Civil Engineering Reference
In-Depth Information
Fig. 7.2 Freeway lane imbalance
Fig. 7.3 Route convergence
and lane imbalance along
sections of the Gowanus
Expressway, Brooklyn, NY
Geometric Constraints: Sharp curves, steep vertical grades, and narrow lanes
cause vehicles to slow down (Fig.
7.5
). For example, large trucks going on a
steep upgrade can create long queues of vehicles in back of the truck.
Short Auxiliary Lanes: Auxiliary lanes on approaches to signalized intersec-
tions (Fig.
7.6
) are sometimes too short to prevent queued up traf
c waiting to
turn left or right from blocking the through movement, causing large losses in
throughput capacity of the intersection.
Inadequate Access Control: Too many curb cuts and driveways create con
fl
icts
between through traf
c and vehicles entering/exiting from parking lots/garages
or driveways (Fig.
7.7
).
