Impacts of Roadway and Traffic Characteristics on Air Pollution Risks for Bicyclist
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Transcript of Impacts of Roadway and Traffic Characteristics on Air Pollution Risks for Bicyclist
TREC Webinar22 April, 2015
Impacts of Roadway and Traffic Characteristics on Air Pollution Risks for Bicyclists
Alex BigazziMiguel FigliozziJim PankowWentai Luo
Health Effects of Bicycling
• Health impact studies for walking & biking have shown that physical activity benefits outweigh crash & air pollution risks by an order of magnitude or more
• Still, we can & should reduce pollution risks
2Urban Bicyclists' Pollution Uptake
Framework
3
Vehicle Emissions
Air Quality
Traveler ExposureInhalation
Uptake Health Effects
Bicyclists' Pollution Uptake
Outline
1. Exposure concentrations
2. Ventilation & inhalation dose
3. Pollutant uptake
4. Applications for transportation planning and design
4Bicyclists' Pollution Uptake
Bicyclists’ Exposures
6
0 5 10 15 20
Ultrafine PM
Fine PM
Coarse PM
Black Carbon
CO
VOC
NO2
# studies measuring on-road bicyclists’ exposure concentrations
Pollutant 42 studies
Bicyclists' Pollution Uptake
9k – 94k pt/cc
0.5 – 13 ppm
5 – 88 µg/m3
Modal Comparisons of Exposure
– Is this actionable information?
Context-dependent results– Bicyclists lower if separated
7Bicyclists' Pollution Uptake
vsvs
High-Traffic/Low-Traffic Routes
8Bicyclists' Pollution Uptake
-50%
0%
50%
100%
150%
200%
250%
CO VOC UFP PM2.5 PM10 BC
Expo
sure
Inc
reas
e on
H
igh-
Traf
fic R
oute
s
N=6 N=11 N=8 N=6 N=3 N=5
PSU Bike Exposure Research
9Urban Bicyclists' Pollution Uptake
How can we reduce exposure risks for bicyclists?
Results: VOC Exposure Models
• +2% per 1,000 ADT
• +20-30% in stop-and-go riding
• Off-street path +300% in industrial
corridor
12Bicyclists' Pollution Uptake
13
Parallel Path Comparison
Bicyclists' Pollution Uptake
E Burnside St. SE Ankeney St.
N Williams Ave. NE Rodney Ave.
Naito Pkwy. Riverside Path
Ventilation and Exercise
15Bicyclists' Pollution Uptake
50 100 150 200 250 Watts
Vent
ilatio
n (
liter
/min
) 75
50
25
Ventilation is strongly related to exertion level
Ventilation & Bicycle Studies
16
57 studies assessbicyclists’ exposure
Ignored38
Constant16
Assumed/Modeled
15Measured
1
Variable3
Modeled 2
Measured1
Ven
tila
tio
n:
Urban Bicyclists' Pollution Uptake
Bicyclist Ventilation
17Urban Bicyclists' Pollution Uptake
0
1
2
3
4
5
0 5 10 15 20Ratio
of
Bic
ycle
/Mot
oriz
ed
Trav
eler
Ven
tilat
ion
Bicycle Speed (mph)
AllMenWomen
Modal Comparisons of Dose
18Urban Bicyclists' Pollution Uptake
-100%
-80%
-60%
-40%
-20%
0%
20%
40%
60%
Pedestrian Car/Taxi Bus
Dif
fere
nce
fro
m B
icyc
list
Dos
e
COUFPPM2.5
N
(3)
(3)
(5)
PSU Research Findings
• 4-8% increase in ventilation per 10 W
• Mean lag ~50 sec
• Highly variableon-road
19Bicyclists' Pollution Uptake
0 50 100 150
0.0
0.2
0.4
0.6
0.8
Seconds workload lagged
Cum
ulat
ive im
pact
on ve
ntila
tion
(%
SubjecABCPooled
% Δ
vent
ilatio
n pe
r W
Seconds lag
Bicyclist Uptake Studies
2 studies of biomarkers:
• VOC: blood & urine– Urban bikers > rural bikers
• BC: induced sputum– Bicyclists > transit riders
21Bicyclists' Pollution Uptake
Breath BiomarkersExhaled breath is a good proxy for
blood concentrations of VOC
