**Sub-problem 1b: Analysis of
the Eastbound Freeway Section**

The result for our
situation is *S* = 54.8 mph. If you take this value and divide it into
the peak 15-minute flow rate, *v*_{p}, then you get the freeway
segment’s peak 15-minute average density (passenger cars per mile per lane),
which is the basis for assessing the LOS (see
Dataset 1):

*
D*
= *v*_{p} / *S* = 1,902 pcphpl / 54.8 mph = 34.7 pcpmpl

Where pcphpl means
passenger cars per hour per lane, mph is miles per hour, and pcpmpl is
passenger cars per mile per lane. The breakpoints in *D* for level of
service are as follows, all in passenger cars per mile per lane: A: 0-11; B:
11-18, C: 18-26, D: 26-35, and E: 35-45. Above 45 is LOS F.

For the circumstances
we’ve examined, where *D* = 34.7, the LOS is a high D, almost E. Since
we picked the 90^{th} percentile value to evaluate, this means that
10% of the time the eastbound LOS in the peak hour is D or worse, and 90% of
the time it is better than that.

Three
other significant conditions have the following levels of service: