Construction TRB 2007 Final Revised

8/3/2019 Construction TRB 2007 Final Revised

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UC Davis-Caltrans Air Quality Project 1

Construction Emissions: Using Project Data to

Improve Regional Inventories

Douglas Eisinger, Ph.D.

Deb Niemeier, Ph.D., P.E.

UC Davis-Caltrans Air Quality Project

Presented at the 86th Annual Meeting of theTransportation Research Board, Workshop 135

Guidelines on Conducting Project Level Air

Quality AnalysisWashington, D.C. January 21, 2007


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Outline

1. Motivation: Need Local Activity Data

2. Setting the Context: Example Project

3. Top-Down Regional Emissions

4. Bottom-up Regional Emissions Number and type of construction projects per year

Equipment and use per project Emissions

5. Sacramento Example: Bottom-up Inventory

6. Comparison: Top-Down vs. Bottom-up

7. Some Observations8. Conclusions


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1. Motivation: Need Local Activity Data

Powerpoint From Caltrans Training Exercise


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2. Setting the Context: Example Project

1.7 mile long I-80 auxiliary lane addition in Sacramento

6 month project, four construction stages: Land clearing

Roadway grading and excavation

Drainage/utilities/sub-grade

Paving


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Sacramento Project:Year 2008 NOx Emissions

Analysis inputs Total disturbed project area: 8 acres

Soil moved: 300 yd3 per day (imports and exports)

Model-Assigned Equipment by phaseSign

Boards Bulldozer Scrapper Excavator Grader

Rubber

tired

loader Compactor Trencher Paver

Paving

Equip Roller

Clearing 3 1 1

Grading 3 1 1 1 1

Drainage/

Utilities/

Sub-grade

3 1 1 1 1

Paving 3 1 1 2


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Modeled with Sacramento area air district tool

Total project NOx emissions: 3.5 tons

But emissions would be about 10-15% lesswith solar sign boards

(instead of diesel-powered sign boards)

Lets look at building a regionalinventory

Sacramento Project:Year 2008 NOx Emissions


7/21UC Davis-Caltrans Air Quality Project 7

3. Sacramento NOx Emissions: Top-Down

Diesel Construction (19 tpd)

All Other Sources (219 tpd)

Diesel-powered construction is 8% of annual averageNOx emissions (2008)

Basis: regional equipment populations, activity, and

OFFROAD emission factors

Note: transportation construction is not separated



Top Down: Estimating TransportationConstruction NOx

Need to disaggregate total construction emissions

Possible approaches Road construction PM emissions are 58% of all

construction and demolition PM emissions

ARB construction equipment population surveys: SIC Group 161 (highway / street construction) is 12%

SIC Group 162 (includes bridge, tunnel, elevated highway) is 38%

SIC 161 + 162 equal 50% of all construction equipment

Possible range 12-58% of all construction =transportation construction



4. Bottom Up Regional Emissions

Data needs: Equipment and use per project

Number of construction projects

Emission factors



Equipment and Use Per Project (1 of 2):California Statewide Data

UCD created data set ofCaltrans projects for

years 2000-2005

Established six majorconstruction categories

Project Type N

1. Resurface ExistingHighway 38% 716

2. Pavement Rehabilitation /Widening 24% 453

3. Construct Freeway / ExtraLane 11% 215

4. Landscaping 11% 215

5. Construct median, thriebeam barrier 9% 170

6. Construct, ReconstructBridge 6% 118



Equipment and Use Per Project (2 of 2)

Collected daily reports(diaries) for 30 projects

Built data set of equipment

activity by project



Year 2008 NOx Emissions for Average Project

Equipment Category Hrs/Project NOxEFs* Tons/Project % ofNOx

Rollers 688 390 0.296 11%

Rubber Tire Loaders 376 593 0.246 9%

Graders 257 734 0.208 8%

Generator Set 278 658 0.202 8%

Scrapers 113 1,494 0.187 7%

Tractors / Loaders /Backhoes 436 360 0.173 7%

Subtotal for top six 2149 1.3 50%Total (entire project) 6149 2.7 100%

*EFs: gms/equip piece/hr (from OFFROAD2007)

Wide range by project type:

0.3

10.7 tons



5. Sacramento Example: Bottom-Up Inventorya. Number of Projects

Caltrans data: 57 Caltrans projects / year

SACOG data: 63 other transportation projects / year

Total: 120 projects per year

Source: average of 2004-2006 project datafrom Caltrans and SACOG.



