0 0 0 254 0 73 731 Exit ramps Decel.

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From page 29...

... 29 entrance ramps, and sideswipe, same-direction crashes along the mainline were also common at freeway-ramp terminal entrance ramps (34 percent of truck crashes at entrance ramps)

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From page 30...

... Area Single-vehicle crashes Multiple-vehicle crashes T otal C o l l i s i o n w i t h p a r k e d m o t o r v e h i c l e C o l l i s i o n w i t h r a i l r o a d t r a i n C o l l i s i o n w i t h b i c y c l i s t C o l l i s i o n w i t h p e d e s t r i a n C o l l i s i o n w i t h a n i m a l C o l l i s i o n w i t h f i x e d o b j e c t C o l l i s i o n w i t h o t h e r o b j e c t O t h e r s i n g l e v e h i c l e c o l l i s i o n O v e r t u r n F i r e o r e x p l o s i o n O t h e r s i n g l e v e h i c l e n o n c o l l i s i o n R e a r e n d H e a d o n R e a r t o r e a r A n g l e S i d e s w i p e , s a m e d i r e c t i o n S i d e s w i p e , o p p o s i t e d i r e c t i o n O t h e r m u l t i p l e v e h i c l e c o l l i s i o n RT AD T < 500 Entrance ramp s Acceleration lane 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 1 Free wa y mainline 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Ramp proper 1 0 0 0 0 3 0 0 1 0 1 0 0 0 0 0 0 2 8 To tal 1 0 0 0 0 3 0 0 1 1 1 0 0 0 0 0 0 2 9 Exit ramps Deceleration lane 0 0 0 0 0 0 0 0 1 0 0 1 0 0 0 1 0 0 3 Free wa y mainline 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Ramp proper 1 0 0 0 0 7 0 0 3 2 1 3 0 0 0 1 0 1 1 9 To tal 1 0 0 0 0 7 0 0 4 2 1 4 0 0 0 2 0 1 2 2 500 < R TA DT < 1,000 Entrance ramp s Acceleration lane 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 1 0 0 2 Free wa y mainline 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Ramp proper 1 0 0 0 0 3 0 0 2 0 0 4 0 0 0 2 0 1 13 To tal 1 0 0 0 0 4 0 0 2 0 0 4 0 0 0 3 0 1 15 Exit ramps Deceleration lane 0 0 0 0 0 1 0 0 1 0 0 1 0 0 0 0 0 1 4 Free wa y mainline 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Ramp proper 1 0 0 0 0 4 0 0 8 1 2 2 0 0 0 2 0 0 20 To tal 1 0 0 0 0 5 0 0 9 1 2 3 0 0 0 2 0 1 24 RT AD T > 1,000 Entrance ramp s Acceleration lane 1 0 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 0 0 0 3 Free wa y mainline 6 0 0 0 3 48 12 2 8 3 2 5 260 0 0 0 248 0 6 7 682 Ramp proper 0 0 0 0 0 3 0 0 8 0 1 4 0 0 0 3 0 3 2 2 To tal 7 0 0 0 3 5 2 12 2 16 3 2 6 265 0 0 0 251 0 7 0 707 Exit ramps Deceleration lane 0 0 0 1 0 0 0 0 1 7 0 0 0 5 0 0 1 4 Free wa y mainline 4 0 0 1 0 13 6 1 3 3 3 112 0 0 1 100 0 2 0 267 Ramp proper 3 0 0 0 0 3 0 0 3 0 1 7 0 0 0 7 0 2 2 6 To tal 7 0 0 1 0 1 7 6 1 6 3 5 126 0 0 1 112 0 2 2 307 Table 12. Truck crashes by crash type and RTADT.

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From page 31...

... Area Ramp configuration Total Diamond Parclo loop Free-flow loop Outer connection Direct or semi-direct connection Button hook, scissor, and slip ramps Others Total Truck Total Truck Total Truck Total Truck Total Truck Total Truck Total Truck Total Truck Entrance ramps Acceleration lane 0 .09 0 .03 0 .13 0 .40 0 .16 0 .00 0 .21 0 .00 0 .37 0 .26 0 .08 0 .00 0 .29 0 .26 0 .16 0 .10 Freeway mainline 0 .60 0 .63 1 .27 1 .11 1 .14 0 .59 0 .69 0 .96 0 .82 0 .95 1 .43 1 .45 1 .09 1 .36 0 .80 0 .86 Ramp proper 0.85 0 .22 1 .41 0 .94 1 .96 2 .08 0 .93 0 .34 1 .54 1 .32 1 .80 1 .49 3 .94 1 .83 1 .90 0 .85 Total 0.58 0 .57 1 .21 1 .06 1 .16 0 .76 0 .67 0 .85 0 .82 0 .91 1 .35 1 .36 1 .23 1 .32 0 .81 0 .80 Exit ramps Deceleration lane 0 .37 0 .12 0 .35 0 .00 0 .55 0 .00 0 .74 0 .87 0 .96 1 .50 0 .14 0 .00 1 .03 1 .00 0 .68 0 .57 Freeway mainline 0 .32 0 .36 0 .44 0 .68 1 .25 1 .80 0 .62 0 .47 0 .73 0 .91 0 .65 0 .75 0 .96 1 .22 0 .59 0 .67 Ramp proper 1.00 0 .79 1 .73 1 .95 2 .72 2 .09 1 .68 1 .23 1 .44 1 .22 1 .87 1 .56 1 .28 1 .04 1 .30 1 .03 Total 0.40 0 .40 0 .53 0 .75 1 .45 1 .67 0 .78 0 .63 0 .90 1 .04 0 .74 0 .81 1 .00 1 .19 0 .67 0 .70 Table 13. Total crash rate (crashes/MVMT)

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From page 32...

... 32 a large truck. This is consistent with the national figures reported by NHTSA indicating that approximately 12 percent of all traffic fatalities involve a large truck.

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Key Terms

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