Civil Engineering Reference
In-Depth Information
Table 6.17 The impact of employment changes on traf
c congestion
Area type
Travel time tax
a
Total employment
(thousands)
2006
2010 % Change
2006 (%)
2010 (%) % Change
Most congested metro area
(Los Angeles)
5,695
5,170
9.2
43.7
35.4
19.0
−
−
Top 100 metros
93.3
87.9
5.8
11.1
9.7
12.7
−
−
National
136.9
130.7
−
4.5
NA
NA
NA
Source
Reference [
10
], INRIX, p. A-1
a
Per INRIX de
nition = travel time in excess to free-
fl
ow travel time expressed as % of free-
fl
ow
travel time
Table 6.18 Elasticity of
VMT regarding gas prices
2007
2008
%
$/Gal.
$2.80
$3.25
+16
VMT (Billion)
483
469
−
2.9
Source
Reference [
12
], INRIX 2009, p. ES-2
The elasticity of VMT with respect to gas prices can be calculated as
¼
2
9
%
:
E
VMT
re
:
Price
%
¼
0
18
ð
6
1
Þ
:
:
16
finding is in the range of driving elasticity (the elasticity of VMT with
respect to gasoline prices) values of
This
0.15 to
0.20 values reported by Gillingham
−
−
[
11
] for the 2005
-
2008 period in California.
6.3.1 Rate of VMT Growth per Capita Is Likely to Decrease
in the Future
The trends in the factors that generated strong VMT growth in the second half of
the 20th century have reached saturation points and have slowed down considerably
since the beginning of the new millennium. Including:
The share of the women in the work force has leveled off to 60 %, and the share
of women with driving licenses approaches 85 % [
13
]
Increasing household incomes are unlikely to result in corresponding increases
in car ownership rates since car ownership rates have reached saturation levels
