HIGHWAY DESIGN MANUAL

HIGHWAY DESIGN MANUAL

Chapter 2

Design Criteria

Revision 96 (Limited Revision)

April 15, 2021

Issued by Engineering Bulletin 21-020 Effective with Design Approval on or after September 1, 2021

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Section

?2.2.7 Culvert Replacement

?2.2.8.1 Safety Projects (formerly ?2.2.7.1 Safety Projects) ?2.3.5 Guidelines for Pedestrian Facilities in the Public Right-of-Way (PROWAG)

Exhibit 2-1a

?2.6.2.1

Exhibit 2-1b Superelevation Rate

?2.6.4 Horizontal Curve Radius Exhibits 2-3, 2-3a, 2-4, 2-4a, 2-5, 2-5a, 2-6, 26a, 2-7, 2-7a, 2-8, 2-8a Exhibit 2-6a

Exhibit 2-7a

?2.7.5.4 Speed Change Lanes

Exhibit 2-9 (Traveled Way Widths for Ramps and Turning Roadways) ?2.7.5.6 CollectorDistributor Roads Exhibit 2-15 Nonstandard Feature Justification

?2.9 References

Changes

New subsection of 2.2 Project Types that describes "Culvert Rehabilitation" and "New and Replacement Culvert" projects

Project type description revised to more clearly define safety projects.

Updated broken links to guidelines on US Access Board website. For consistency with existing text in ?2.6.11, text was modified slightly to state that "PROWAG... establishes is the basis of the Department's standards for accessible pedestrian facilities within highway rights of way."

Flowchart exhibit replaced with table and title revised to "Shoulder Width Considerations for Bicycles"

Section renamed "Lane and Shoulder Width Considerations for Bicycles". Text revised to provide improved guidance for bicycling considerations for the new context classes that were incorporated into Revision 92.

8% added as an allowable superelevation table for "Urban Interstates, Other Freeways, Expressways and Parkways with LOS E or F at ETC" and "Suburban Arterials and Collectors". Note 1 added to table to clarify use of either the 6% superelevation or 8% superelevation. Text revised to clarify how horizontal curve radii are measured.

Exhibit notes revised to refer to Section 2.6.2.1, providing improved guidance for bicycling considerations for the new context classes that were incorporated into Revision 92.

Typo corrected: Minimum Radius Curve (ft) emax = 4% in lower right heading changed to emax = 6%

Typo corrected in Note 8: "Shoulders may be 4 ft. where speeds are < 40 mph."

Text added to allow 15% reduction in acceleration lane length, in certain conditions, based on recommendations in NCHRP 730 Design Guidance for Freeway Mainline Ramp Terminals

Table revised to reflect errata changes to 7th Edition of AASHTO's A Policy on Geometric Design of Highways and Streets, 2018.

Text revised to clarify design criteria and design speeds for collectordistributor roads in relation to the adjacent mainline road.

The forms available on the HDM Chapter 2 webpage have been revised to include additional information in the instructions about design speed and recommended speed. The .pdf version of the form that is available on the HDM Chapter 2 webpage has been revised to add "Left" and "Right" shoulder options and "Other" selections under "1. Type of Feature".

Added NCHRP 730 Design Guidance for Freeway Mainline Ramp Terminals

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TABLE OF CONTENTS

2.1 INTRODUCTION ............................................................................................................................................. 5

2.2 PROJECT TYPES ........................................................................................................................................... 7

2.2.1 2.2.2 2.2.3 2.2.4 2.2.5 2.2.6 2.2.7 2.2.8

Pavement Preventive and Corrective Maintenance .............................................................................. 7 3R - Resurfacing, Restoration and Rehabilitation ................................................................................. 7 Reconstruction and New Construction .................................................................................................. 7 Minor Intersection Reconstruction ......................................................................................................... 8 Major Intersection Reconstruction ......................................................................................................... 8 Bridge Projects ........................................................................................................................................ 8 Culvert Replacement ............................................................................................................................... 9 Additional Information .............................................................................................................................. 9

2.3 DESIGN CRITERIA SOURCES .................................................................................................................... 10

2.3.1 2.3.2 2.3.3 2.3.4 2.3.5 2.3.6 2.3.7

A Policy on Geometric Design of Highways and Streets....................................................................... 10 A Policy on Design Standards, Interstate System ................................................................................. 10 NYSDOT Bridge Manual........................................................................................................................ 10 NYSDOT Guidelines for the Adirondack Park ....................................................................................... 10 Guidelines for Pedestrian Facilities in the Public Right-of-Way (PROWAG) ........................................ 11 Urban Street Design Guide.................................................................................................................... 11 National Cooperative Highway Research Program (NCHRP)............................................................... 11

