steven e. polzin, phd
TRANSCRIPT
Steven E. Polzin, PhD. Center for Urban Transportation Research University of South Florida April 2012
Fundamentals on Interpreting NHTS Data
“If you torture the data long enough, nature will confess.”
Ronald Coase – 1991 Noble Prize in Economics
“If you torture the data long enough you can make it confess to anything.”
Alan Pisarski – No Noble Prizes
Travel Trends
0
50
100
150
200
250
300
350
400
450
1977 1983 1990 1995 2001 2008
Ann
ual H
ours
per
Per
son
Travel Time per Capita
0
0
0
0
0
0
0
0
0
0
1969 1977 1983 1990 1995 2001 2008
Ann
ual V
MT
VMT per Person
-
500,000
1,000,000
1,500,000
2,000,000
2,500,000
1969 1977 1983 1990 1995 2001 2008
VMT in Millions
-
0.50
1.00
1.50
2.00
2.50
1969 1977 1983 1990 1995 2001 2008
PMT/VMT
PMT and VMT per Capita by Age
0
5000
10000
15000
20000
25000 2001 Per Capita VMT 2001 Per Capita PMT
2008 Per Capita VMT 2008 Per Capita PMT
The NHTS Transit Sample
Select Metro Areas Unweighted Transit Trips
Share of National Transit Sample
Weighted Share of National Transit Sample
Share of National
Population
UZA Share of NTD
National Trips
Boston--Worchester--Lawrence, MA--NH--ME--CT 60 0.7% 2.9% 2.0% 3.7%
Charlotte--Gastonia--Rock Hill, NC--SC 7 0.1% 0.1% 0.6% 0.2%
Houston--Galveston--Brazoria, TX 175 2.1% 1.0% 1.6% 0.8%
Louisville, KY--IN 0 0.0% 0.0% 0.3% 0.2%
Minneapolis--St. Paul, MN--WI 11 0.1% 0.4% 1.1% 0.9% New York--Northern New Jersey--Long Island, NY--NJ--CT--PA 2552 29.9% 33.1% 7.3% 40.5%
Phoenix--Mesa, AZ 237 2.8% 0.3% 1.4% 0.7%
Salt Lake City--Ogden, UT 20 0.2% 0.5% 0.6% 0.3%
Tampa--St. Petersburg--Clearwater, FL 59 0.7% 0.3% 0.9% 0.3%
Trip Rate and Length
1067
1054
1371
1568
1449
1385
9.47 8.68 9.29 9.00
10.78 9.52
0
5
10
15
20
0
200
400
600
800
1000
1200
1400
1600
1800
1977 1983 1990 Adj. 1995 2001 2008
Trip
Len
gth
Ann
ual T
rips
per
Per
son
5+
NPTS and NHTS Work Trip Walking Mode Shares
1969 5.00%
1977 4.60% 1983
4.10% 1990 3.70%
1995 2.60%
2001 2.81%
2008 2.82%
1983 4.50% 1990
4.00%
1995 2.30%
2001 2.92%
2008 3.03%
0%
1%
2%
3%
4%
5%
6%
1969
19
70
1971
19
72
1973
19
74
1975
19
76
1977
19
78
1979
19
80
1981
19
82
1983
19
84
1985
19
86
1987
19
88
1989
19
90
1991
19
92
1993
19
94
1995
19
96
1997
19
98
1999
20
00
2001
20
02
2003
20
04
2005
20
06
2007
20
08
2009
Perc
ent W
alki
ng to
Wor
k
Work Trip "Usual Mode"
Work Trip Actual Mode
Walk is 10.95% of all trips in 2008
8.90%
6.40%
5.30%
4.70% 4.99% 4.60%
3.56% 3.67%
3.68%
3.40%
2.70% 2.70% 2.20% 1.81% 1.56%
1.92%
1.76%
5.11% 5.05%
5.13%
0%
1%
2%
3%
4%
5%
6%
7%
8%
9%
10%
Perc
ent o
n Tr
ansi
t
Census/ACS Journey to Work, Usual Mode
NPTS/NHTS Work Trips, Survey Day
NPTS/NHTS All Trips
NHTS 2001 Adjusted
NHTS Work Trip, Work Trip Usual Mode
Transit Mode Share Trends
Vehicle Occupancies - NHTS
1.40 1.30 1.30
1.20 1.20 1.20 1.13
1.90 1.90
1.80 1.70
1.59 1.64
1.67
0.80
1.00
1.20
1.40
1.60
1.80
2.00
2.20
1969 1974 1979 1984 1989 1994 1999 2004 2009
Occ
upan
cy
Work Trip
All Trips
Carpooling Mode Share (ACS)
20.4% 19.7%
13.4% 12.2%
10.7%
0%
5%
10%
15%
20%
25%
1970 1980 1990 2000 2008
Perc
ent C
arpo
olin
g to
Wor
k
Vehicle Availability
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1969 1974 1979 1984 1989 1994 1999 2004 2009
Vehi
cles
per
Vehicles per worker
Vehicles per person 16 and older
Vehicles per person
Vehicles per driver
Declining Zero-Vehicle Households?
