Road Tunnel Geometry

The Road Tunnel Geometry online PDH course is a part of the Geotechnical Engineering category of courses. This course provides general geometrical requirements for planning and design of road tunnels.

As defined by the American Association of State Highway and Transportation Officials (AASHTO) Technical Committee for Tunnels (T-20), road tunnels are defined as enclosed roadways with vehicle access that is restricted to portals regardless of type of structure or method of construction. Road tunnels following this definition exclude enclosed roadway created by air rights structures such as highway bridges, railroad bridges or other bridges.

The topics discussed in the course include horizontal and vertical alignments; clearance envelopes; and cross section elements. Geometrical requirements for the tunnel approaches and portals are also presented. It often takes several iterative processes from planning, environmental study, configuration, and preliminary investigation and design to eventually finalize the optimum alignment and cross section layout.

The online PDH course is based on Chapter 2 “Geometrical Configuration” of the US Department of Transportation, Federal Highway Administration publication tilted, “Technical Manual for Design and Construction of Road Tunnels – Civil Elements” (FHWA-NHI-10-034). This course is intended to be used by geotechnical, civil and structural engineers and others interested in learning about tunnel planning, design and construction.

Learning Objectives

At the end of the course, you will be able to:

• Apply governing standards regulating road tunnel geometry
• Explain different tunnel shapes and types
• Discuss tunnel horizontal and vertical alignment
• Specify travel clearances
• Explain tunnel design elements such as typical cross sections, travel lane and shoulder, sidewalk and emergency egress walkway
• Discuss other tunnel design criteria such as drainage, lighting, ventilation and traffic control