22Bicyclists' Pollution Uptake
alphaszenszor.com
VOC in blood
1) Local roads
Pre Breath
Post Breath
PSU On-Road Sampling
20-30 minutes, 3-5 milesExposure & breath VOC
Paired subjects
23Bicyclists' Pollution Uptake
Pre Breath
Post Breath
2) Major arterials
Breath and Exposure Concentrations
0 1 2 3
Breath
Exposure
Concentration (normalized to Park)
Toluene
Major arterials
Local streets
24Bicyclists' Pollution Uptake
Breath Sampling Results
• The breath sampling method works– Exposure predicts breath concentrations– Δ Breath ~ ½ Δ Exposure
• 10-60% higher on major arterials than local streets– Traffic impact (over BG) 3-5x greater on
major arterials than local streets
25Urban Bicyclists' Pollution Uptake
Explained variance in breath BTEX
26Bicyclists' Pollution Uptake
0%
10%
20%
30%
40%
50%
Measured variables Modeled variables
Exposure
Ventilation
Exposure variability
Weather variables
Road & traffic
variables
Exercise and Uptake
• Ventilation/inhalation rate: 2-5x higher
• PM uptake: ≥2-5x higher
• VOC uptake: 1.5-2x higher
27Bicyclists' Pollution Uptake
Route Choice
• Detour to reduce inhalation dose if:– <46% longer than minor arterial route– <123% longer than major arterial route
• Inhalation doses +20-30% per 1% grade
29Bicyclists' Pollution Uptake
?
Comparison with Preferences
30Bicyclists' Pollution Uptake
Will bicyclists naturally minimize inhaled dose over a trip?
Bike boulevard
or
neighborhood greenway
Bike lane
Minor arterial (no bike lane)
Major arterial (no bike lane)
• Slightly over-avoid
• Balance on collectors (6-10k ADT) • Under-avoid arterials
• Greatly over-avoid
vs.
vs.
vs.
Inhalation and Stops
31Urban Bicyclists' Pollution Uptake
0
100
200
300
400
500
600
6 8 10 12 14 16 18
Cru
ise-
equ
ival
ent
exce
ss
ven
tila
tio
n (
ft)
Cruise speed (mph)
Inhalation and Speed
32Bicyclists' Pollution Uptake
0
50
100
150
200
250
300
0 4 8 12 16
Ven
tila
tion
(l/
km)
Speed (mph)
0% Grade2% Grade
Bikeway Design ConsiderationsBike lane • Higher-traffic streets
• Some lateral separation• Dedicated lane reduces stops in
congestion
Cycle track • Higher-traffic streets• More lateral separation
Bike boulevard
• Low-traffic streets• Additional benefits from traffic calming• Fewer stops reduces doses
Off-street path
• Low exposure (nearby industry?)• Fewer stops reduces doses
33Bicyclists' Pollution Uptake
Take-Away Principles
1. Bicyclist Exposure a) Many different pollutantsb) Traffic, weather, and land-use all important c) Benefits of separation from traffic
2. Bicyclist Inhalationa) Varies greatly with workload (speed, grade)b) Breath response spread out over 1-2 min
3. Bicyclist Uptakea) For particles, highly sensitive to breathingb) For some gases, more sensitive to exposure &
duration
34Bicyclists' Pollution Uptake
Future Work
• Abstraction for HIA & CBA• Characterizations of urban bicyclists • Similar study for pedestrians• Crowd-source pollution data
35Bicyclists' Pollution Uptake
Questions?
36Bicyclists' Pollution Uptake
Acknowledgments• Miguel Figliozzi, Jim Pankow, Wentai Luo• NITC, City of Portland, Portland Metro, NSF, OTREC
Steady-state biking work
38Bicyclists' Pollution Uptake
0
50
100
150
200
250
0 2 3 5 6 8 9 11 13 14 16
Wor
kloa
d (W
)
Speed (mph)
Rolling Resistance Drag 1% Grade