0%
5%
10%
15%
20%
25%
1960 1970 1980 1990 2000 2010
Per
cent
NPTS/NHTS Census ACS
Source: CUTR analysis of NHTS ,NPTS,U.S. Census Bureau and 2002-09 ACS
Household Vehicle Ownership Distribution Household Percents
National Household Vehicle Ownership Distribution, 2009
HH Vehicles Number of Adults in HH 1 2 3 4 5+ All
0 5.79% 2.28% 0.38% 0.19% 0.05% 8.69%
1 20.40% 10.18% 1.31% 0.33% 0.06% 32.28%
2 3.66% 29.04% 2.92% 0.62% 0.08% 36.32%
3 0.74% 9.06% 3.72% 0.78% 0.09% 14.39%
4 0.21% 2.58% 1.54% 0.82% 0.13% 5.30%
5+ 0.14% 1.40% 0.82% 0.49% 0.17% 3.02%
All 30.96% 54.54% 10.69% 3.23% 0.58% 100.00%
20.66% More cars than adults
54.16% Cars equals adults
16.50% Fewer cars than adults
8.69% Zero cars
Who is Using
Transit?
Transit Market Share by Car Availability
32.5%
15.6%
3.3% 13.7%
14.4%
7.2%
13.4%
2008
0 Cars, 1 or More
0 Cars, 0 Workers
2+ More Workers than Autos
1 More Worker than
Cars is Greater than Workers
Cars =
1 Car, 1
34.9%
9.7%
8.2% 15.4%
11.2%
9.4%
11.2%
2001
0 Cars, 1 or More
Workers
0 Cars, 0 Workers
2+ More Workers than
Autos 1 More Worker than
Cars is Greater than Workers
Cars = Workers
1 Car, 1 Worker
0 car household riders make up 44.6% of riders
0 car household
riders make up 48.1% of riders
0
5
10
15
20
25
30
0 Cars, 1 or More Workers
0 cars, 0 Workers
2+ More Workers than
Autos
1 More Worker than
Autos
Cars is Greater Than
Workers
Cars = Workers
1 Car, 1 Worker
Mod
e Sh
are
Perc
ent
2001
2008
Transit Mode Share by Vehicle Availability
Shortage of Vehicles
Transit Mode Share by Income
5.98
2.31
1.05
1.92
5.32
1.38
0.91
1.57
4.98
1.57
1.07
1.81
0
1
2
3
4
5
6
7
Under $15,000 $15,000-$50,000 $50,000+ Totals
Mod
e Sh
are
Perc
ent
2008
2001
1995
Transit Mode Share by Home Ownership Status
4.93
0.81
4.25
0.73
4.57
0.9
0
1
2
3
4
5
6
Renter Owner
Mod
e Sh
are
Perc
ent
2008
2001
1995
Transit Mode Share by Immigration Status
0.12 0.39 0.45 1.11 1.15
3.40
1.56
0.44 0.85 0.87
2.67
1.87
7.69
5.20
0
1
2
3
4
5
6
7
8
9
Outside MSA
Under 250 250-500 500-1,000 1,000-3,000 3,000+ All
Mod
e Sh
are
Perc
ent
Born in US Born Outside USA
Mode Speeds
29.1
13.7
10.1
8.7
11.5
11.2
11.2
10.1
10.8
10.9
10.3
11.8
0
5
10
15
20
25
30
35
40
Not in MSA or CMSA
MSA of Less than 250,000
MSA of 250,000 - 499,999
