"Many roads currently exist that were not built to today's standards. These roads may be located in restricted right-of-way corridors that have scenic or historic resources adjacent to the roadway. It is necessary to try to avoid impacting these resources when considering highway improvements."

Restricted Right-of-Way

Many roads currently exist that were not built to today's standards. These roads may be located in restricted right-of-way corridors that have scenic or historic resources adjacent to the roadway. It is necessary to try to avoid impacting these resources when considering highway improvements.

Solution

One option, as has been discussed previously, is to reconsider the functional classification and design speed of a particular section of highway, because these decisions go a long way toward defining the basic design parameters that can be used in connection with an improvement of the facility. Lowering the design speed or changing the functional classification results in a lowering of the minimum width dimensions for the cross-sectional elements.

Another option is to maintain the road as is or as a 3R project. Design criteria established by States are generally lower for 3R projects than for reconstruction projects. A third option is to seek design exceptions. Whichever alternative is chosen, the designer should try to maintain consistency in the roadway cross section. If only a small stretch of highway is located within restricted right-of-way, it would be unsafe to narrow that stretch while maintaining a much higher roadway width before and after it.

A successful resolution of the design of a highway cross section was found during the planning and design for the State Route 9A project along the Hudson River in Manhattan. The existing at-grade "interim" facility had two 3.6-m (12ft) lanes in each direction, separated by a 4.6-m (15-ft) flush median with a Jersey barrier.

The preferred alternative, which is now under construction, replaces a rather unattractive urban street, with a six- to eight-lane divided urban boulevard that has a landscaped median. The new design incorporates extensive landscaping and separate bikeways and pedestrian walkways. The width of the travel lanes was reduced from 3.6 m (12 ft) on the existing surface street to 3.4 meters (11 ft) on the new urban boulevard. This cross section accommodates traffic demands and dramatically enhances the physical environment of the project area. More information about this project is in the case study section of this Guide.