Transportation Structures:
Route Treatments

The Evolution / Metamorphosis of Trails and Roads


An esoteric, detailed analysis of a mundane, commonplace thing: roads...


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

Original Route Structure:
The Data

This is the original situation (at least after humans lightly altered the landscape): the route is an aboriginal trail running as direct 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 and tight turns are acceptible.


Trail & Terrain Trail

The trail, without terrain and waterways, illutrates its bare-bones shape.


The course of the trail (and it vector(?)) runs southeast-northwest. Since a transportation route is almost always travelled both directions, there is no forward or backward in this analysis (except where necessitated by convention, such as with numbering or lettering):

Route Course Route Headings / Segments

The headings of the trail run from point to point, generally heading southeast-northwest. The headings demarcate segments of the trail (and route): a stretch of the transportation structure between recognizable locations (such as a bend in the route or abrupt change in elevation).


The trail, with terrain and waterways, illustrates its component route types and subtypes:

Route Types Route Elements

The trail, without terrain and waterways, illustrates its component elements.


Modification:
Bypass

With transformation from a trail into a road, the trail is modified to accomodate wheeled vehicles. The sway is a target for elimination: it avoids wet terrain that can now be drained and/or a diked roadway built across with the increasing construction ability and skill; and in the automotive age, the curve become increasingly dangerous to increasingly faster auto traffic.


The curve is bypassed.

One option is to leave the sway intact but as a less-used stretch of road. The sway has become a

Demoted road segment
.


Another option is to to leave the sway mostly intact as a dead-ended stretch of road. This is usually done to allow access to property on the old stretch of road, without the trouble of traffic leaving or re-entering the road at two places. The segment usually become the lowest-level road classification or a private lane. The sway has become a

[Dead-Ended] road segment
.


A third option is to simply abandon the sway, if no access to property is needed. The old stretch of road is either left to degrade and erode, or the pavement is removed and sometimes any grading is undone. The sway has become a

Abandoned road segment
.


Modification:
Converted

With transformation from a trail into a road, the trail is modified to accomodate wheeled vehicles. The sway is a target for elimination: in the automotive age, the curve become increasingly dangerous to increasingly faster auto traffic. If the wet terrain can not be drained and/or a diked roadway built across by choice or practicality, the route can be adjusted without altering it beyond recognition.~


Instead of bypassing the curve, one option is to lessen the curve. The more offensive end (or ends) are adjusted to be more gradual. The sway has been converted into a

[Smoothed] road segment
.

This is usually done for only an auto highway.


As original routes are incorporated into the settlement landscape, sometimes the land division sysytem is so overpowering that most roads are adjusted to coincide with the system if the terrain allows. The is most apparent in the Section-Line Road System, which is a reactangular grid applied arbitrarily over the terrain. With that influence, the sway has been adjusted into a series of straight tangent, and has been converted into a

Rectangularized road segment
.


With adjustment into a series of straight tangents, and conversion into a rectangularized road segment, the formerly naturalistic, responsive, smooth route has become a mechanized object. With the addition of other roads controlled or influenced by the Section-Line mentality, the original route may be hard to distinguish. By its conversion and its new context, it has been

Obscured
.


Images greated in Freehand for Macintosh, which aided greatly by providing 'handles' to aid in creating curves vs. bends.]



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v1.2 - 7/5/04, 10/25/02, 7/5/02
© Intrepid Historical Services - Kevin B. Coleman
Chillicothe, Ohio, USA