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

You can compute the
LOS by hand, but most software packages won’t let you do a single lane
analysis directly. So you need to do a work-around. To begin, you can assume a volume
of 1,620 passenger cars per hour and a two-lane facility. That yields a LOS
of B and a density of 16.4 pcpmpl. So the truck climbing lane, if it’s used
just by the trucks, operates adequately (see
Dataset 7).

Next we need to check
the remaining two lanes to see how they would operate if no trucks were
present. The cars are 95% of the traffic stream, which means
a volume of 3,080 veh/hour. On two lanes, with 0% trucks, that yields a per
lane flow rate of 1,711 pcphpl, a density of 31.1 pcpmpl, and a LOS
of D. The average passenger car speed is 55 mph (see
Dataset 8).

Now let's consider the results
of this hypothetical scenario. If we assume all three lanes are used by all the traffic, we
get a density of 26.2 pcpmpl. If we separate the trucks into the truck
climbing lane, we get 16.4 pcpmpl for the truck climbing lane and 31.1
pcpmpl for the remaining two auto-only lanes. These results suggest that trying to
enforce exclusive use by trucks of the truck-climbing lane wouldn’t be a
good idea.