5. Sacramento Example: Bottom-Up Inventoryb. 2008 Regional NOx Emissions Estimate

Ave. project:

2.7 tons NOx

X

120

projects/yr

=289 NOxtons/yr

Ave. project:253 days

=1.1 NOx

tons/day



Sacramento Example: Caveats

Lots of assumptions! Caltrans data set is representative

Other Caltrans projects are similar to top six categories

SACOG projects are similar to Caltrans projects

Average project represents typical project mix for a given year

Main point illustrate concept,give sense of scale to emissions

Ave. project:2.7 tons NOx

X

120projects/yr

=289 NOxtons/yr


= 1.1 NOxtons/day

Ave. project:2.7 tons NOx

X

120projects/yr

=289 NOxtons/yr


= 1.1 NOxtons/day



6. Comparison: Top-Down vs. Bottom-UpSacramento 2008 NOx Emissions

Top-Down (OFFROAD2007)

All NOx = 238 tpd

All construction = 19 tpd

IF THEN

58% = trans. 11 tpd(PM %)

50% = trans. 9.5 tpd(SIC 161 + 162)

12% = trans. 2.3 tpd(SIC 161 only)

Bottom-Up1.1 tpd = trans.

In this illustration, top-downemissions are 2-10 X higher

than bottom-up

0

2

4

6

8

10

12

58% of Top Down 50% of Top Down 12% of Top Down Bottom-Up Method



7. Some Observations

Activity varies by project type in Caltrans data

Project duration: 181 394 days Total projectNOx emissions: 0.3 10.7 tons

Caveat: data set needs to be expanded to better representindividual project types

Main point: estimating project emissionsrequires activity data specific to project type



Some Observations: Off-Road Modeling Not asMature as On-Road Modeling

Nov. 2006: California ARB releases OFFROAD2007 8% less equipment than prior model

Construction equipment useful life doubled from prior model

Equipment Old New Diff

Graders 6510 6178 - 5%

Tractors/Loaders/Backhoes 33,990 28,213 - 17%

Pavers 2616 2710 + 4%

Example year 2000 equipment populations (statewide)



8. Conclusions

Activity assumptions are central to emissions estimates

Inventory tools are still in early development stages

Bottom-up can quality-check top-down inventories

Sacramento illustration includes lots of assumptions but results imply:

Lots of uncertainty in regional inventories

Need to disaggregate sources to quality-check findings

Need better project and regional activity data

(spatial, temporal, fleet mix)


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Acknowledgments

The study team thanks the following individuals for

their assistance:

Song Bai, U.C. Davis

Mike Brady, Caltrans

Jos Luis Cceres, SACOG

Zhen Dai, California Air Resources Board/UCD

Gordon Garry, SACOG

Justin Kable, Port of Oakland/UCD

Robert OLoughlin, Federal Highway Administration

Jeff Pulverman, Caltrans Sharon Tang, Caltrans

Ru Wang, U.C. Davis


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For Q & A

Top Five NOx Emitters by Construction Equipment Type

OFFROAD2007 Caltrans Data

Rollers Graders Scrapers Excavators Generator Set Crawler Tractors Skid Steer Loaders Rubber Tire Loaders Tractors/Loaders/Backhoes

Main point: construction activity in modeldoes not characterize road construction per se

Documents

Construction TRB 2007 Final Revised