Civil Engineering Reference
In-Depth Information
Chapter 10
The Impact of Traffic Congestion
on Mobility
10.1 De
ning Mobility
Mobility is the ability of people and goods to travel easily, safely, quickly and
reliably. Trip mobility varies with the speed of travel, and it may be de
ned as the
number of trips taken and their distance (trip-miles) within the traveler
'
s daily travel
time and cost budgets. Therefore, lower speeds resulting from traf
c congestion
reduce mobility.
This chapter has two basic objectives: (1) to de
ne and quantify traveler
mobility, and (2) to determine how mobility is impacted by traf
c congestion.
10.2 Factors Influencing Mobility
Mobility depends on three key factors: (1) the type of transportation modes available
to the traveler (e.g., walk, bicycle, bus, rail, private vehicle); (2) traveler
'
s require-
ments and needs that in
uence mode selection (e.g., travel time budget, physical
ability in using a given mode, affordability, trips purpose, and the license to drive);
and (3) the operational characteristics of the travel modes (e.g., speed, reliability, cost,
safety, comfort/convenience, and the absence of physical barriers to using the mode).
Figure
10.1
shows how these factors interact in determining a traveler
fl
'
s mobility.
10.2.1 Traveler Requirements/Needs
Traveler requirements/needs include:
Travel Time Budget
: the time one allocates daily to travel. Daily travel time
budgets have remained relatively stable over time and across metropolitan areas
