Vertical Visual Cues
One of the most important reasons to landscape a roundabout is to provide a visual vertical cue for approaching drivers. Roundabout are often located at awkward intersections with odd angles of approach. They are a new concept for American drivers. Without the warning, someone confused by the traffic flow requirements might drive right through the central island. Lighting is another essential for roundabout as a visual warning at night, especially for high speed approach settings.
The landscape in the picture has been providing decades of delight for locals, directing traffic with soft vegetation, and preventing accidents by providing a block to errand drivers that might over run the traffic separator. It is fairly self-sustaining in design. The low, evergreen hedge of Yaupon Hollies hides a lot of the leaf debris that falls from the small-scale trees, and the leaf litter from the trees mulches inside the ribbon of evergreens to suppress weeds.
The trees in most roundabouts need to be small for a small roundabout island. These trees are dwarf Acoma Crapemyrtles, with multi-stem trunks that generally stay less than four inches in diameter, and might break away if hit by a vehicle. That’s good. You don’t want to place solid structures and fixed objects in the stopping distance path of automobiles that might run off the road.
If local groups want to embellish the design, they can add herbaceous perennials around the outside ring of the low hedge for a very nice, colorful effect. For years when the budget is limited, the outer ring can be left unadorned.
A simple, low-maintenance design that has proven its sustainability over many years is of special value, especially for a public setting. This one works and provides an attractive and important safety prompt for oncoming traffic.