CHAPTER 2 GEOMETRIC DESIGN CRITERIA - Tennessee

1 CHAPTER 2 GEOMETRIC DESIGN CRITERIA TDOT ROADWAY DESIGN GUIDELINES CHAPTER 2 GEOMETRIC DESIGN CRITERIA English Revised: 07/08/2022 2-i CHAPTER 2 GEOMETRIC DESIGN CRITERIA Table of Contents INTRODUCTION .. v SECTION 1 CONTROLLING GEOMETRIC DESIGN CRITERIA .. 1 CONTROLLING CRITERIA FOR DESIGN .. 1 HORIZONTAL DESIGN .. 1 HORIZONTAL CURVE RADIUS AND SUPERELEVATION RATES .. 1 TRAVEL, THROUGH, AND TURN LANE WIDTHS .. 3 SHOULDER WIDTHS .. 3 CROSS SLOPES .. 4 VERTICAL DESIGN .. 4 VERTICAL GRADES .. 5 STOPPING SIGHT DISTANCE .. 5 STOPPING SIGHT DISTANCE ON HORIZONTAL AND VERTICAL INTERSECTIONS .. 5 STOPPING SIGHT DISTANCE ON HORIZONTAL AND VERTICAL 5 VERTICAL CLEARANCES FOR BRIDGES.

2 7 DESIGN SPEED .. 8 DESIGN LOADING STRUCTURAL CAPACITY .. 8 DESIGN EXCEPTION REQUESTS .. 8 SECTION 2 NON-CONTROLLING GEOMETRIC DESIGN CRITERIA ..18 NON-CONTROLLING GEOMETRIC DESIGN CRITERIA ..18 PASSING SIGHT DISTANCE ..18 VERTICAL CURVES ..18 ROADSIDE SLOPE DEVELOPMENT ..19 CLEAR ZONE ..20 DESIGN VEHICLE ..21 MULTIMODAL FACILITIES ..22 DESIGN WAIVER REQUESTS ..22 SECTION 6 STRUCTURAL DESIGN ..42 TDOT ROADWAY DESIGN GUIDELINES CHAPTER 2 GEOMETRIC DESIGN CRITERIA English Revised: 07/08/2022 2-ii concrete BOX AND SLAB TYPE CULVERTS AND BRIDGES ..42 TYPE PAVED APRON FOR BOX CULVERT AND BRIDGE OUTLETS.

3 42 concrete BOX AND SLAB TYPE CULVERTS AND BRIDGES IN SHALLOW FILLS ..42 STEEL BAR REINFORCEMENT (ROADWAY) ..48 HAUL ROADS ..48 HAUL ROAD DESIGN CONSIDERATIONS ..48 HAUL ROAD COMPENSATION ..49 HAUL ROAD TYPICAL SECTION ..50 SECTION 7 EARTHWORK DESIGN ..51 EARTHWORK CONSIDERATIONS ..51 EARTHWORK BALANCES ON WIDENING OF EXISTING ROADWAYS ..53 SHRINKAGE AND SWELL FACTORS ..53 GRADING LINE THROUGH SOLID ROCK ..54 PRESPLITTING OF ROCK EXCAVATION ..55 CAPPING ROCK FILLS ..55 EARTHWORK BALANCES IN TOPSOIL REQUIREMENTS FOR EARTHWORK BALANCES ..56 ESTIMATED GRADING QUANTITIES TABULATED BLOCK ..57 GRADING REPORT ..59 SECTION 8 TRUCK CLIMBING LANES ..60 TRUCK CLIMBING LANE DESIGN ..60 LOCATION GUIDELINES.

4 60 CAPACITY ANALYSIS ..61 CRITICAL LENGTH OF GRADE ..61 DESIGN CRITERIA ..67 DOWNGRADES ..71 TRUCK SPEED PROFILE ..71 SECTION 9 RETAINING WALL DESIGN ..76 RETAINING WALLS ..76 TDOT ROADWAY DESIGN GUIDELINES CHAPTER 2 GEOMETRIC DESIGN CRITERIA English Revised: 07/08/2022 2-iii RETAINING WALL SHEET NAMES, NUMBER, AND ORDER IN PLANS ..76 DEVELOP THE RETAINING WALL GEOMETRIC LAYOUT SHEET ..78 RETAINING WALL ASSESSMENT AT SITE REVIEW ..86 GUIDELINES FOR CATEGORY ONE RETAINING WALLS ..87 GUIDELINES FOR CATEGORY TWO RETAINING WALLS ..88 DECORATIVE FACING ON RETAINING WALLS ..89 RETAINING WALL QUANTITIES.

