Transportation Structures:
Route Treatments:
Vertical Profile

The Evolution / Metamorphosis of Trails and Roads



By necessity, this discusion deals only with land-based transportation structures: trails, roads, and canals.

The Terrain

This is the example terrain: a gradual slope, with several benches.

All the following hytpothetical transportation treatments have the same goal: to reach the same destintion. This means that they all have the same course, though they use different headings and routes to get there.



The Trail

This is the original transportation situation (at least after humans lightly altered the landscape): An aboriginal trail running as directly as possible between destinations, staying as level as possible though using the terrain to its optimum. Since all trafic is on foot, short steep grades are acceptible.



The Road

As Euro-American settlers increase their use of the trail it becomes a road. More extreme bends and slopes in the trail that kept it closer to the course are reduced or eliminated, sometimes necessitating a less-direct series of courses.



The Turnpike

The road is further modified by "Turnpiking" or "Piking" it. The new turnpike road is more tangential than the road: instead of smooth curves, the turnpike road is typically a series of straight tangents on the same general course. These tangents indicate less concern about the terrain, and force the road into more extreme grades.



The Canal

The canal is much different from the trails and roads: it is an artificial waterway. Since water needs either a level basin or sloping course, the canal combines both, and adds water stairsteps (locks) to accomodate any slope more than slight.

The Canal Levels are actually not perfectly level; they have a minimal slope to keep the water flowing so that the locks are kept filled at the lower end of each level. (This is an example of the surveying skill present in the early nineteenth century, and even back to the late seventeenth - a skill little known or appreciated by modern people.



The Highway

The turnpike road is further modified. High-speed automobiles require gentler curves and can tolerate longer, uninterrupted, but gentler slopes, slopes too long that would wear out a beast of burden (q.v. Eric Sloane). A highway is created.

Complex engineering is required to calculate proper curves and elevation, especially to conform to transportation safety regulations. With the availability of heavy earth-moving machinery, the only limit to reshaping of the terrain is cost.



Altogether, Now

A comparison of all five transportation tranfoms illustrates the different needs, techniques, and results of different transporation methods used to reach the same destintion.

[mention Freehand, and handles' aid in creating curves vs. bends?]


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