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Manual Notice: 2022-1

From: Marisabel Ramthun, P.E

Manual: Roadway Design Manual

Effective Date: May 11, 2022

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Purpose

The Roadway Design Manual has been revised to update roadway policy in accordance with FHWA guidelines and with comments received from Design Division, other Divisions, and TxDOT’s 25 Districts. As a result, revisions were made to Chapters 1-8 and Appendices A, B, C, D and E. Likewise, all metric units were removed and minor errata type corrections and edits were made throughout the manual.

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Contents

Chapter 1

Section 1: Minor errata type updates.

Section 2: Clarified FHWA role with respect to Design Exception policy.

Section 2: Design Exception, Design Waiver and other associated criteria information has been updated to a tabularized form for ease of use and reference.

Section 2: Table 1-1 was updated to include Bridge Rail requirements.

Section 2: Bicycle facility Design Exception and Design Waiver guidance has been updated and provided in Tables 1-3, and 1-8.

Section 2: Other errata type updates.

Section 3: Changed name of section to Schematic Development.

Section 3: Updated list of items included in Schematic Layout.

Section 3: Updated section on Schematic Approval.

Section 4: Minor errata type updates.

Section 5: Updated list of items included in Preliminary Design process.

Section 6: Minor errata type updates.

Chapter 2

General: Minor errata type edits to Table 2-2, 2-7, and 2-14.

General: Added new Tables 2-10 (Minimum K and L as a Function of A) and 2-11 (Vertical Clearance Requirements).

General: Updated Figure 2-1, 2-2, 2-4, and 2-6 thru 2-10 for better resolution.

General: Added new Figures 2-3 (Diagram Illustrating Components for Determining Horizontal Sight Distance) and 2-5 (Types of Vertical Curves).

Section 1: Changed section 1 Overview to an introduction.

Section 2: Changed section 2 to Functional Classifications.

Section 2: Added Freeways to Functional Classification and added reference to Statewide Planning Map.

Section 3: Changed section 3 to Traffic Characteristics.

Section 3: Added guidance on Traffic Forecast.

Section 3: Added guidance on Computation of DHV and DDHV.

Section 3: Added verbiage on Design Speed.

Section 3: Added guidance on Terrain.

Section 3: Added guidance on Turning Roadways and Intersection Corner Radii.

Section 3: Added guidance on Older Drivers and Older Pedestrians.

Section 4: Added verbiage on Stopping Sight Distance.

Section 4: Changed title of Table 2-1 and some minor errata type edits.

Section 4: Added verbiage for Sight Distance at Under Crossings.

Section 5: Changed section 5 to Horizontal Alignment.

Section 5: Added verbiage for General Considerations for Horizontal Alignment.

Section 5: Added verbiage for Curve Radius.

Section 5: Added verbiage for Superelevation Rate.

Section 5: Changed title of Table 2-3, 2-4, and 2-5, updated values in table and revised footnotes.

Section 5: Updated Table 2-6 by changing values in table.

Section 5: Updated footnote to Table 2-8.

Section 5: Added verbiage for Superelevation Transition Placement.

Section 5: Added verbiage for Superelevation Transition Type.

Section 5: Added verbiage for Sight Distance on Horizontal Curves.

Section 6: Changed section 6 to Vertical Alignment.

Section 6: Added verbiage on Grades.

Section 6: Updated Table 2-9 by changing values in table and revising footnote.

Section 6: Added verbiage on Grade Change without Vertical Curves.

Section 6: Added guidance on Vertical Alignment at Railroad Crossings.

Section 6: Added guidance on Vertical Alignment at Intersections.

Section 6: Added guidance on Vertical Clearance.

Section 7: Changed section 7 to Cross-Sectional Elements.

Section 7: Added verbiage on Pavement Cross Slope.

Section 7: Added verbiage on Median Design.

Section 7: Added guidance on Pavement Taper Lengths.

Section 7: Added verbiage for Curb and Curb with Gutters.