2.4 FUNCTIONAL CLASSIFICATION OF HIGHWAYS AND CONTEXT CLASSES ........................................ 12

2.4.1 2.4.2

Functional Classification of Highways ................................................................................................... 12 Context Classes..................................................................................................................................... 14

2.5 PROJECT DATA........................................................................................................................................... 22

2.5.1 2.5.2 2.5.3

Traffic ..................................................................................................................................................... 22 Terrain.................................................................................................................................................... 23 Special Routes....................................................................................................................................... 23

2.6 CRITICAL DESIGN ELEMENTS .................................................................................................................. 26

2.6.1 2.6.2 2.6.3 2.6.4 2.6.5 2.6.6 2.6.7 2.6.8 2.6.9 2.6.10 2.6.11

Design Speed ........................................................................................................................................ 26 Lane Width............................................................................................................................................. 27 Shoulder Width ...................................................................................................................................... 30 Horizontal Curve Radius........................................................................................................................ 30 Superelevation ....................................................................................................................................... 31 Stopping Sight Distance (Horizontal and Vertical) ................................................................................ 32 Maximum Grade .................................................................................................................................... 32 Cross Slope ........................................................................................................................................... 32 Vertical Clearance ................................................................................................................................. 33 Design Loading Structural Capacity ...................................................................................................... 33 Americans with Disabilities Act (ADA) Compliance ............................................................................... 33

2.7 STANDARDS ................................................................................................................................................ 34

2.7.1 2.7.2 2.7.3 2.7.4 2.7.5

Interstates and Other Freeways ............................................................................................................ 34 Arterials.................................................................................................................................................. 38 Collector Roads and Streets.................................................................................................................. 50 Local Roads and Streets ....................................................................................................................... 62 Other Roadways .................................................................................................................................... 74

2.8 REQUIREMENTS FOR JUSTIFICATION OF NONSTANDARD FEATURES ............................................. 89

2.8.1 2.8.2 2.8.3

Definition and Procedures ..................................................................................................................... 89 Technical Discrepancies........................................................................................................................ 89 Documentation....................................................................................................................................... 89

2.9 REFERENCES .............................................................................................................................................. 96

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LIST OF EXHIBITS

Exhibit 2-1 Functional Classification & Context Class of Highways - Various Sources .................................... 21 Exhibit 2-1a Shoulder Width Considerations for Bicycles ................................................................................... 29 Exhibit 2-1b Superelevation Rate (Applies to NHS and non-NHS)..................................................................... 31 Exhibit 2-2 Design Criteria for Interstates and Other Freeways........................................................................ 37 Exhibit 2-3 Design Criteria for Non-NHS Rural Arterials ................................................................................... 40 Exhibit 2-3a Design Criteria for NHS Rural Arterials........................................................................................... 43 Exhibit 2-4 Design Criteria for Non-NHS Rural Town, Suburban, Urban, and Urban Core Arterials................ 46 Exhibit 2-4a Design Criteria for NHS Rural Town, Suburban, Urban, and Urban Core Arterials ....................... 49 Exhibit 2-5 Design Criteria for Non-NHS Rural Collectors ................................................................................ 52 Exhibit 2-5a Design Criteria for NHS Rural Collectors ........................................................................................ 55 Exhibit 2-6 Design Criteria for Non-NHS Rural Town, Suburban, Urban, and Urban Core Collectors............. 58 Exhibit 2-6a Design Criteria for NHS Rural Town, Suburban, Urban, and Urban Core Collectors..................... 61 Exhibit 2-7 Design Criteria for Non-NHS Local Rural Roads ............................................................................ 64 Exhibit 2-7a Design Criteria for NHS Local Rural Roads .................................................................................... 67 Exhibit 2-8 Design Criteria for Non-NHS Local Rural Town, Suburban, Urban, and Urban Core Streets........ 70 Exhibit 2-8a Design Criteria for NHS Local Rural Town, Suburban, Urban, and Urban Core Streets................ 73 Exhibit 2-9 Traveled Way Widths for Ramps and Turning Roadways .............................................................. 78 Exhibit 2-10 Design Criteria for Turning Roadways Not Connecting to the NHS ............................................... 79 Exhibit 2-10a Design Criteria for Turning Roadways Connecting to the NHS ...................................................... 79 Exhibit 2-11 Minimum Radii and Superelevation for Low-Speed Non-NHS Urban Highways and Streets ........ 82 Exhibit 2-11a Minimum Radii and Superelevation for Low-Speed NHS Urban Highways and Streets ................ 83 Exhibit 2-12 Minimum Radii for Design Superelevation Rates, Design Speeds, and emax = 4% (Non-NHS) ..... 84 Exhibit 2-12a Minimum Radii for Design Superelevation Rates, Design Speeds, and emax = 4% (NHS) ............. 84 Exhibit 2-13 Minimum Radii for Design Superelevation Rates, Design Speeds, and emax = 6% (Non-NHS) ..... 85 Exhibit 2-13a Minimum Radii for Design Superelevation Rates, Design Speeds, and emax = 6% (NHS) ............. 86 Exhibit 2-14 Minimum Radii for Design Superelevation Rates, Design Speeds, and emax = 8% (Non-NHS) ..... 87 Exhibit 2-14a Minimum Radii for Design Superelevation Rates, Design Speeds, and emax = 8% (NHS) ............. 88 Exhibit 2-15 Nonstandard Feature Justification Form ......................................................................................... 91 Exhibit 2-15a Nonstandard Feature Justification Form for Pedestrian Facilities .................................................. 92 Exhibit 2-16 Design Criteria Table ...................................................................................................................... 94

