Roadway Design Manual (RDW)

1 Roadway Design Manual Revised April 2018. 2018 by Texas Department of Transportation (512) 463-8630 all rights reserved Manual Notice 2018-1. From: Camille Thomason, Manual : Roadway Design Manual Effective Date: April 26, 2018. Purpose Roadway Design Manual updates to provide vertical clearance guidance for roadways on the Texas Highway Freight Network (THFN): To provide guidance for the THFN Design Deviation Process;. To provide an explanation and guidance for which projects on the THFN are affected by the new policy;. To provide vertical clearance criteria for applicable projects on the THFN.

2 Contents Table of Contents The addition of the Texas Highway Freight Network (THFN) Design Deviation process to Chapter 1, Section 2. The new addition of Section 8 to Chapter 3. Chapter 1. Contents: The addition of the Texas Highway Freight Network (THFN) Design Deviation process. Section 2: The addition of a new subsection that defines the Texas Highway Freight Network (THFN) Design Deviation process. Chapter 3. Contents: Addition of the Texas Highway Freight Network (THFN) to the Contents. Section 1: Addition of the Texas Highway Freight Network (THFN) to list of Roadway classes, and cross references to Chapter 3, Section 8, and Chapter 1.

3 Addition of reference to the THFN Design Deviation process. Section 8: New Section that explains the application of the Texas Highway Freight Network (THFN) policy. This includes the following: The policy is effective for applicable bridge construction and reconstruction projects on the THFN, Let on September 1, 2020 or later, Designation of a Roadway as being on the latest THFN map maintained by the Transportation Planning and Programming Division (TP&P), The specific vertical clearance Design criteria: ' for applicable bridge structures.

4 ' for pedestrian crossover structures;. ' for overhead signs;. 19' for traffic signals on a designated THFN. Chapter 4. Section 5: Addition of a cross reference to Chapter 3, Section 8. Chapter 6. Section 1: Under the Project Conditions, Addition of a cross reference to Chapter 3, Section 8. Chapter 8. Section 1: In the last paragraph, the addition of a reference to the THFN Design Deviation process. Section 2: Under Vertical Clearance at Structures, the addition of a reference to Chapter 3, Section 8. Contact Contact the Roadway Design Section of the Design Division at (512) 416-2678 with any questions or comments.

5 Archives Past Manual notices are available in a pdf archive. Table of Contents Preface Non-discrimination .. 1-1. Overview .. 1-1. Chapter 1 Design General Section 1 Overview .. 1-2. Application of Design Guidelines .. 1-2. Roadway Design Manual Format .. 1-2. External Reference Documents .. 1-3. Section 2 Design Exceptions, Design Waivers, Design Variances, and Texas Highway Freight Network (THFN) Design Deviations .. 1-5. Overview .. 1-5. Design Exceptions .. 1-5. Design Waivers .. 1-8. Design Variances .. 1-9. Texas Highway Freight Network (THFN) Design Deviations.

6 1-9. Section 3 Schematic Layouts .. 1-10. Overview .. 1-10. Section 4 Additional Access to the Interstate System.. 1-11. Requirements .. 1-11. Section 5 Preliminary Design Submissions .. 1-13. Submissions .. 1-13. Section 6 Maintenance Considerations in Design .. 1-14. Maintenance.. 1-14. Chapter 2 Basic Design Criteria Section 1 Functional Classifications .. 2-2. Overview .. 2-2. Section 2 Traffic Characteristics.. 2-3. Overview .. 2-3. Traffic Volume .. 2-3. Traffic Speed .. 2-5. Turning Roadways and Intersection Corner Radii.

7 2-5. Section 3 Sight Distance .. 2-6. Overview .. 2-6. Stopping Sight Distance .. 2-6. Decision Sight Distance.. 2-7. Roadway Design Manual i txdot 04/2018. Passing Sight Distance.. 2-9. Intersection Sight Distance .. 2-9. Section 4 Horizontal Alignment .. 2-10. Overview .. 2-10. General Considerations for Horizontal Alignment .. 2-10. Curve Radius .. 2-11. Superelevation Rate .. 2-12. Sight Distance on Horizontal Curves .. 2-22. Section 5 Vertical Alignment .. 2-25. Overview .. 2-25. Grades .. 2-25. Vertical Curves .. 2-28.

8 Grade Change Without Vertical Curves .. 2-32. Combination of Vertical and Horizontal Alignment .. 2-32. Section 6 Cross Sectional Elements .. 2-33. Overview .. 2-33. Pavement Cross Slope .. 2-33. Median Design .. 2-34. Lane Widths.. 2-35. Shoulder Widths .. 2-35. Sidewalks and Pedestrian Elements.. 2-36. Curb and Curb and Gutters .. 2-42. Roadside Design .. 2-42. Slopes and Ditches.. 2-43. Lateral Offset to Obstructions .. 2-44. Clear Zone .. 2-45. Section 7 Drainage Facility Placement .. 2-47. Overview .. 2-47. Introduction.

9 2-47. Design Treatment of Cross Drainage Culvert Ends .. 2-48. Parallel Drainage Culverts.. 2-53. Side Ditches .. 2-55. Section 8 Roadways Intersecting Department Projects .. 2-56. Chapter 3 New Location and Reconstruction (4R) Design Criteria Section 1 Overview .. 3-2. Introduction .. 3-2. Section 2 Urban Streets.. 3-3. Overview .. 3-3. Roadway Design Manual ii txdot 04/2018. Level of Service.. 3-3. Basic Design Features .. 3-3. Medians .. 3-6. Median Openings.. 3-8. Borders.. 3-9. Berms.. 3-9. Grade Separations and Interchanges.

10 3-10. Right-of-Way Width .. 3-10. Intersections.. 3-11. Speed Change Lanes .. 3-12. Auxiliary Lanes on Crest Vertical Curves.. 3-17. Horizontal Offsets .. 3-17. Bus Facilities .. 3-18. Bus Streets .. 3-18. Section 3 Suburban Roadways .. 3-19. Overview .. 3-19. Basic Design Features .. 3-19. Access Control.. 3-21. Medians .. 3-22. Median Openings.. 3-23. Speed Change Lanes .. 3-23. Right of Way Width.. 3-23. Horizontal Clearances .. 3-23. Borders.. 3-23. Grade Separations and Interchanges .. 3-23. Intersections.. 3-23. Parking.