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Subproblem 1b - Page 2 of 5

ID# C301B02

Sub-problem 1b: Determining the Facility Class and Scope of the Analysis

Let's discuss each of these issues and how each affects the operational analysis that we are about to complete.

Why is there a further distinction within facility types? This question must be addressed separately for the arterial and two-lane highway portions. We will begin with the arterial portion. The need for various class types is important, because it represents the driver's ability to travel at a desired speed while considering the various influences on the urban street. In the case of a Class IV facility, one might put less emphasis on arterial throughput and speed as compared to a Class I facility; thus the level of service standards might be different in each of these cases.

The two-lane highway is typically within a much more rural environment; and the distinction separates roadways where drivers expect to travel at high speeds (Class I), as compared to those facilities that might provide more of a recreational function (Class II).

What parameters contribute to the distinction? For urban streets (arterials), the parameters that contribute to the distinctions include the level of roadside development, posted speeds, cross section, pedestrian activity, signal spacing or any other characteristics that would suggest differences in motorist perception of the quality of service. It is these differences that contribute to the slight disparities in running time, which are used to provide an indication of travel speed.


For two-lane highways, it is primarily the length of the trip, or type of trip that offers the distinction between the class type.


Are the segments under consideration homogenous throughout? In our case, the facility is approximately seven miles long with nearly equal signal spacing and no discernible differences in any of the other characteristics that would influence motorist expectations. Therefore no reasons can be offered for creating more than one facility for analysis purposes. So the only question that remains is, what class should be assigned to this facility? We have four classes from which to choose:

  1. Class I: High speed

  2. Class II: Suburban

  3. Class III: Intermediate

  4. Class IV: Urban

Based on what we know of the area, which of these classes can we eliminate from further consideration?

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