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2.1 INTRODUCTION

NYSDOT has established the following eleven (11) design elements as critical criteria for the design of highways and bridges based on the controlling criteria established by FHWA:

Design Speed Lane Width Shoulder Width Horizontal Curve Radius Superelevation Stopping Sight Distance (Horizontal and

Vertical)

Maximum Grade Cross Slope Vertical Clearance Design Loading Structural Capacity Americans with Disabilities (ADA)

Compliance

Design criteria are influenced by:

The highway functional classification Traffic volumes (from all surface, highway and transit modes) Operating speed Terrain (level, rolling, mountainous) Development density and land use Project type (e.g., new construction, reconstruction, 3R, 2R - simple 3R projects)

Design criteria are presented to provide guidance to individuals preparing the plans, profiles and cross sections. The design criteria for the project alternatives are normally determined during the project scoping stage. In making these determinations, the scoping participants should be aware that the criteria are generally the least acceptable values and, if routinely used, may not result in the optimum design from a safety, operational, or cost-effectiveness perspective. Design criteria values should be established taking into consideration the Department's Context Sensitive Design philosophy that strives for outcomes that meet transportation service and safety needs, as well as environmental, scenic, aesthetic, cultural, natural resource, and community needs. AASHTO's A Guide for Achieving Flexibility in Highway Design, 2004, contains guidance on selecting proposed values that take into account the context of the project.

It is the Department's policy to at least meet the design criteria values for the individual project under consideration. However, the selected values used for a project should be influenced by the design criteria and numerous other factors, including:

? Crash history ? Crash potential ? Future plans for the corridor ? Social, economic and environmental impacts ? Purpose and need for the project (e.g., traffic calming, capacity improvement) ? Context of the highway ? Construction cost ? Stakeholder and public involvement (including the road users and communities that the

highway serves)

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In situations where values do not meet the design criteria values for certain design elements, a formal justification must be prepared in accordance with Department policy for use of the nonstandard feature, as specified in Section 2.8 of this chapter. The use of design exceptions to achieve an optimum design is discussed in AASHTO's A Guide for Achieving Flexibility in Highway Design, 2004.

There are other design elements with established values that must be considered in addition to the critical design elements when scoping and designing a project. These elements can affect some of the critical design elements and have a considerable impact on the cost, scope, and quality of a project. Examples include design storm, length of speed change (acceleration and deceleration) lanes, design vehicle, clear zone, median width, control of access, and level of service. Since these other elements are not listed as critical design elements, they are not addressed in this chapter but are discussed in others (e.g., Chapter 5 Basic Design, Chapter 18 Pedestrian Facility Design, and Chapter 17 Bicycle Facility Design).

The inclusion of specified design criteria in this chapter does not preclude the use of engineering judgment to consider alternative engineering values and does not necessarily mean that existing roadways, which were designed and constructed using different criteria, are either substandard or unsafe. Many existing facilities are adequate to safely and efficiently accommodate current traffic demands and need not be reconstructed solely to meet current design criteria

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2.2 PROJECT TYPES

In order to provide consistent methods for developing projects and reporting program data, projects are categorized into types which are determined by their predominant purpose. When the project consists of two or more different kinds of work, judgment must be used to identify the predominant reason for the project in order to select the appropriate type.