5 89 FUNDING REQUEST AND REVISIONS ..91 CONSTRUCTION FIELD REVIEW, SUBMITTAL, AND REVISIONS ..92 RETAINING WALL FOOTNOTES ON CONSTRUCTION PLANS ..92 RETAINING WALL BARRIER SYSTEM REQUIREMENTS ..93 SECTION 10 - ROUNDABOUT DESIGN ..94 ROUNDABOUT DESIGN PRINCIPLES ..94 ROUNDABOUT DESIGN PROCESS ..97 ROUNDABOUT PLACEMENT CONSIDERATIONS ..97 DETERMINING ROUNDABOUT ROUNDABOUT PROXIMITY TO OTHER INTERSECTIONS ..97 ACCESS MANAGEMENT AND PRIVATE DRIVEWAYS AT ROUNDABOUTS ..98 RAILROAD CROSSINGS AT ROUNDABOUTS .. 101 ROUNDABOUT CORRIDORS .. 101 ROUNDABOUT DESIGN AT INTERCHANGES .. 102 ROUNDABOUT CONGESTION MITIGATION 102 SPLITTER 103 CURBS & ROADWAY TYPICAL SECTIONS .. 104 PAVEMENTS & SURFACE TREATMENTS.

6 104 SECTION 11 ROAD RECONFIGURATION AND ROAD DIET .. 106 ROAD RECONFIGURATION .. 106 ROAD DIET .. 106 ROAD DIET EVALUATION CRITERIA .. 107 ROAD DIET INTERSECTION/CORRIDOR ANALYSIS .. 107 TDOT ROADWAY DESIGN GUIDELINES CHAPTER 2 GEOMETRIC DESIGN CRITERIA English Revised: 07/08/2022 2-iv PLANS DISTRIBUTION AND REVIEW PROCESS .. 108 SECTION 12 DRIVEWAYS .. 109 DRIVEWAYS .. 109 DRIVEWAY TYPICAL SECTION AND DESIGN CRITERIA .. 112 DRIVEWAY VERTICAL CURVES .. 112 DRIVEWAY HORIZONTAL CURVES .. 113 DRIVEWAY CROSS SLOPE .. 113 DRIVEWAY EDGE .. 113 DRIVEWAY APRONS .. 114 DRIVEWAY SIDE DRAINS.

7 114 MULTIMODAL ROADWAY DESIGN IN DRIVEWAYS .. 114 GUIDELINES FOR CONSTRUCTION AND RESURFACING OF DRIVEWAYS ON HIGHWAY PROJECTS .. 114 GENERAL .. 114 RESURFACING .. 115 NEW OR RECONSTRUCTION .. 116 TDOT ROADWAY DESIGN GUIDELINES CHAPTER 2 GEOMETRIC DESIGN CRITERIA English Revised: 07/08/2022 2-v INTRODUCTION ROADWAY DESIGN GUIDELINES AND STANDARD DRAWINGS Roadway DESIGN Guidelines and Standard Drawings have been created to ensure that there is consistency in TDOT projects across the state. The Roadway DESIGN Guidelines and Standard Drawings indicate the current recognized DESIGN standards for new construction or reconstruction of existing highways and shall be utilized while giving due regard to topography, natural conditions, availability of road material, and prevailing traffic conditions.

8 Throughout these guidelines you will see the following terms used. To clarify the meanings intended in this guide by the use of these terms, the following definitions apply: Designer HQ DESIGN , Project Development, or Consultant Designer DESIGN Manager HQ DESIGN , Project Development, or Consultant DESIGN Manager DESIGN Team HQ DESIGN , Project Development, or Consultant DESIGN Technical Report Transportation planning reports ( Transportation Investment Reports (TIR), Transportation Planning Report (TPR)) developed by the Strategic Transportation Investments Division. TDOT ROADWAY DESIGN GUIDELINES CHAPTER 2 GEOMETRIC DESIGN CRITERIA English Revised: 07/08/2022 2-vi This page is left blank intentionally.

9 TDOT ROADWAY DESIGN GUIDELINES CHAPTER 2 GEOMETRIC DESIGN CRITERIA English Revised: 07/08/2022 2-1 SECTION 1 CONTROLLING GEOMETRIC DESIGN CRITERIA CONTROLLING CRITERIA FOR DESIGN The following sections define both horizontal and vertical DESIGN elements including the 10 controlling CRITERIA for DESIGN as defined by the FHWA. The 10 controlling CRITERIA can contribute substantial importance to the operation and safety performance of any highway. A formal written DESIGN exception process should be followed if any of the following CRITERIA cannot be met. See Section DESIGN Exception Requests for further guidance on the process and required form.

10 The 10 CRITERIA are: Horizontal Curve Radius, Superelevation Rate, Lane Width, Shoulder Width, Cross Slopes, Maximum Grade, Stopping Sight Distance, DESIGN Speed, Vertical Clearance, and DESIGN Loading Structural Capacity. HORIZONTAL DESIGN The Horizontal DESIGN consists of the horizontal alignment, typical section, slope development, and roadside DESIGN . The horizontal DESIGN elements are based off of several factors including DESIGN speed, rural or urban setting, type of terrain, AADT, and superelevation. The RD11-TS series - Typical Section and DESIGN CRITERIA and RD11-SE series - Superelevation Details of the Roadway Standard Drawings shall be used to determine the horizontal curve radius, superelevation, lane width, shoulder width, cross slopes, and side slopes.