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Figure 11.
Acceleration lane length at a 5% downgrade
| Design Speed, V (km/h) | Merge Speed, Va (km/h) | Initial Speed V(km/h) | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 40 | 50 | 60 | |||||||||||
| Weight to Power Ratio (kg/kW) | |||||||||||||
| 61 | 67 | 86 | 108 | 61 | 67 | 86 | 108 | 61 | 67 | 86 | 108 | ||
| Acceleration Lane Length (m) | |||||||||||||
| 100 | 74 | 189 | 196 | 207 | 230 | 155 | 160 | 168 | 186 | 108 | 111 | 118 | 128 |
| 120 | 88 | 323 | 334 | 340 | 377 | 277 | 285 | 299 | 334 | 230 | 238 | 249 | 276 |
| 130 | 92 | 360 | 372 | 379 | 424 | 315 | 326 | 340 | 380 | 271 | 279 | 290 | 322 |
Acceleration lane length at a 5% upgrade
| Design Speed, V (km/h) | Merge Speed, Va (km/h) | Initial Speed V(km/h) | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 40 | 50 | 60 | |||||||||||
| Weight to Power Ratio (kg/kW) | |||||||||||||
| 61 | 67 | 86 | 108 | 61 | 67 | 86 | 108 | 61 | 67 | 86 | 108 | ||
| Acceleration Lane Length (m) | |||||||||||||
| 100 | 74 | 1036 | 1863 | NA | NA | 919 | 1763 | NA | NA | 727 | 1575 | NA | NA |
| 120 | 88 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA |
| 130 | 92 | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | NA |
Acceleration lane length at a 3% downgrade
| Design Speed, V (km/h) | Merge Speed, Va (km/h) | Initial Speed V(km/h) | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 40 | 50 | 60 | |||||||||||
| Weight to Power Ratio (kg/kW) | |||||||||||||
| 61 | 67 | 86 | 108 | 61 | 67 | 86 | 108 | 61 | 67 | 86 | 108 | ||
| Acceleration Lane Length (m) | |||||||||||||
| 100 | 74 | 221 | 233 | 271 | 295 | 182 | 191 | 206 | 237 | 127 | 134 | 145 | 163 |
| 120 | 88 | 388 | 404 | 425 | 490 | 335 | 351 | 378 | 438 | 280 | 293 | 315 | 364 |
| 130 | 92 | 435 | 454 | 478 | 553 | 397 | 402 | 432 | 501 | 332 | 343 | 369 | 428 |
Acceleration lane length at level grade
| Design Speed, V (km/h) | Merge Speed, Va (km/h) | Initial Speed V(km/h) | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 40 | 50 | 60 | |||||||||||
| Weight to Power Ratio (kg/kW) | |||||||||||||
| 61 | 67 | 86 | 108 | 61 | 67 | 86 | 108 | 61 | 67 | 86 | 108 | ||
| Acceleration Lane Length (m) | |||||||||||||
| 100 | 74 | 337 | 334 | 390 | 492 | 272 | 286 | 325 | 407 | 205 | 205 | 224 | 268 |
| 120 | 88 | 620 | 649 | 741 | 933 | 537 | 568 | 651 | 844 | 450 | 475 | 547 | 708 |
| 130 | 92 | 701 | 736 | 848 | 1087 | 619 | 661 | 775 | 1002 | 556 | 584 | 659 | 871 |
Acceleration lane length at a 3% upgrade
| Design Speed, V (km/h) | Merge Speed, Va (km/h) | Initial Speed V(km/h) | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 40 | 50 | 60 | |||||||||||
| Weight to Power Ratio (kg/kW) | |||||||||||||
| 61 | 67 | 86 | 108 | 61 | 67 | 86 | 108 | 61 | 67 | 86 | 108 | ||
| Acceleration Lane Length (m) | |||||||||||||
| 100 | 74 | 547 | 630 | 958 | NA | 478 | 520 | 824 | NA | 358 | 430 | 754 | NA |
| 120 | 88 | 1247 | 1582 | NA | NA | 1181 | 1471 | NA | NA | 995 | 1300 | NA | NA |
| 130 | 92 | 1595 | NA | NA | NA | 1490 | NA | NA | NA | 1362 | NA | NA | NA |
Acceleration lane lengths from reviewed sources and proposed acceleration lane lengths from this study
| AASHTO Green Book 2018 | NCHRP Rept. 505- 2003 | This study (108 kg/kW) | Difference Between AASHTO and This Study | ||
|---|---|---|---|---|---|
| Methods | Experimental | TSPM | TruckSim | - | |
| Assumed Initial Speed (km/h) | 35 | 35 | 35 | - | |
| Assumed Merge Speed (km/h) | 74 | 285 | 530 | 526 | 241 |
| 88 | 490 | 994 | 983 | 493 |
Minimum acceleration lane length [1]
| Acceleration Lane Length (m) For Design Speed of Controlling Feature on Ramp V’ (km/h), V’(km/h) | ||||
|---|---|---|---|---|
| 40 | 50 | 60 | ||
| Design Speed, V (km/h) | Merge Speed, Va (km/h) | Average Running Speed at Controlling Feature on Ramp V’a (km/h) | ||
| 35 | 42 | 51 | ||
| 100 | 74 | 285 | 255 | 205 |
| 120 | 88 | 490 | 460 | 410 |
| 130 | 92 | 530 | 520 | 500 |
Adjusted Grade Factors [1]
