Highway Alignment and Sight Distance Design in Alberta

A crest curve that looks fine on the profile can still hide a stalled vehicle from a truck driver at highway speed. Getting alignment right means knowing which eye height, object height and sight distance criterion governs each situation, and where there is room to trade a minimum value for construction savings without compromising safety. This course takes you through the alignment elements used on Alberta highways, from the basic criteria for stopping, passing and decision sight distance to the geometry of curves, grades and auxiliary lanes.

You will work through horizontal alignment controls, including side friction factors, minimum radius, rural and urban superelevation rates, the distribution of superelevation and side friction, superelevation development and spiral curve design. The vertical alignment material covers maximum and minimum gradients, truck performance on grades, drainage-driven minimum grades and K values for crest and sag vertical curves, including sight distance at underpasses. The course closes with the practical design of climbing and passing lanes (warrants, tapers, lengths, spacing and sight distance at lane ends), construction practice at four-lane to two-lane highway transitions, and the alignment, design speed and surfacing of temporary highway detours through work zones. It suits highway designers, transportation engineers and reviewers who prepare or check geometric design work in Alberta.

What Will Be Covered:

• Driver eye height and object height criteria for sight distance

• Stopping, passing, no-passing-zone and decision sight distance

• Horizontal alignment controls, side friction factors and minimum radius

• Rural and urban superelevation rates, distribution of e and f, and superelevation development

• Spiral curve form, properties and design parameters

• Sight distance on horizontal curves and urban fringe transitions

• Maximum and minimum gradients and vehicle operating characteristics on grades

• Crest and sag vertical curves, K values and sight distance at underpasses

• Climbing lane and passing lane warrants, geometry, location and length

• Typical four-lane to two-lane highway transitions and temporary highway detours