Section 7: Added verbiage for Lateral Offset to Obstructions.

Section 7: Change title of Table 2-12, minor errata type edits, and revised footnotes.

Section 8: Changed section 8 to Drainage Facility Placement.

Section 8: Updated values in Table 2-13.

Section 8: Updated Table 2-15, minor errata type edits and added footnote.

Section 9: Changed section 9 to Roadways Intersecting Department Projects and added verbiage.

Chapter 3

General: Updated Figure 3-1, 3-3 thru 3-5, 3-7, 3-10 thru 3-12, 3-15, 3-20 thru 3-23, 3-25 thru 3-28, for better resolution.

Section 1: Added verbiage in Introduction.

Section 2: Updated Table 3-1 by updating references to other criteria tables and figures and adjusted urban roadway design criteria. Also, revised several footnotes.

Section 2: Added guidance on Raised Medians.

Section 2: Updated Table 3-2 by updating width of TWLTL in table and adding footnote 1.

Section 2: Added guidance on Median Openings.

Section 2: Added new Figure 3-2 on Examples of Left-Turn Lanes with Negative, Zero, and Positive Offset.

Section 2: Added guidance on Berms.

Section 2: Added verbiage on Grade Separations and Interchanges.

Section 2: Added verbiage on Intersections.

Section 2: Added guidance on Speed Change Lanes.

Section 2: Updated Table 3-3 by combining two tables into one table.

Section 2: Updated Table 3-4 by updating values for deceleration length in table, adding footnotes and changing title to include left and right turns lanes.

Section 2: Added new Figure 3-6 on Types of Right Turn Treatments at Intersections.

Section 3: Updated Table 3-5 by updating references to other criteria tables and figures and adjusted suburban roadway design criteria. Also, made updates to footnotes in table.

Section 3: Added verbiage on Right-of-Way Width.

Section 3: Added guidance on Speed Change Lanes.

Section 4: Added verbiage in Overview.

Section 4: Updated Table 3-6 by updating references to other criteria tables and figures for two-lane rural highways.

Section 4: Updated Table 3-7 by updating ADT values in table.

Section 4: Updated Table 3-8 by updating criteria values for travel lanes and shoulders for rural two-lane highways. Also, updated footnotes in table.

Section 4: Added guidance on Passing Sight Distances.

Section 4: Updated Table 3-9 by updating passing sight distance and K values and footnote in table.

Section 4: Added verbiage on Speed Change Lanes.

Section 4: Added new Table 3-10 on Guide for Left-Turn Lane Warrants on Two-Lane Highways in Rural Areas.

Section 4: Added new Figure 3-8 on Suggested Left-Turn Warrants Based on Results from Benefit-Cost Evaluations for Intersections on Two-Lane Highways in Rural Areas.

Section 4: Updated Figure 3-9 by updating guidance on Typical Two-Lane Highway Intersection with Left-Turn Lanes.

Section 5: Added verbiage in Overview.

Section 5: Updated Table 3-11 by updating references to other criteria tables and adjusted multi-lane rural highway design criteria. Also, made updates to footnotes in table.

Section 5: Added guidance on Medians.

Section 5: Added new Figure 3-13 on Left Turn Lanes on Multilane Rural Highways.

Section 5: Updated Table 3-12 by updating deceleration values and removing design turning ADT & storage values. Also, updated footnotes in table.

Section 5: Added new Figure 3-14 on Examples of Tapered and Parallel Acceleration Lanes.

Section 5: Added new Table 3-13 on Minimum Acceleration Lane Lengths for Entrance Terminals with Flat Grades of Less Than 3%.

Section 5: Updated Table 3-14 by updating speed change lane adjustment factors as a function of grade. Also, updated footnote in table.

Section 5: Added verbiage on Intersections.

Section 5: Updated Figure 3-16 by updating guidance on Typical Transitions from Two-Lane to Four-Lane Divided Highways.

Section 6: Added verbiage in Overview.