MSA of 500,000 - 999,999
MSA or CMSA of 1,000,000 - 2,999,999
MSA or CMSA of 3 million or more
Spee
d M
PH
Metro Area Size
2008 Transit 2008 POV 2001 Transit 2001 POV
Transit and Elderly Person Trips per Day by Age
Transit Mode Share by Age
Share of Transit Trips by Age Groups
0.0
1.0
2.0
3.0
4.0
5.0
5-14 15-24 25-34 35-44 45-54 55-64 65-74 75-84 85+
Ave
rage
Tri
ps p
er D
ay
Age Group
0.0% 0.5% 1.0% 1.5% 2.0% 2.5% 3.0% 3.5%
5-14 15-24 25-34 35-44 45-54 55-64 65-74 75-84 85+
Tran
sit M
ode
Shar
e
Age Group
5-14, 6.5%
15-24, 21.3%
25-64, 64.0%
65+, 8.2%
Distribution of Transit Trips by Wait Time for Selected Transit Markets
34.4
%
28.6
%
44.4
%
41.4
%
31.3
%
30.3
%
33.1
%
21.5
%
17.5
%
25.7
%
0%
20%
40%
60%
80%
100%
15+ minutes 10 - 14 minutes 5 - 9 minutes Under 5 minutes
Distribution of Transit Trips by Wait Time for Income-Based Markets
12.0% 18.5% 32.4% 32.2%
23.4%
31.1%
38.8% 34.0% 23.3%
26.4%
17.9% 21.3% 41.4%
24.0% 11.0% 12.4%
0%
20%
40%
60%
80%
100%
Under $15,000 (low-income)
$15,000-$49,999 (middle low-
income)
$50,000-$99,999 (middle high-
income)
$100,000+ (high-income)
15+ minutes 10 - 14 minutes 5 - 9 minutes Under 5 minutes
Distribution of Transit Trips by Last Access Mode for Income-Based Markets
94.2% 90.7% 88.0% 78.9%
3.9% 6.8% 5.4%
9.5%
0%
20%
40%
60%
80%
100%
Under $15,000 (low-income)
$15,000-$49,999 (middle low-income)
$50,000-$99,999 (middle high-income)
$100,000+ (high-income)
Other Bike POV Transit Walk
Cumulative Distance of Household to Bus Route
0%10%20%30%40%50%60%70%80%90%
100%
<= .1
5.3
1 - .
45.6
1 - .
75.9
1 - 1
.05
1.21
- 1.
351.
51 -
1.65
1.81
- 1.
952.
11 -
2.25
2.41
- 2.
552.
71 -
2.85
3.01
- 3.
153.
31 -
3.45
3.61
- 3.
753.
91 -
4.05
4.21
- 4.
354.
51 -
4.65
4.81
- 4.
954.
96 -
5.10
5.11
- 13
>13
- 21
>21
- 29
>29
- 37
>37
- 45
>45
- 52
>52
- 60
>60
- 68
>68
- 76
>76
- 84
>84
- 92
Per
cent
of H
ouse
hold
s
Distance in Miles (note scale break at 5.11 miles)
Almost 50 % of households nationally live within 1/2 mile of a bus route
Bus trip Mode Share by Household Distance
0%
1%
2%
3%
4%
5%
6%
7%
<= .15 .16 - .30 .31 - .45
Bus
Mod
e S
hare
Miles
Bus All TripsBus Work Trips
NHTS - A FIX FOR DATA ADDICTS AND INOCULATION AGAINST UNINFORMED DECISIONS
27