The design element with the greatest effect on the scale of the roadway is its width, or cross section. The cross section can include a clear zone, shoulder, parking lanes, travel lanes, and/or median. The wider the overall roadway, the larger its scale; however, there are some design techniques that can help to reduce the perceived width and, thus, the perceived scale of the roadway.
Limiting the width of pavement or breaking up the pavement is one option. In some instances, four-lane roadways may look less imposing by designing a grass or planted median in the center. Grass shoulders, such as those often used in many parts of the southeastern United States, limit the perceived width of the roadway and still provide a breakdown area for motorists. These types of shoulders may be appropriate, depending on the context of the area; volume, type, and speed of traffic; and the needs of pedestrians and bicyclists. Green space between sidewalks or non-motorized vehicle paths and the travel lanes also helps to break up the perceived width of the pavement.
Elements (or a lack of elements) along the roadside also contribute to the perceived width of the road and can even affect the speed at which motorists travel. With all else being equal, the wider the perceived road, the faster motorists will travel. Along with horizontal and vertical alinement, cross-section elements, and other elements, such as vegetation along the roadway, buildings close to the road, on-street parking, and even noise walls, may contribute to reducing the perceived width and speed of the road. Considering these elements is important in designing a facility that is compatible with its surroundings.
Source: Flexibility in Highway Design pp. 17-19
Published: 1997
