Highway Engineering

Forecasting Future Traffic Flows 33

Example 2.5 Contd

Solution

Substitute costs and travel times into the above utility equations as follows:

UC =2.4 -0.2 (4) -0.03 (20) = 1.00

UB =0.0 -0.2 (0.5) -0.03 (40) = -1.30

ULR=0.4 -0.2 (0.8) -0.03 (25) = -0.51

e1.0 =2.7183

e-1.3 =0.2725

e-0.51=0.6005

Thus, 3785 commuters will travel to work by car, 380 by bus and 835 by light
rail.

P

P

P

CAR

BUS

RAIL

=++()= ()

=++()= ()

=++()= ()

2 7183 2 7183 0 2725 0 6005 0 757 75 7

0 2725 2 7183 0 2725 0 6005 0 076 7 6

0 6005 2 7183 0 2725 0 6005 0 167 16 7

. ... ..%

. ... ..%

. ... ..%

Example 2.6 – Effect of introducing bus lane on modal split figures
Taking a suburban route with the same peak hour travel conditions for car
and bus as described in Example 2.5, the local transport authority constructs
a bus lane in order to alter the modal split in favour of bus usage. When in
operation, the bus lane will reduce the bus journey time to 20 minutes and
will increase the car travel time to 30 minutes. The cost of travel on both
modes remains unaltered.
Calculate the modal distributions for the 1000 work commuters using
the route both before and after the construction of the proposed new bus
facility.

Solution

The baseline utilities for the two modes are as in Example 2.5:

UC=1.00

UB=-1.30

The modal distributions are thus:

Contd