Section 6: Updated Table 3-15 by updating references to other criteria tables and figures for freeways design criteria.

Section 6: Updated guidance and reorganized section on Access Control.

Section 6: Updated content of Figures 3-17 and 3-18 on access control at entrance and exit ramps with frontage road.

Section 6: Reformatted Table 3-16 on Desirable Spacing between Exit Ramps and Driveways, Side Streets, or Cross Streets.

Section 6: Updated Table 3-17 by updating design speed values for controlled access facilities.

Section 6: Added guidance on Lane Width and Number.

Section 6: Added new Figure 3-19 on Typical Examples of Lane Balance.

Section 6: Updated Table 3-18 by updating values for shoulder width and travel lane width for speed change lanes. Also, updated footnotes in table.

Section 6: Added verbiage on Medians.

Section 6: Added verbiage on Vertical and Clear Zones at Structures.

Section 6: Minor errata type edits to Table 3-19 and footnotes on Design Criteria for Rural Frontage Roads.

Section 6: Added verbiage on Conversion of Frontage Roads from Two-Way to One-Way Operation.

Section 6: Added verbiage on Grade Separations and Interchanges.

Section 6: Updated Figure 3-24 by updating content on Common Diamond Interchanges.

Section 6: Added guidance on Interchange Spacing.

Section 6: Added new Figure 3-33 on Interchange Spacing as Measured between Successive Cross Streets.

Section 6: Added guidance on Auxiliary Lanes.

Section 6: Added verbiage on Ramps and Direct Connectors.

Section 6: Added guidance on Design Speed.

Section 6: Updated Table 3-20 by updating ramp/connector design speed values. Also, updated footnotes in table.

Section 6: Added guidance on Ramp Geometrics.

Section 6: Added guidance on Ramp Gores.

Section 6: Added new Figure 3-34 on Typical Gore Area Characteristics.

Section 6: Added Table 3-21 on Desirable Maximum Grades for Ramps.

Section 6: Added new Figure 3-35 on Typical Ramp Profile Characteristics.

Section 6: Added new Figure 3-36 on Warped Neutral Area for ramps.

Section 6: Added guidance on Cross Section and Cross Slopes.

Section 6: Added guidance on Sight Distance.

Section 6: Added guidance on Ramp Terminal Design.

Section 6: Added new Figure 3-37 on Single-Lane Entrance Ramp Terminals on a Tangent.

Section 6: Added new Figure 3-38 on Entrance Ramp to a Freeway Curving in the Direction of the Ramp.

Section 6: Added new Figure 3-39 on Entrance Ramp to a Freeway Curving Away from the Direction of the Ramp.

Section 6: Added new Figure 3-40 on Entrance Ramp to a Superelevated Freeway Curving Away from the Ramp.

Section 6: Added new Figure 3-41 on Typical Single-Lane Exit Ramp Terminals.

Section 6: Added new Table 3-23 on Minimum Deceleration Lane Lengths for Exit Ramps with Flat Grades of Less Than 3 Percent.

Section 6: Added new Figure 3-42 on Taper-Type Entrance Ramp from a One-Way Frontage Road.

Section 6: Added new Figure 3-43 on Taper-Type Entrance Ramp from a Two-Way Frontage Road.

Section 6: Added guidance on Exit Ramps to Frontage Roads.

Section 6: Added guidance on Ramp Spacing.

Section 6: Added new Figure 3-44 on Arrangements for Successive Ramps.

Section 6: Added guidance on Collector-Distributor Roads.

Section 6: Added guidance on Frontage Road Turnarounds and Intersection Approaches.

Section 6: Added new Figure 3-45 on Typical Diamond Interchange with Frontage Road.

Section 7: Added verbiage on Freeways with High Occupancy Vehicle Treatments.

Section 7: Added Guidance on Peak Hour Lanes.

Section 7: Added Guidance on Tolled Express Lanes.

Chapter 4

General: Updated Figure 4-1, 4-3, 4-4, & 4-5 by updating striping and better resolution.

