06/13/2002
Turnpikes Past and Present
The construction and maintenance of a superhighway involves inputs from many fields - politics, science, technology and engineering, mapmaking, landscaping, to name just a few. The politics of planning the route of a proposed highway can be the subject of bitter controversy, especially when the route traverses heavily populated areas such as our part of New Jersey. With the planned route set, the engineers must consider the terrain and how it affects the sharpness of curves, steepness of hills, etc. as well as the right-of-way, which includes the land surrounding the actual road surface, the shoulders and drainage ditches etc. Landscaping considerations include possible plantings to control erosion around the roadbed, as well as to minimize the monotony for the driver. The latter can be important factor in today''s sleep- derived society.
After clearing the right-of-way, the engineers must determine whether the existing soil is suitable as the "subgrade" or whether additional earth of another kind must be hauled in to make a suitable substrate on which to build the roadway. After compacting the subgrade a "base course" of some 6 to 8 inches or so is laid down. The "surface" is then laid down in a thickness that depends on the kind of traffic expected. A superhighway needs a hard surface, the "pavement". The two most popular pavements are concrete and my favorite, macadam. We owe the latter to a Scotsman named John Loudon McAdam, who was Britain''s master roadbuilder back in the early 1800s.
McAdam appears to have been the first to appreciate that dry soil could support heavy traffic, with pavement serving the functions of providing smoothness and keeping the soil dry. His macadam was composed of packed thin layers of crushed rock. Today''s macadam consists of the crushed rock with added asphalt, tar or other materials to fill in the spaces in order to provide watertight seal and also to bind the particles of rock together. McAdam would no doubt be amazed to see the types of vehicles that now travel over his surfaces.
Highway materials and designs are still subjects for researchers hoping to improve the durability of our highways, which now have to contend with multi-unit trucks and those horrid SUVs (author''s personal and oft-stated evaluation). The Federal Highway Administration''s Turner-Fairbank Highway Research Center is one institution that carries on research in this area.
All this rumination on superhighways was brought about by my experience last week driving on what was this nation''s first superhighway of any substantial length, the Pennsylvania Turnpike. Our trip to western Pennsylvania, to attend our beloved Annie''s funeral services, involved driving from Carlisle to Donegal on the Turnpike in a driving rainstorm in my little 1997 Volkswagen Jetta. On a sunny day this drive can be enjoyable, with scenery similar to what you might see in Ireland. On a rainy day, however, the drive can be hellish. For those who haven''t experienced this section of the Turnpike in inclement weather, a little history might give you a better appreciation for one safety feature built into many of our modern superhighways. That feature is the wide median separating opposing lanes of traffic.
To bolster my own knowledge of Turnpike lore, I consulted my trusty 1962 world Book Encyclopedia, as well as a Web site pumpwarehouse.com. I was surprised to find that the first turnpike, a road for which a toll is charged, dates back some 4,000 years. Historical records show tolls being collected for a Persian military road between Babylon and Syria in those early days. In our own hemisphere, the World Book credits the Inca with building an astonishing 10,000 miles of roads connecting their cities. Coincidentally, I have just finished reading an article titled "Empires Across the Andes" by Virginia Morell in the June 2002 issue of National Geographic. This article deals in part with the Wari, a much earlier, longer lasting kingdom in Peru, as being the true road builders. The article cites the Wari "extensive system of highways that is now often erroneously attributed to the Inca." Update your World Book.
The first section of the Pennsylvania Turnpike was opened in western Pennsylvania in 1940. I was 12 years old and living in Mechanicsburg, which is 10 miles from Carlisle. It wasn''t too long before the turnpike had reached Carlisle and I remember the excitement when the Carlisle to Pittsburgh link opened for business. People in our area would take their autos out for a spin on the Pike as their Sunday recreation. There were even some reports of picnicking on the median! The stretch of turnpike from Carlisle to the first tunnel was/is virtually curve-free and straight, an incentive for the heavy of foot to give it a bit more gas.
Unfortunately, in those days, neither the automotive technology nor the human psyche was prepared properly for this newfangled "superhighway". Motorists were burning out their engines on this straight stretch at unheard of speeds of 60-70 mph or more. Such high-speed travel for a prolonged period of time was new to virtually everyone. I recall hearing and reading of accidents caused by drivers essentially being hypnotized when following a car on the Pike. The problem was that they would follow that car even when it pulled off the road, say for a flat tire. The result in a number of cases was a fatal crash, with the following car plowing into the stopped vehicle ahead.
In those days, one of the unusual features of the Turnpike was that, with its many tunnels and thoughtful engineering, the road had no grades that required shifting gears. Automatic transmissions were virtually unknown. Another novel feature was the rest stop, with its Howard Johnson restaurant and Esso gas station, located at convenient intervals only a stone''s throw off the road. On those Sunday outings, you could opt for a bowl of bean soup for a dime (vegetable soup was 15 cents) or, for only a dollar, have your Sunday dinner of fried chicken with soup, 3 hot veggies, salad, bread and butter, drinks and dessert included. During the World War II years, gasoline was rationed and using part of that ration for a Sunday dinner on the Turnpike made it a truly special occasion.
Remember those picnics on the median? Actually, a major design flaw lay in the fact that those medians on that first superhighway were, and even today, are not all that common . Over much, perhaps most, of the western section of the Turnpike, only the common, relatively low concrete divider separates the opposing lanes of traffic. Because of this situation, my wife and I could well have become fatalities on our way to Annie''s funeral. When in a heavy rain, I tend to worry about hydroplaning, which occurs when the car loses traction and essentially skates out of control on a film of water. (Indeed, there was a serious hydroplaning accident that we learned had happened that very day on another nearby highway.) Being cautious, I slowed to about 55-60 mph. Truckers don''t slow down one bit and they pass, throwing back a spray of water that makes it hard to see - annoying but manageable.
However, at one point a truck coming the other way hit a deep puddle and threw up a wall, not a spray, of water in front of it. This mass of water leapt the divider and hit my windshield, not only scaring the hell out me but also blinding me for at least a second or maybe even two. This was in an area where there was no shoulder and a divider on my right as well. I calculate that we traveled between 100-200 feet totally blind before the windshield cleared! Thankfully, we made it safely to our destination. Most of today''s superhighways employ generously sized medians to separate opposing lanes wherever possible so drivers don''t have to contend with such hazards.
Fortunately, the fire alarm that went off at our hotel as we were set to go to the funeral was a false alarm. However, the flat tire that we had as we pulled out of the hotel parking lot was real! Thankfully, our Lamb guy, Harry Trumbore, had driven his car and was behind us. We made it to the funeral and, on a bright sunny day, said our final farewells to Annie.
If you find this second column in a row rather light on science and technology, I hope you understand that it has been difficult to come up with a topic in view of the past week''s events. Next week, I''ll try to compensate by attempting to get at least a crude understanding of the recent theory that our universe started when two membranes banged together. Don''t expect too much!
Allen F. Bortrum
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