Sub-problem 2b: Analysis of the Center Section of Krome Avenue (Class II Two-lane Highway)

Step 2. Results

It was determined in Problem 1 of this case study that the center section of highway has some the characteristics of a Class I and Class II facility and should ideally be investigated using both classes. It must be noted, however, that HCM Exhibit 12-15 provides service volume estimates only for Class I facilities, so the option of a Class II facility cannot be determined using HCM Chapter 12.

This sub-problem will be carried out in the same manner as sub-problem 2a, using the service volumes for LOS A-E given in HCM Exhibit 12-15 as a function of the free-flow speed (45-65 mph) and the type of terrain (level, rolling, or mountainous). The terrain is very flat as is typical for all coastal Florida highways. The free flow speed for this section has been determined from field observations as 50 mph, which is 5 mph lower that the value used in sub-problem 2a. The design hour volume has been determined from field observations as 1,190 vph, which is 90 vph higher than the sub-problem 2a volume. The combination of a lower free-flow speed (which produces lower service volume thresholds) and higher traffic volumes suggests that the performance of this section will not be as good as the north section discussed in sub-problem 2a. The question at this point is whether or not the difference will be great enough to cross the LOS D threshold.

The following table shows the results of this analysis. The LOS thresholds are taken from the portion of the table that applies to level terrain with a free-flow speed of 50 mph. Note that the absence of a threshold entry for LOS A and B indicates that it is not possible to attain either LOS A or B with a free flow speed of 50 mph.

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