When projects have more than a single type of work, it may not be appropriate to use a single set of design criteria. There may be several sets of design criteria that apply to different portions of the project or to different alternatives. Separate criteria are to be provided for adjoining highways when they are being reconstructed to tie into the new mainline.

2.2.1 Pavement Preventive and Corrective Maintenance

Preventive maintenance is defined as those planned activities undertaken in advance of a critical need or of accumulated deterioration so as to avoid such occurrence and reduce or arrest the rate of future deterioration. Corrective maintenance is defined as those activities to correct existing deficiencies. Both of these activities may correct minor defects as a secondary benefit.

These work types include element specific work such as resurfacing a highway's pavement and shoulders (e.g., 1R/2R resurfacing). Work generally also includes measures to address identified superelevation, pavement marking, signing, delineation, crack and joint sealing, drainage improvements and necessary safety improvements on approximately the same alignment. Refer to Highway Design Manual Chapter 7 for further guidance on 1R and 2R projects.

2.2.2 3R - Resurfacing, Restoration and Rehabilitation

This type of project includes work to preserve and extend the service life of an existing highway, including any safety improvements justified by existing or potential accident problems. Low cost operational improvements are also encouraged. Work is generally limited to pavement rehabilitation along existing alignment, and can include correction of minor subgrade problems, widening of less than a lane width, minor adjustment of vertical and/or horizontal alignment, provision of turning lanes at intersections, arterial driveway consolidation, lengthening acceleration/deceleration lanes and construction of bus turnouts, and pedestrian and bicycle accommodations. These projects may also utilize Intelligent Transportation System (ITS) measures, such as signal retiming and detection, ramp metering, overhead sign structures, and incident detection and management. Work may also include drainage improvement, slope work, and/or replacement of signs and signals, guide rails and other roadside appurtenances. Refer to Highway Design Manual Chapter 7 for further guidance on 3R projects.

2.2.3 Reconstruction and New Construction

This type of project includes work to replace an existing highway, including rebuilding to include geometric improvement, or construction on new alignment. Projects generally involve extensive rebuilding of subgrade, drainage systems, and utility work. These projects may also utilize ITS measures. These projects provide a full depth replacement of hot mix asphalt or Portland

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cement concrete. Highway reconstruction and new construction projects may also include bridge work, including bridge rehabilitation and bridge replacement. Refer to this chapter and Highway Design Manual Chapter 5 for further guidance on reconstruction and new construction projects.

2.2.4 Minor Intersection Reconstruction

This type of project typically provides operational improvements, including geometric changes such as new or lengthened turn lanes, restriping, improved radii, and minor channelization. Other examples of improvements include installation of traffic control devices and signs, installation of sidewalks, curbs and bus turnouts, incidental improvements such as lighting and drainage improvements, and pedestrian and bicycle accommodations. Minor intersection projects do not involve edge to edge full-depth pavement reconstruction. Refer to Highway Design Manual Chapter 5 and Highway Design Manual Chapter 7 for further guidance on minor intersection reconstruction projects.

2.2.5 Major Intersection Reconstruction

This type of project typically includes operational changes, major capacity enhancements, and relocation/realignment work and usually involves full-depth pavement reconstruction. Major intersection reconstruction also includes new or revised access points for freeway interchanges, as defined in Project Development Manual Appendix 8. Major intersection reconstruction may include but is not limited to, major at-grade signalized intersections, single and multi-lane roundabouts, diverging diamond interchanges and restricted crossing U-Turn intersections. These projects may also utilize ITS measures. Refer to this chapter and Highway Design Manual Chapter 5 for further guidance on major intersection reconstruction projects.

2.2.6 Bridge Projects

Bridge projects are projects where the primary objective is to construct a new bridge or to replace, rehabilitate, or repair the deck of an existing bridge. Bridge projects would also include projects where an existing bridge is to be removed. Some incidental highway work may be included on the approaches to the bridges, as a necessary transition between the bridge and the unaffected existing highway. Bridge project types are further broken down as shown below. For additional information, refer to the NYSDOT Bridge Manual.

2.2.6.1 Element Specific Cyclical Bridge Work Element Specific Cyclical Bridge Work is planned activity done in advance of a critical need or accumulated deterioration so as to reduce or arrest the current or future rate of deterioration.

2.2.6.2 Element Specific Bridge Work

Element Specific Bridge Work includes work outside the scope of that in Section 2.2.6.1 and may include such actions as deck repair, bearing replacement, bridge railing upgrades and bridge curb or sidewalk replacement.

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