Highway Cross-Slope, Lane, Shoulder and Drainage Design in Alberta

The cross-section of a highway determines how it drains, how safely drivers can recover from errors and how well it carries traffic over its life. This course covers minimum cross-slope requirements for common surface types, crown placement on two-, four- and six-lane highways, and how the design width and painted width of through lanes differ on rural undivided highways that are built wider to accept two future asphalt concrete pavement (ACP) overlays. It explains auxiliary and ramp lane widths, parking lane widths on urban roadways, the many functions of shoulders and the design shoulder width for each design designation.

The course then turns to drainage. For rural highways it covers culvert minimum sizes, design return periods, ditch grades and the safety case for the wide trapezoidal ditch, drainage channel types, culvert materials and strength requirements, installation, rehabilitation and replacement methods, culvert slope and invert elevation, riprap and fish passage requirements. For urban roadways it covers the major-minor drainage system approach, allowable ponding and flow depths by posted speed, design storm parameters, stormwater best management practices (BMPs) such as dry ponds, wet ponds, constructed wetlands, vegetated ditches and oil-grit separators, and cost-sharing arrangements with municipalities and developers. It suits highway designers, drainage engineers and reviewers working on provincial highway projects.

What Will Be Covered:

• Minimum cross-slope by surface type and normal crown location for two-, four- and six-lane highways

• Design width versus painted width of through lanes and allowance for two future overlays

• Auxiliary lane, ramp and parking lane widths, including winter snow considerations

• Functions of shoulders and design shoulder widths by design designation

• Rural drainage objectives, minimum culvert sizes and design return periods by road class

• Drainage channel types, ditch grades, trapezoidal ditch configuration and standard height of fill

• Culvert types, metal thickness and concrete pipe class by height of cover, and installation, lining and replacement methods

• Culvert slope, invert elevation, drop inlets, riprap and fish passage requirements

• Urban major-minor drainage systems, ponding and flow depth limits and design storm parameters

• Stormwater best management practices (BMPs) and drainage policy for shared and developer-proposed facilities