Civil Engineering Reference
In-Depth Information
Research has shown that congestion may reduce the number of job destination
opportunities available: it has been reported that some employers, concerned with
work attendance reliability, favor hiring people who live close to the company over
hiring those who may be late in getting to work because of congestion [
2
,
5
].
13.1.2 Congestion Impacts on Business Costs
A survey of business leaders in Portland, Oregon [
6
,
7
] reported the following
congestion impacts on business production costs:
Costs of additional drivers and trucks due to longer travel times;
Costly
'
rescue drivers
'
to avoid missed deliveries due to unexpected delays;
Loss of productivity due to missed deliveries;
Shift changes to allow earlier production cut off;
Increased inventories;
road congestion is perceived as a more serious
problem by managers of trucking companies engaged
in intermodal operations
,
particularly private and for-hire trucking companies serving airports and rail ter-
minals, companies specializing in
refrigerated
transport and private companies
engaged in
Less-Than Truck-Load (LTL)
operations
Golob and Regan [
8
] report that
“
”
.
NCHRP Report 463 [
9
] identi
es three types of business costs impacted by
traf
c congestion:
i. Direct travel costs of all business-related travel, including vehicle operating
expenses and the value of time for drivers (and passengers);
ii. Logistics and scheduling costs, including effects on inventory costs such as
stocking, perishable items, and just-in-time (JIT) processing;
iii. Reduction in market areas for workers, customers and incoming/outgoing.
Just-in-Time (JIT) Inventory Costs
JIT production techniques have led business to demand a faster, more frequent and
more reliable supply of goods to reduce inventory costs. A study reported that
JIT
methods increased deliveries by a factor of two and decreased the size of deliveries
by about half
“
”
[
9
,
10
]. This JIT-induced truck volume demand adds to urban traf
c
congestion (which negatively impacts travel time reliability).
Since travel time reliability is critically important to JIT operations, business will
see inventory costs increase as travel time reliability is reduced with increasing
congestion.
Transit Operating Costs
Congested roadways slow down transit vehicles. This causes longer round trip
cycle times that require more vehicles in service to meet travel demand, additional
operator costs, and higher fuel consumption. These conditions increase the cost of
operation.