General: Updated Figure 4-2 for better resolution.

Section 1: Updated Overview.

Section 1: Added guidance that 3R projects must be assessed to determine if bicycle accommodations are required per Chapter 6, Section 4 Bicycle Facilities.

Section 2: Updated Table 4-1 by updating titles to headings, changing a value in the table, and updating footnotes.

Section 2: Updated Table 4-2 by updating titles to headings, adjusting ADT values to prevent overlap, and updating footnotes and superscripts.

Section 2: Updated Table 4-3 by updating descriptions for the design elements and updating footnotes.

Section 2: Added guidance for Design Speed.

Section 2: Added guidance for Lane Widths.

Section 3: Changed title of Section to Designing for Safety.

Section 3: Updated Overview.

Section 3: Added guidance for Safety Design.

Section 3: Added guidance for Guard Fence.

Section 3: Updated guidance for Headwalls.

Section 3: Added guidance for Other Safety Improvements.

Section 4: Updated Table 4-4 by updating titles to headings, adjusting ADT values to prevent overlap, and updating footnotes.

Section 4: Updated Table 4-5 by updating titles to headings, adding design guidance to table for urban frontage roads, and updating footnotes.

Section 5: Updated Overview.

Section 6: Updated Overview.

Section 6: Updated Table 4-6 by adding guidance on design criteria for super 2 highways and updating footnotes.

Section 7: Added new section 7, 3R Project Documentation.

Chapter 5

Section 1: Changed title of Section 1 to Criteria.

Section 1: Added Overview Section.

Section 1: Updated Guidelines section.

Section 1: Added guidance that for 2R projects if bicycle accommodations are provided they must meet Chapter 6, Section 4 Bicycle Facilities.

Section 1: Added guidance for Crash Analysis.

Chapter 6

Section 1: Added verbiage to Overview.

Section 1: Updated guidance on Minimum Structure Widths.

Section 2: Minor errata type edits.

Section 3: Minor errata type edits.

Section 4: Provides updated comprehensive Bicycle Facilities Guidance. This guidance includes General Background, Planning and Context, Elements of Design, Bicycle Facility Types, Intersections and Crossings, and Maintenance and Operations.

The selection of the desired facility type is primarily a function of context (Urbanized, or Rural), vehicular volumes, and vehicular speed. The available Facility Types include: Shared Use Paths (sidepaths), separated bike lanes, buffered bike lanes, bike lanes, bike accessible shoulders, and shared wide outside lanes. The respective design criteria is provided for each of the facility types.

Updated “yield to pedestrians” guidance to “stop and yield to pedestrians” per action of the 2021 State of Texas legislative session.

Updated Off-system bridge guidance.

Provides updated guidance on projects that may be excepted from Bicycle facilities, as well as Design Exception and Design Waiver conditions.

Chapter 7

Section 1: Added verbiage to Overview.

Section 1: Added verbiage to Guardrail.

Section 1: Added guidance on Attenuators in temporary work zone applications.

Section 2: Added verbiage to Overview.

Section 2: Updated Table 7-1 on Type of Fence.

Section 3: Provides updated comprehensive Pedestrian Facilities Guidance. This guidance includes General Background, Elements of Design, Linear Pedestrian Facilities, Curb Ramp Design, Driveway Design Considerations, Intersections and Crossings, Overcrossings and Underpasses, Work Zone Ped. Accommodations, Lightings, On-street parking, Transit Access, Railings Adjacent to Steep Slopes, and additional considerations.

Updated “yield to pedestrians” guidance to “stop and yield to pedestrians” per action of the 2021 State of Texas legislative session.

Section 4: Added verbiage to Overview.

Section 4: Minor errata type edits.

Section 5: Minor errata type edits.

Section 6: Changed title of Section 6 from Emergency Median Openings on Freeways to Emergency Crossovers.

Section 6: Updated Overview by removing references to guidance on Median Openings.

Section 6: Added guidance on Emergency Crossovers under Location.

