Highway Design Manual

Many hours have and are being spent rewriting this manual with the goal of creating a user-friendly, accurate document. As chapters are finalized, they will be posted to this page. If you are in possession of a hard copy of the 1999 manual, the Department asks that you exchange the existing chapter with the rewrite. As you use the chapter rewrites, please note and submit any changes or corrections to the e-mail address listed below.

Purpose: The primary functions of the New Hampshire Department of Transportation (NHDOT) Highway Design Manual (HDM) are to provide requirements and guidance on current highway design methods and policies, and to assure uniformity of design practice throughout the NHDOT in conjunction with the American Association of State Highway and Transportation Officials (AASHTO) and the Federal Highway Administration (FHWA). Our mission is to plan, construct, and maintain the best possible transportation system and State facilities in the most efficient and economical manner utilizing quality management techniques consistent with available resources and mandated controls. This manual should not supersede the application of sound engineering principles by experienced design professionals.

This manual does not eliminate the need for other references. Directives from the NHDOT office and FHWA, books, publications, and other related material may need to be referred to for further details, clarification, or interpretations. Subsequent Official Issuances by the NHDOT may supersede portions of the material in this manual. Known holders of the bound 1999 Version of the Highway Design Manual will be notified, as changes are made available.

Variations from this manual will be necessary for special or unusual conditions, or between the issuances of new or revised source documents and any corresponding updates of the HDM. Consequently, instructions in this document are not intended to preclude the exercise of individual initiative and engineering judgment in reaction to site-specific conditions. It is important that there be consistency statewide in the application of this manual. The objective is uniformity of design for the same or similar conditions. Justifications for variations from this manual are to be appropriately documented.

WARNING: Website information is subject to periodic change and/or updating without notice. Anyone relying on such information must bear the risk that the information downloaded previously may not be the most current version available. It is the user's responsibility to check often for updates.

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1999 Highway Design Manual Vol. 1

Contents

• Chapter 2 - Project Development
• Chapter 4 - Alignment and Typical Section
• Chapter 5 - Geometrics
• Reference

1999 Highway Design Manual Vol. 2

• Chapter 4 - Wetland Plans
• Chapter 5 - Construction Plans (37 sheets)

Current Highway Design Manual Vol. 1

Contents

• Chapter 1 - Organization
• Chapter 2 - Project Development
• Chapter 3 - Design Consideration and Criteria
  • Release Memo
  • Chapter 3: Text
  • Appendix 3-1: Design Exception
  • Appendix 3-2: Vertical Clearance
  • Appendix 3-3: FHWA Process for Crashworthiness
• Chapter 4 - Alignment and Typical Section
• Chapter 5 - Geometrics
• Chapter 6 - Drainage
  • Chapter 6: Text
  • List of Major Revisions
  • Appendix 6-1: Erosion & Sedimentation Control and Stormwater Management Policy
• Chapter 7 - Highway Structures
  • Release Memo
  • Chapter 7: Text
  • List of Major Revisions
  • Appendix 7-1: Flexible Pavement Analysis
• Chapter 8 - Quantity Computation
  • Release Memo
  • Chapter 8: Text
  • List of Major Revisions
  • Appendix 8-1
  • Appendix 8-2
  • Appendix 8-3
  • Appendix 8-4
  • Appendix 8-5
  • Appendix 8-6
  • Item 618 Calculation Sheet
• Chapter 9 - Utilities
  • Release Memo
  • Chapter 9: Text
  • List of Major Revisions
  • Appendices
• Chapter 10 - Right-of-Way
  • Release Memo
  • Chapter 10: Text
  • Appendices
• Chapter 11 - Special Plan Elements
  • Release Memo
  • Chapter 11: Text
  • List of Major Revisions
  • Appendix 11-1: Bicycle Railing for Highway Applications Memo
  • Appendix 11-2: Size of Snowmobile Underpass Letter
  • Appendix 11-3: NHDOT Review Procedure for Projects with Guardrail
  • Appendix 11-4: NHDOT Guidance For Guardrail Design Applications
  • Appendix 11-5: Summary Listing of MASH tested Hardware (July 2019)
  • Appendix 11-6: FHWA Implementation Memo for MASH (January 2016) and NHDOT Revised Process for Crashworthiness
  • Appendix 11-7: Non Mash Design Exception
  • Appendix 11-8: NHDOT Memorandum: Recommendations for the Installation of Steel Post Guardrail on New Hampshire Highways
  • Appendix 11-9: FHWA Safety Memorandum, Appendix D FAQs (Cor-Ten) and Forest Service Letter to NHDOT (Cor-Ten)
  • Appendix 11-10: NHDOT Cor-Ten Guidance
  • Appendix 11-11: Long Post Guidance – Washington State Design Manual Section 1610
  • Appendix 11-12: Energy Absorbing Guardrail and Older Legacy Terminals (April 2021)
  • Appendix 11-13: Technical Advisory TA 5040.32
  • Appendix 11-14: Attaching Guardrail to Existing Barrier Memo
  • Appendix 11-15: Rumble Strip Guidelines – May 22, 2019
  • Appendix 11-16: Fire Lane Preemption Systems Memo
  • Appendix 11-17: ITS Mainstreaming Funding Approval Process
  • Appendix 11-18: Memorandum: TCC Project Review Presentation Exemptions and Mandator Reviews (Categorical Exclusions) Memo
  • Appendix 11-19: TCC Memorandum Template
  • Appendix 11-20: TCC Work Zone ITS Implementation Memo
  • Appendix 11-21: TCC Instructions for Level I and Level II TMP Development
  • Appendix 11-22: TCC Level of Significance Template Memo Level II
  • Appendix 11-23: FHWA Memorandum: Federal Participation on Haul Roads and Detours
  • Appendix 11-24: NHDOT Memorandum: Median Crossover Usage
  • Appendix 11-25: Sample Special Provision for the Use of Median Crossovers
  • Appendix 11-26: FHWA SOP for New or Revised Interstate Access Points (March 28, 2011)
  • Appendix 11-27: SOP – Temporary Interstate Access Request
  • Appendix 11-28: Municipal Work Zone Agreement (MWZA) – Sample
  • Appendix 11-29: MWZA Memorandum to the Executive Office – Sample
  • Appendix 11-30: MWZA Letter to Municipality – Sample
  • Appendix 11-31: MWZA Letter back to Municipality – Sample
  • Appendix 11-32: Sidewalk Maintenance MOA – Sample
  • Appendix 11-33: Landscaping Maintenance MOA – Sample
  • Appendix 11-34: Landscaping Design Request – Template
  • Appendix 11-35: Limited Reuse Soils Project Development Policy Directive
• Chapter 12 - Field Work
  • Chapter 12: Text
  • List of Major Revisons
  • Appendices
• Chapter 13 - Plans, Specifications, and Estimate
  • Chapter 13: Text
  • List of Major Revisons
  • Appendices
• Glossary

Current Highway Design Manual Vol. 2

Contents

• Plan Development Checklists
• Chapter 1 - Typical Sections
• Chapter 2 - Sample Layouts
• Chapter 3 - Right-of-Way Plans