There are so many, landing a man on the moon, harnessing atomic energy and many others however I nominate the humble highway or specifically the Interstate system . Now approaching the 50,000 mile mark it is considered the largest public works project in the entire worlds history.
One mark of the overwhelming success of the Eisenhower Interstate System is that the American people take it for granted, as if has always been there, like the Mississippi River or the Rocky Mountains. The Interstates are so much a part of the daily life of Americans that most people do not realize that the system they use to get to work, to school, to the mall, and to their vacation destination could be considered one of the "wonders of the world."
In 2006, the Federal Highway Administration (FHWA), State departments of transportation (DOTs), and transportation partners in the private sector will have the opportunity to remind the American people that the Interstate System is not a natural phenomenon, but rather the result of dedicated men and women working for five decades to enhance the mobility that has always been part of the American dream. Those years of challenge and controversy were also a period of technological evolution, environmental stewardship, and, most of all, commitment to the goal of building the Dwight D. Eisenhower National System of Interstate and Defense Highways.
You can drive I-80 from New York to San Francisco and never have to stop, of course you can drive from practically most urban areas and never have to stop (assuming you don't run into big traffic jam). Another interesting footnote is the Pennsylvania Turnpike is also know as Americas first superhighway. As much as many people grumble about it and issues such as the lanes being right next to each other it's interesting to note that today's standards do not meet those of the turnpike, a road like this will not be built today. Considering the terrain it is one of the flattest and straightest pieces of real estate in the world with banked corners.
The Pennsylvania Turnpike project limits were from Middlesex, located west of Harrisburg, to Irwin, east of Pittsburgh, a distance of 160 miles. For the project to be constructed on schedule in a mere 20 months, 1,100 engineers were employed. Noteworthy was the consistency of the design standards of the turnpike, much different than previous piecemeal attempts to build roads through different areas. Plans called for a 200-foot right-of-way with two 12-foot lanes of travel provided in each direction with medians, berms, long entrance and exit ramps, banked curves, and separated grade crossings.
Revisions made during the course of design included changing from two asphalt and two concrete lanes to all concrete lanes. A four-foot median was replaced with a ten-foot one. Although Vanderbilt's railroad bed was originally planned for a maximum two percent grade, the maximum grade selected for the turnpike was three percent, which an automobile could easily tolerate but was still much less than the nine to twelve percent grades on local highways. At first a tunnel was considered near Everett, but later it was decided to remove 1.1 million cubic yards of rock and earth to create the largest open cut of its time.
A standard sight distance of 600 feet was chosen. Straight-aways were designed for 100 mph and the spiral curves were superelevated to accommodate 70 mph. Easy grades were carved through valleys, ravines, and mountains. Almost 70 percent of the original turnpike was straight, with the longest a 40-mile stretch west of Carlisle relieved by one curve to break the monotony.
Many innovations were introduced during the layout of the highway. When possible, the turnpike route was laid out on southern exposures to let the sun heat the ice and snow on the roads. Toll booths off of the turnpike were located on downhill grades to allow drivers time to react instead of being surprised. In addition to the roadway, there were over 300 bridges and culverts, nine interchanges, ten service plazas, and eleven toll booths to design.
http://www.paturnpike.com/news/americas ... ghway.aspx