Life Cycle Assessment for Pavements with Low Rolling
Resistance
Reducing CO2 emissions through reduced rolling resistance TRB 2012
John Harvey - UC Davis Alissa Kendall - UC Davis Ting Wang - UC Davis In-Sung Lee - UC Davis Eul-Bum Lee, UC Berkeley Changmo Kim, UC Davis
Funding from:
Caltrans/UC Pavement Research
Center and UC Multi-Campus
Research Projects Initiative
Work presented is part of Miriam
• SP3 sub-task: Pavement LCA
• Swedish case studies done by VTI
• ZAG Slovenia evaluating road
network
Paper on this work under review
Journal of Cleaner Production
Report to be submitted to
Caltrans in March, 2012
The Pavement Life Cycle
Materials
End-of-Life
Maintenance &
Rehabilitation
Use
Construction
Materials
extraction and
production
Transportation
Onsite
equipment - Carbonation
- Lighting
- Heat Island
- Rolling resistance
- Leachate
Traffic
delay
A framework for analysis of policy cost-effectiveness
• Prioritizing Climate Change Mitigation Alternatives: Comparing Transportation Technologies to Options in Other Sectors
• Lutsey, N. (2008) Institute of Transportation Studies, University of California, Davis, Research Report UCD-ITS-RR-08-15
Supply Curve
• Compare keeping pavement smooth with:
• 1. Reduce vehicle-miles traveled; 2. Improve fleet fuel efficiency; 3. Reduce carbon content of fuel
Initial cost
Net costs =
initial cost +
direct
energy
saving
benefits
Bang for your buck metric:
$/ton CO2e vs CO2e reduction
Objectives of PPRC 4.26 Project
• Develop LCA model for state highway and local road networks – Initial models using available data sources
– Update as develop regional databases
• Use model to answer questions regarding GHG ($/ton CO2e) and fuel use (net reductions): – Rolling resistance (Roughness and macro-texture)
– Where to use in-place, plant, secondary recycling considering transportation costs, local materials
– Design life
– Alternative rehabilitation strategies
Basic Approach by UCPRC
• Divide network into categories (factorial)
• Apply factorial case studies results to network
• Sensitivity analyses
– Rolling resistance (smoothness and texture) for MIRIAM
– Materials (type, producing method, etc.)
– Hauling distance
– Traffic levels and congestion
– Traffic closure during construction
– Fleet composition (new vehicle technologies)
Constraint during model development
• Asphalt stays asphalt
• Concrete stays concrete
• Obtain industry critique with fewer commercial implications – (exc. RHMA vs HMA,
PCC vs CSA cement)
• Afterward, consider surface type change – Within LCCA framework
Factorial for LCA for California State and Local Networks
Factorials Possible Value
Road type Rural road; urban road
Road grades Flat road; mountainous road
Road access type Restricted access; unrestricted access
Traffic level Different levels of AADT and AADTT,
categorized
Pavement surface type
Asphalt pavement; cement concrete
pavement
Pavement surface characteristics
Different levels of IRI and MPD,
categorized
Treatment Different pavement treatment options
Models: Materials and construction
• Materials production and plant emissions: – Existing databases and studies
• Off-Road equipment – OFFROAD: California’s off-road equipment emission