| Design Speed, V (km/h) | Ratio of Length on Grade to Length on Level for Design Speed of Turning Curve (km/h) | |||
|---|---|---|---|---|
| 40 | 50 | 60 | All Speeds | |
| 3 to 4% Upgrade | 3 to 4% Downgrade | |||
| 100 | 1.5 | 1.6 | 1.7 | 0.6 |
| 120 | 1.5 | 1.6 | 1.7 | 0.6 |
| 130 | 1.6 | 1.7 | 1.8 | 0.6 |
| 5 to 6% Upgrade | 5 to 6% Downgrade | |||
| 100 | 1.7 | 1.9 | 2.2 | 0.5 |
| 120 | 2.15 | 2.35 | 2.8 | 0.5 |
| 130 | 2.3 | 2.5 | 3 | 0.5 |
Results in assumption 4
| Variable | Tolerance | VIF |
|---|---|---|
| Grade | 0.902 | 1.109 |
| Weight to Power ratio | 0.941 | 1.063 |
| Merge Speed to Initial Speed | 0.759 | 1.318 |
Comparison of acceleration rate in the AASHTO and this study
| Design Speed (km/h) | Merge Speed (km/h) | Design Speed (km/h) | |||||
|---|---|---|---|---|---|---|---|
| 40 | 50 | 60 | |||||
| Initial Speed (km/h) | |||||||
| 35 | 42 | 51 | |||||
| Acceleration Rate for 108 kg/kW Truck at Level Grade (km/h/s) | |||||||
| Acceleration Rate (Green book AASHTO) | Acceleration Rate (TruckSim) | Acceleration Rate (Green book AASHTO) | Acceleration Rate (TruckSim) | Acceleration Rate (Green book AASHTO) | Acceleration Rate (TruckSim) | ||
| 100 | 74 | 2.01 | 2.38 | 2.00 | 1.94 | 1.94 | 1.58 |
| 120 | 88 | 1.91 | 2.38 | 1.84 | 1.94 | 1.78 | 1.58 |
Compares maximum weight to power ratios for minimum acceleration length in NCHRP505 and this study at upgrades
| Design Speed (km/h) | Merge Speed (km/h) | Design Speed (km/h) | |||||
|---|---|---|---|---|---|---|---|
| 40 | 50 | 60 | |||||
| Initial Speed (km/h) | |||||||
| 35 | 42 | 51 | |||||
| Maximum weight to power ratios (kg/kW) at 2% and 3% upgrades | |||||||
| NCHRP 505 (TSPM) | This Study (TruckSim) | NCHRP 505 (TSPM) | This Study (TruckSim) | NCHRP 505 (TSPM) | This Study (TruckSim) | ||
| 100 | 74 | 52 | - | 52 | - | 52 | 61 |
| 120 | 88 | 49 | - | 49 | - | 49 | - |
Speeds at the end of the acceleration lane at level grade
| Design Speed, V (km/h) | Merge Speed, Va (km/h) | Initial Speed V(km/h) | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 40 | 50 | 60 | |||||||||||
| Weight to Power Ratio (kg/kW) | |||||||||||||
| 61 | 67 | 86 | 108 | 61 | 67 | 86 | 108 | 61 | 67 | 86 | 108 | ||
| Acceleration Lane Length (m) | |||||||||||||
| 100 | 74 | 70 | 70 | 69 | 64 | 73 | 72 | 70 | 68 | 74 | 74 | 73 | 71 |
| 120 | 88 | 82 | 81 | 78 | 74 | 84 | 83 | 81 | 76 | 86 | 85 | 82 | 80 |
| 130 | 92 | 83 | 82 | 80 | 76 | 87 | 86 | 82 | 79 | 89 | 88 | 86 | 82 |
Specifications of trucks
| Parameters | Tractor | Load | Tractor | Load | Tractor | Load | Tractor | Load |
|---|---|---|---|---|---|---|---|---|
| 61 kg/kW Truck | 67 kg/kW Truck | 86 kg/kW Truck | 108 kg/kW Truck | |||||
| Length (mm) | - | 3000 | - | 3000 | - | 4500 | - | 7500 |
| Width (mm) | 2438 | 1000 | 2438 | 1000 | 2438 | 1750 | 2438 | 2000 |
| Height (mm) | 3200 | 1000 | 3200 | 1000 | 3200 | 1800 | 3200 | 2000 |
| Height of mass center (mm) | 1175 | 1350 | 1175 | 1350 | 1020 | 2150 | 1175 | 2300 |
| Total Mass (kg) | 14165 | 4000 | 14165 | 6000 | 8525 | 20000 | 14165 | 18340 |
| Powertrain (kw) | 300 | - | 300 | - | 330 | - | 300 | - |
Acceleration rates for 61 kg/kW truck at different grades
| Design Speed (km/h) | Merge Speed (km/h) | Initial Speed (km/h) | ||
|---|---|---|---|---|
| 40 | 50 | 60 | ||
| Acceleration Rate for 61 kg/kW Truck at Level Grade (km/h/s) | ||||
| 100 | 74 | 3.46 | 2.83 | 2.10 |
| 120 | 88 | 3.46 | 2.81 | 2.30 |
| 130 | 92 | 3.46 | 2.81 | 2.30 |
Comparison of maximum weight to power ratios for minimum acceleration length in NCHRP505 and this study
| Design Speed (km/h) | Merge Speed (km/h) | Design Speed (km/h) | |||||
|---|---|---|---|---|---|---|---|
| 40 | 50 | 60 | |||||
| Initial Speed (km/h) | |||||||
| 35 | 42 | 51 | |||||
| Maximum weight to power ratios (kg/kW) at level grade | |||||||
| NCHRP 505 (TSPM) | This Study (TruckSim) | NCHRP 505 (TSPM) | This Study (TruckSim) | NCHRP 505 (TSPM) | This Study (TruckSim) | ||
| 100 | 74 | 70 | 67 | 67 | 67 | 70 | 67 |
| 120 | 88 | 61 | - | 64 | - | 64 | - |