**Sub-problem 1a:
Analysis of the existing TWSC intersection**

Level of service (LOS) for a TWSC intersection is determined by
the control delay and is defined for each movement, but LOS
alone does not tell the whole story! Besides LOS, other performance measures
that should also be considered include the volume/capacity ratios and the
estimated queue length. Let's investigate each of these measures of
effectiveness in greater detail (see
Exhibit 1-9).

First, note that the left turn movements on the major
street (NBLT and SBLT, movements 1 and 4), experience acceptable
delay. The HCM methodology estimates that both movements will experience
level
of service A, with less than 10 seconds of control delay per vehicle. We
can also see that the movements on the minor street
approaches (westbound on Styner and eastbound on Lauder) experience moderate
to high levels of delay. Both left turn movements (movements 7 and
10), for example, operate at level of service E with delays of 36 and 47
seconds, respectively.

The volume/capacity ratio is also important to consider
because it tells us how close we are to capacity for each
movement. Here, the v/c ratio is less than 0.60 for all movements. Thus, there is ample capacity available for the existing conditions.

Queue length is always an important consideration at an
unsignalized intersection, and especially when it is necessary to
determine the adequacy of turning bays or when there is the possibility of a
queue spilling back into the adjacent upstream intersection. In the
case of the Styner-Lauder/U.S. 95 intersection, the
95th-percentile queue length estimates are less than four vehicles, meaning that there is
sufficient space to store vehicles as they are waiting to enter the
intersection. Even so, the queue length requirements for the right turns
from the minor street (movements 9 and 12) are 3 vehicles. This is a length that some drivers might consider to be
excessive (even though it only has a 5 percent probability of occurring), and especially so for drivers in a smaller community like Moscow.