inventory • On-Road equipment
– EMFAC: California’s on-road vehicles emission inventory
• Equipment and hours – CA4PRS: Caltrans construction schedule analysis
tool • Road user delay
– CA4PRS (not yet implemented)
Case Study 1 (KER-5): Asphalt overlay on rural/flat freeway
10 mile (16 km) segment in need of
rehab
Rural freeway
2 lanes, southbound
AADT: 34,000; ~35% trucks
Passenger Trucks
Inner Lane 77% 9%
Outer Lane 23% 91%
Compare:
- Do Nothing
-10 year rehab
-HMA, RHMA
Construction Scenarios: KER-5
HMA Type
Design life
Treatment Cross Section Smoothness
HMA 10 Years Mill & Overlay
45 mm (0.15’) Mill + 75 mm (0.25’) HMA with 15% RAP
Smooth Rehab
Less smooth Rehab
RHMA 10 years Mill & Overlay
30 mm (0.1’) Mill + 45 mm (0.15’) RHMA
Smooth Rehab
Less smooth Rehab
KER-5: Energy in Use Phase with 0 & 3% Traffic Growth
2.0E+7
2.2E+7
2.4E+7
2.6E+7
2.8E+7
3.0E+7
6.5E+8
7.0E+8
7.5E+8
8.0E+8
8.5E+8
9.0E+8
9.5E+8
1.0E+9
2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021
Eq
uiv
ale
nt
Ga
soli
ne (
L)
To
tal E
nerg
y (
MJ
)
Year
3% Traffic growth + Do Nothing + No fuel economy improvement
3% Traffic growth + Do Nothing + Fuel economy improvement
0% Traffic growth + Do Nothing + Fuel economy improvement
0% Traffic growth + Initial IRI=1.67 + Fuel economy improvement
0% Traffic growth + Initial IRI=1 + Fuel economy improvement
-1.6E+6
-6.3E+4
1.4E+6
2.9E+6
4.4E+6
5.9E+6
7.4E+6
-5.0E+7
0.0E+0
5.0E+7
1.0E+8
1.5E+8
2.0E+8
2.5E+8
Feedstock Energy Material Production
Construction Use
Eq
uiv
ale
nt
Gaso
lin
e (
L)
Tota
l E
nerg
y S
avin
g C
om
pa
red
to D
o N
oth
ing
(MJ
)
Phase
3% Traffic growth: Smooth Rehab compared to Do Nothing
3% Traffic growth: Less Smooth Rehab compared to Do Nothing
0% Traffic growth: Smooth Rehab compared to Do Nothing
0% Traffic growth: Less Smooth Rehab compared to Do Nothing
KER-5 (RHMA): 10-year life cycle energy savings compared to “Do Nothing”
USLCI Athena
Stripple Ecoinvent
0
-1.6E+6
-6.3E+4
1.4E+6
2.9E+6
4.4E+6
5.9E+6
7.4E+6
-5.0E+7
0.0E+0
5.0E+7
1.0E+8
1.5E+8
2.0E+8
2.5E+8
2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022
Eq
uiv
ale
nt
Gaso
lin
e (
L)
Cu
mm
ula
tive E
nerg
y S
avin
g C
om
pare
d t
o
Do N
oth
ing
(M
J)
Year
3% Traffic growth: Smooth Rehab compared to Do Nothing
3% Traffic growth: Less Smooth Rehab compared to Do Nothing
0% Traffic growth: Smooth Rehab compared to Do Nothing
0% Traffic growth: Less Smooth Rehab compared to Do Nothing
KER-5 (RHMA): Cumulative life cycle energy compared to “Do Nothing”
Construction
0
Case Study 2 (LA-5): Concrete CPR B on rural/flat freeway
10 mile (16 km) segment in need of rehab
Rural freeway
4 lanes, southbound
AADT: ~80,000; ~25% trucks
Cars Trucks IRI Lane 1 (Inner) 38% 0.2% 3 Lane 2 34% 8% 3 Lane 3 16% 42% 3.5 Lane 4 (Outer) 13% 49% 4
Compare:
- Do Nothing
- 10 year CPR B
-Type III, CSA cement
Construction Scenario (LA-5)
Treatment Design life
Material Smoothness
CPR B with 3% slab replacement and grinding the entire lane
10 yrs
Type III Rapid Strength Cement (3.2 Mpa in 4 hours)
Smooth Rehab (-2σ)
Medium Smooth Rehab (mean)
Less Smooth Rehab (+2σ)
Calcium Sulpho-Aluminate (CSA) Cement (2.8Mpa in 4 hours)
Smooth Rehab (-2σ)
Medium Smooth Rehab (mean)
Less Smooth Rehab (+2σ)
