A stone bridge another of the unique overpasses on the Merritt Parkway.
An excellent example of a holistic design approach is the Merritt Parkway in Connecticut. Designed and built in the 1930's, its overall design philosophy was to build a graceful highway set in a natural environment. This was achieved by using long, gradual vertical curves, rounding out rockcuts to produce a natural appearance, and most important, integrating the traveled way into the terrain through choice of alinement and a carefully planned landscape. The result was a highway that not only met traffic demand, but was also a scenic escape for inhabitants of the urbanized areas it served.
Traveling along the 61km (38mile) route today, it's easy to see how all the elements of the roadway fit together to achieve this parkway concept. The setting, with its vegetation, appears natural. The pavement width is minimal; opposing traffic is separated by a grass median and most shoulders are covered with grass. Despite the population growth that has developed around the parkway, and in many cases directly up to the parkway, the density of trees and the carefully planned topography hide this development from view. One of the most striking features of the parkway is its bridges. There are 72 in all (35 of which carry intersecting crossroads over the parkway), and each is designed differently. Even the materials used vary considerably, from stone to concrete to steel, yet they all work together, because they are all designed within the same scale. They are all approximately the same length and height, which gives the appearance that they all belong together, despite the fact that some are arch construction and some post and beam.
For existing roads, where improvements may only involve a small section of the road, there may not be the need to develop an entirely new concept for the roadway. In fact, it would probably be inappropriate to do so, because the result would be that one small section of the roadway looked much different than the rest. It is important in these cases to be consistent with the existing design of the overall route, using the information gathered to assess the character of the area and to design with sensitivity to that character.
An exception might be when the environment of the road changes along a short section. For instance, a rural collector may change characteristics as it enters a town and becomes an urban street for a few blocks, then changes back to a rural collector. Designers working on the urban section of the street do not have to be consistent with the look of the road outside the urban environment, because its character is so different. Both the urban and rural sections should, however, maintain the same general scale in terms of roadway width.
