Bump-outs (also known as “curb extensions“) have become commonplace in many subdivisions across the country. They are also common in the existing neighborhoods as a means of traffic-calming. The purpose is to provide an additional element in protecting the vehicles parked on the street and enabling shorter, safer crossing for the pedestrian at the intersection. The bump-out can be a costly add-on for a neighborhood considering the additional curb that is involved and additional measures that need to be taken to handle stormwater. Careful consideration should be given whether a bump-out is most appropriate per the situation. In the instances where bump-outs are desired, I have developed a few variations of the bump-out that can effectively manage stormwater with infiltration, calm traffic and ease the costs of additional curbing.
The bump-out image to the right is an alternative to the conventional bump-out where the planting level is reccessed to gather stormwater. The details of this go much further than the illustration shows including the ground plane materials, transition in height from curb to plantings, grading and hydrological features. This bump-out is appropriate and most effective in T-4 (General Urban Zone) along the urban-to-rural transect, however modifications of it may also be effective in some instances of T-5 (Urban Center Zone).