Transitions refer to a change in the width or speed of a thoroughfare. In terms of geometric design, transitions refer to the provision of an adequate taper where lanes shift or narrow, shoulders widen, lanes diverge or merge, and where deceleration lanes are provided. Geometric transitions are usually required when there is a change in the thoroughfare type and associated change in width, particularly where functional classification and speed changes, and where a change in the width of roadway, either a narrowing or widening of lanes, or a decrease or increase in number of lanes is introduced.

Last edited by jp.   Page last modified on July 13, 2006