Section 7: Removed turning templates for design vehicles and added a reference to AASHTO’s Green Book for information on turning paths and turning radii of design vehicles.

Section 7: Updated Table 7-2 by adding guidance for WB-62 & WB-67 design vehicles.

Section 7: Added new Figure 7-46 on Example Pavement Edge Geometry WB-62, 90 Degree Turn.

Section 7: Added guidance on Median U-Turn Movements.

Section 7: Added new Figure 7-47 on AASHTO Minimum Median Widths for U-Turn Crossovers.

Chapter 8

General: Updated Tables 8-2, 8-7, and 8-8 by changing title.

Section 1: Added guidance that 5R projects must be assessed to determine if bicycle accommodations are required per Chapter 6, Section 4 Bicycle Facilities.

Section 2: Re-organized and added verbiage to Overview.

Section 2: Under Shoulders, changed “should” to “must”.

Section 2: Under Pavement Cross Slope, added guidance on highways with three or more lanes inclined in the same direction.

Section 2: Updated Table 8-1 by changing title, updating Brake Reaction Distance, and Stopping Sight Distance.

Section 2: Added guidance on Horizontal Alignment.

Section 2: Updated Table 8-3 by adding Maximum Allowable Friction Factor to title of column.

Section 2: Added guidance on Superelevation.

Section 2: Updated Table 8-4 by updating values and footnotes in table.

Section 2: Updated Table 8-5 by updating values and footnotes in table.

Section 2: Updated Table 8-6 by updating values in table.

Section 3: Updated Table 8-9 by updating titles of headings and updating the footnote.

Section 4: Added guidance on Design Speed.

Section 4: Updated Table 8-10 by changing title of headings, adding guidance on the Lower Range (50%) of Design Speed, and updating footnotes.

Section 4: Updated Table 8-11 by adding a title to the heading of a column and adding values to the table.

Section 4: Added new Table 8-12 to completely replace old table with new values and new formatting.

Section 4: Added new Table 8-13 to completely replace old table with new values and new formatting.

Section 4: Updated Table 8-14 by reformatting, adding values to table and updating footnote.

Appendix A – Longitudinal Barriers

General: “Accident” was replaced with “Crash”.

General: The abbreviation cz means clear zone.

General: Updated Figures A-1, A-4 thru A-7, A-9 thru A-19 for better resolution.

General: Updated Table A-4 for better resolution.

Section 2: Changed deflection range for Semi-rigid barriers from 18-60 inches to 26-60 inches.

Section 2: Added guidance on Barrier Transitions.

Section 2: Added guidance on Special Barrier Applications.

Section 2: Updated Roadside Features, Applications and added footnote #3 to Table A-1.

Section 2: Added clear zone guidance on Gateway Monuments.

Section 2: Added guidance on the removal of metal beam guard fence.

Section 3: Updated Figure A-3 to show projected cross slope/side slope hinge point.

Section 6: Defined equation A-1, L(total)=L(u) + L(p) + L(d).

Section 6: Updated Figure A-8 by removing table.

Section 6: Updated Table A-2 by labeling the equations.

Section 9: Added reference to chapter 7 section 6 for guidance on Emergency Crossovers.

Appendix B – Treatment of Pavement Drop-offs in Work Zones

General: Minor errata updates.

General: Updated Figure B-3 for better resolution.

Section 1: Updated Figure B-1 to show edge of travel lane, Z distance, and edge of dropoff.

Section 1: Added guidance on other factors in the guidelines for construction zone drop-off situations such as Driveways and access, Safety impacts and crash history, and Illumination.

Section 1: Updated Table B-2 for better resolution and made updates to edge condition III to read more clearly.

Section 1: Added guidance on Edge drop-offs greater than 2 inches.

Section 1: Added guidance on 1-2 inch vertical longitudinal joints.

Section 1: Added new Figure B-2.

Section 1: Added reference to the Construction Divisions technical advisory report on Use of Tapered Longitudinal Joints such as the Notched Wedge Joint for additional information.

