The table below gives the critical design elements along with references to the location of the AASHTO criteria in the 1994 Green Book, "A Policy on Geometric Design of Highway and Streets 1994." If any of the 12 critical design elements will not be met on a project then a design exception request needs to be submitted to the appropriate agency.
| CRITICAL ELEMENTS | FREEWAYS | ARTERIALS | COLLECTORS | ||
| RURAL | URBAN | RURAL | URBAN | ||
| Design Speed | 555-556, 559 Table VIII-1 |
484 | 513 | 461 Table VI-1 |
471-472 |
| Lane Width | 557 | 488 Table VII-2 |
515-516 521-522 |
464-465 Table VI-4 |
473-474 |
| Shoulder Width | 557 | 488 Table VII-2 |
520 | 464-465 Table VI-4 |
473-474 |
| Horizontal Alignment | 141 | 485 | 514 | 463 | 472 |
| Vertical Alignment | 226 559 |
490, 499-500 Table VII-3 |
513-514 | 226 & 462 Table VI-2B |
472 |
| Grades | 558 | 486 Table VII-1 |
513-514 Table VII-4 |
463 Table VI-3 |
472 Table VI-3 |
| Stopping-Sight Distance | 117 & 120 | 485 | 513 | 461-462 Table VI-2A |
472 |
| Cross Slopes | 557 | 487 | 514-515 | 464 | 472 |
| Superelevation | 558 | 486 | 515 | 464 | 473 |
| Structural Capacity | 558-559 | 487 | Not Specified | 466-467 Tables VI-5, VI-6 |
Not Specified |
| Vertical Clearance | 559 | 487 | 515 | 468 | 477 |
| Bridge Width | 558-559 | 487 | 524 | 466-467 Tables VI-5, VI-6 |
477 |
Last modified: April 18, 2001
copyright © 2001 by Mary Beth
Page Title: Roadway Design Standards
URL: http://www.oocities.org/marybeth0000/dsgnstd.html
marybeth0000@yahoo.com