-1.6E+6
3.4E+6
8.4E+6
1.3E+7
1.8E+7
-5.0E+7
5.0E+7
1.5E+8
2.5E+8
3.5E+8
4.5E+8
5.5E+8
6.5E+8
2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022
Eq
uiv
ale
nt G
aso
lin
e (L
)
Cu
mm
ula
tiv
e E
ner
gy
Sa
vin
g C
om
pa
red
to
Do
No
thin
g (M
J)
Year
3% Traffic growth: Smooth Rehab compared to Do Nothing
3% Traffic growth: Medium Smooth Rehab compared to Do Nothing
3% Traffic growth: Less Smooth Rehab compared to Do Nothing
0% Traffic growth: Smooth Rehab compared to Do Nothing
0% Traffic growth: Medium Smooth Rehab compared to Do Nothing
0% Traffic growth: Less Smooth Rehab compared to Do Nothing
LA-5 (Type III PCC): Cumulative life cycle energy savings compared to “Do Nothing”
Construction
Case Study 3 (BUT-70): Asphalt overlay on rural/flat highway
5 mile (8 km) segment in need of rehab
Rural highway
2 lanes, westbound
AADT: 3,200; ~15% trucks
Cars Trucks IRI
Lane 1 (Inner) 61% 8% 3.8
Lane 2 39% 92% 3
Compare:
- Do Nothing
-10 year rehab
-HMA, RHMA
-4.7E+5
-2.7E+5
-6.9E+4
1.3E+5
3.3E+5
-1.5E+7
-1.0E+7
-5.0E+6
0.0E+0
5.0E+6
1.0E+7
1.5E+7
2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022
Eq
uiv
ale
nt G
aso
lin
e (L
)
Cu
mm
ula
tiv
e E
ner
gy
Sa
vin
g C
om
pa
red
to
Do
No
thin
g (M
J)
Year
3% Traffic growth: Smooth Rehab compared to Do Nothing
3% Traffic growth: Less Smooth Rehab compared to Do Nothing
0% Traffic growth: Smooth Rehab compared to Do Nothing
0% Traffic growth: Less Smooth Rehab compared to Do Nothing
BUT-70 (RHMA): Cumulative life cycle energy savings compared to “Do Nothing”
Construction
0
Case Study 4 (IMP-86): Concrete CPR B on rural/flat highway
5 mile (16 km) segment in need of rehab
Rural highway
2 lanes, southbound
AADT: ~11,200; ~29% trucks
Cars Trucks IRI Lane 1 (Inner) 76% 8% 2.5 Lane 2 24% 92% 2.7
Compare:
- Do Nothing
- 10 year CPR B
-Type III, CSA cement
-3.1E+5
-6.3E+4
1.9E+5
4.4E+5
6.9E+5
9.4E+5
1.2E+6
-1.0E+7
0.0E+0
1.0E+7
2.0E+7
3.0E+7
4.0E+7
2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022
Eq
uiv
ale
nt G
aso
lin
e (L
)
Cu
mm
ula
tiv
e E
ner
gy
Sa
vin
g C
om
pa
red
to
Do
No
thin
g (M
J)
Year
3% Traffic growth: Smooth Rehab compared to Do Nothing
3% Traffic growth: Medium Smooth Rehab compared to Do Nothing
3% Traffic growth: Less Smooth Rehab compared to Do Nothing
0% Traffic growth: Smooth Rehab compared to Do Nothing
0% Traffic growth: Medium Smooth Rehab compared to Do Nothing
0% Traffic growth: Less Smooth Rehab compared to Do Nothing
IMP-86 (Type III PCC): Cumulative life cycle energy savings compared to “Do Nothing”
Construction
Conclusions
• LCA model is powerful tool to estimate net energy use and GHG from maintenance and rehabilitation activities
• Case studies to date demonstrate potential for high net energy/GHG savings on high-volume routes from improvements in roughness and texture (asphalt)
• Construction quality of smoothness critical
Next Steps • Complete work with California cement and
asphalt industries on inventories
• Develop Use phase models for congested traffic
• Complete case studies and sensitivity for factorial
• Include results in Caltrans smoothness specs
• Implement into Caltrans policy
– Initial GHG equation for pavement treatments being implemented in PMS
Questions?