Appendix C – Driveway Design Guidelines

General: Updated Figures C-1 thru C-11 for better resolution.

General: Deleted old Figures C-12 and C-13 and moved them to Chapter 7.

General: Deleted Figure C-14.

Section 1: Updated Overview.

Section 2: Added definition for Access Connection.

Section 2: Simplified Commercial Driveway definition.

Section 2: Changed “Apron” to “Driveway Apron”.

Section 2: Clarified definition for Effective Turning Radius.

Section 2: Clarified definition for Farm/Ranch Driveway.

Section 2: Clarified definition for Field Driveway.

Section 2: Clarified definitions of Public and Private Driveways.

Section 2: Changed Residential Driveway definition to Private Residential Driveway and clarified definition.

Section 2: Changed Radial Return or Flare Drop Curb definition to Radial Return or Flared Taper Return and clarified definition.

Section 2: Clarified definition for Service Driveway.

Section 2: Removed Shared Driveway definition.

Section 3: Added guidance for General Guidelines for Driveway Design Principles.

Section 3: Updated Table C-1 and added Note.

Section 3: Updated Table C-2 to fix superscripts and added footnotes #3 & #4.

Section 3: Guidance was added for driveways being reconstructed on existing roadway reconstruction projects.

Section 3: Updated Table C-3 to fix superscripts and added footnotes #2 & #3.

Section 4: A reference was added to refer to AASHTO's A Policy on Geometric Design of Highways and Streets and NCHRP Report 659 Guide for the Geometric Design of Driveways for additional information.

Section 4: Guidance was added for Driveway Grades.

Section 4: Updated Table C-4 by adding “Maximum” to title.

Section 4: Updated Table C-5 by removing notes.

Section 5: Added guidance on Two-Way Driveways.

Section 5: Added guidance on One-Way Driveways.

Section 6: Changed title from “Pedestrian Considerations” to “Bicycle and Pedestrian Considerations”.

Section 7: Added guidance on Visibility.

Section 8: Updated References.

Appendix D – Right-Turn Slip Lane Design Guidelines

General: Updated “yield to pedestrians” guidance to “stop and yield to pedestrians” per action of the 2021 State of Texas legislative session.

Section 1: Updated Introduction.

Section 2: Added guidance for Acceleration Lane.

Section 2: Added guidance for Signage and Pavement Markings.

Section 2: Under Rural Design, added guidance for Radius.

Section 3: Added guidance for Yielding to Crossing Pedestrians.

Section 3: Added guidance for Crosswalk Location.

Section 3: Added guidance for Enhancing Visibility of Crossing Pedestrians.

Appendix E – Alternative Intersections and Interchanges

General: Updated “yield to pedestrians” guidance to “stop and yield to pedestrians” per action of the 2021 State of Texas legislative session.

General: Updated Figures E-1 thru E-55 for better resolution.

Section 1: Added guidance for Pedestrian Considerations for Alternative Intersections in Overview.

Section 2: Added guidance on Deflection under Geometric Design.

Section 2: Added guidance on Pedestrian Considerations.

Section 2: Added guidance on Truck Aprons under Considerations.

Section 2: Added guidance on Single-Lane Roundabouts.

Section 2: Added guidance on Multilane Roundabouts.

Section 3: Under Sight Distance, changed “should” to “must”.

Section 4: Deleted old Figure E-31 and moved it to Chapter 7 and renumbered figures accordingly.

Section 7: Updated References.

Instructions

This manual, and all revisions, applies to all transportation project development (all modes), whether developed by the department or by other entities. Due to projects that may be further along in development with current criteria, this manual, and all revisions, will be effective for all projects beginning with the September 2023 Letting, and if project schematic or 30% plans have not been approved by November 1st, 2022. The Districts have the options to use these revisions prior to these dates.

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Contact

Contact the Roadway Design Section Director of the Design Division at (512) 416-2678 with any questions or comments.

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Archives

Past manual notices are available in a pdf archive.

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