Civil Engineering Reference
In-Depth Information
Fig. 5.8 Percent growth
in peak period vehicle trips
for non-work purposes,
1990
−
2001.
Source
Reference [
9
], Exhibit 1,
August, 2007
women, while a larger portion of the people shopping (including getting a meal) are
men. Nearly 80 % of travelers who drop off a passenger during the AM peak live in
households with young children. Retired people are more likely to shop or go to the
doctor.
Non-work travel has increased substantially during the workday peak periods.
From 1990 to 2001, the percent growth in peak period vehicle trips for non-work
travel increased by 100 % in the AM peak and 35 % in the PM peak (Fig.
5.8
)[
10
].
Non-work trips are increasing both in the number of workers making such trips
and in the number of stops per worker [
11
]. Since 1994, 25 % more commuters stop
for incidental trips during their commute to or from work, and stopping while
commuting to or from work is especially prevalent among workers with the longest
commutes [
7
]. This type of trip chaining is increasing.
Peak period congestion, therefore, is not solely caused by commuter travel but it
is also caused by the increasing concentration of non-work trips into the traditional
commuter peak period.
5.4.3 Peak Spreading
The growth in non-work travel during the peak period is a major reason why
congested conditions extend into the shoulders of the peak hours.
Table
5.6
[
12
] shows how the shares of total trips entering the Manhattan CBD
in the morning peak hour and peak period, have declined over the last half century
(1960
2009), as travelers shifted their trips outside the peak periods. Over time, the
-
typical
“
rush hour
”
has gradually been transformed into the
“
rush hours
”
as trav-
elers leave earlier or later to avoid the worst congestion period.
