Health Impacts of Increased Physical Activity from Changes in Transportation Infrastructure: Quantitative Estimates for Three Communities
Table 2
Summary of findings, with 95% confidence intervals based on uncertainty in relative risk parameters.
Built environment variables
BRRC
Winterville
Sparta
Before
After
Change
Before
After
Change
Before
After
Change
Walkability score
−3.61
0.96
+4.57
—
—
—
—
—
—
Sidewalk density (km/km2)
—
—
—
0.8
3.8
+3.0
—
—
—
PEF (categorical)
—
—
—
—
—
—
Low
Medium
+1
Walking outcomesa
Before
After
Change
Before
After
Change
Before
After
Change
No walking (percent)
40.7%
40.7%
0%
84.3%
83.4%
−0.9%
85.4%
82.4%
−3.0%
1–149 min/week (percent)
41.5%
21.2%
−20.3%
12.3%
12.9%
+0.6%
12.1%
14.6%
+2.5%
150+ min/week (percent)
17.8%
38.1%
+20.3%
3.4%
3.6%
+0.2%
2.5%
3.0%
+0.5%
Ave. walk time (min/week)
13.1
30.4
+17
12.5
13.2
+0.7
10.4
12.6
+2.2
Health outcomesa
Years after construction
Years after construction
Years after construction
10
20
40
10
20
40
10
20
40
Avoided premature mortality
4.9 (1.8–7.7)
8.5 (3.1–13.3)
14.3 (5.2–22.6)
0.3 (0.1–0.5)
0.5 (0.2–0.9)
0.9 (0.3–1.4)
0.3 (0.1–0.4)
0.4 (0.2–0.7)
0.5 (0.2–0.8)
Avoided cases of CHD
1.9 (1.6–2.1)
3.7 (3.1–4.1)
6.1 (5.1–6.7)
0.0 (−0.1–0.1)
0.0 (−0.1–0.2)
0.0 (−0.2–0.3)
0.0 (−0.1–0.2)
0.0 (−0.2–0.3)
0.0 (−0.2–0.3)
Avoided cases of type 2 diabetes
4.9 (2.6–7.6)
9.4 (5.1–14.5)
15.6 (8.3–24.1)
0.5 (0.0–1.0)
1.0 (−0.1–1.9)
1.5 (−0.2–2.9)
0.4 (0.0–0.7)
0.6 (−0.1–1.2)
0.8 (−0.1–1.6)
Avoided cases of hypertension
11.8 (4.5–16.7)
21.4 (8.4–30.1)
32.1 (12.3–45.1)
1.5 (0.4–2.5)
2.7 (0.6–4.5)
4.0 (0.9–6.9)
0.9 (0.2–1.5)
1.4 (0.3–2.4)
1.8 (0.4–3.2)
Avoided cases of stroke
1.1 (0.0–1.6)
1.8 (−0.1–2.9)
2.1 (−1.1–4.0)
0.1 (−0.1–0.3)
0.2 (−0.2–0.6)
0.3 (−0.3–0.8)
0.1 (−0.1–0.3)
0.2 (−0.1–0.4)
0.2 (−0.2–0.5)
Economic outcomes
Years after construction
Years after construction
Years after construction
10
20
40
10
20
40
10
20
40
Net present value (2012 USD)
33.4M (10.8–53.7)
50.4M (18.4–79.0)
66.8M (26.8–103)
−5.1M (−6.5–−3.9)
−3.9M (−5.9–−2.1)
−2.9M (−5.3–−0.6)
1.4M (0.1–2.5)
2.2M (0.5–3.7)
2.6M (0.7–4.2)
Benefit-cost ratio
10.6 (4.1–16.5)
15.5 (6.3–23.7)
20.2 (8.7–30.6)
0.3 (0.1–0.5)
0.5 (0.2–0.7)
0.6 (0.3–0.9)
3.0 (1.1–4.6)
4.1 (1.7–6.3)
4.7 (2.1–7.1)
Time for B : C to exceed 1
1 year (1-2 years)
Benefits do not exceed costs
3 years (2–9 years)
Estimates of walking for transportation after construction in Winterville do not add to 100% due to rounding. bFor all health and economic outcomes, 95% confidence intervals are estimated using the lower and upper bounds of the relative risk parameters as noted in Table 1. c5% discount rate assumed.
