1. November 28, 2006 CCOS On-Road Allocation Factors Page 1 Spatial & Temporal Allocation of On-Road Emissions CCOS Technical Committee November 28, 2006 Prepared by: Tom Kear, Ph.D., P.E. Dowling Associates Debbie Niemeier, Ph.D., P.E. UC Davis

2. November 28, 2006 CCOS On-Road Allocation Factors Page 2 Presentation Overview Preview of key issues On-road proportion & Prior CCOS work Major trends identified in the literature & heavy duty modeling practice Critical assumptions Findings Phase II priority projects

3. November 28, 2006 CCOS On-Road Allocation Factors Page 3 Preview Of Key Issues The ITN used to develop the base-year (2000) inventory is not applicable to future years Heavy-duty vehicle activity, in general, is not being modeled, but is assigned to roads as a percentage of light duty vehicle activity Speed post-processing has been to shown dramatically affect emission estimates under certain conditions Current modeling techniques are not capturing the spatial distribution of weekend travel

4. November 28, 2006 CCOS On-Road Allocation Factors Page 4 On-Road Proportion Of Emissions On-Road contributes about 1/3 of the ROG inventory Diesel vehicles are not an important source of ROG

5. November 28, 2006 CCOS On-Road Allocation Factors Page 5 On-Road Proportion Of Emissions On-Road contributes about 50% of the NOx inventory Trucks account for about 3% of VMT but 30% of on-road NOx

6. November 28, 2006 CCOS On-Road Allocation Factors Page 6 Prior CCOS Work BURDEN 2002 emissions allocated to grid cells using DTIM4 Integrated Transportation Network (ITN) from individual county (loaded) travel demand model networks Temporal allocations assigned per BURDEN and available traffic counts

7. November 28, 2006 CCOS On-Road Allocation Factors Page 7 Prior CCOS Work

8. November 28, 2006 CCOS On-Road Allocation Factors Page 8 Prior CCOS Work

9. November 28, 2006 CCOS On-Road Allocation Factors Page 9 CCOS: NOx, TOG, HDV NOx

10. November 28, 2006 CCOS On-Road Allocation Factors Page 10 Critical assumptions CCOS assumes uniform growth of vehicle activity across regions Note the variation in growth forecasts, ranging from none to more than 10x (e.g., 1,000%) ITN needs to be rebuilt using loaded networks for each analysis year (interpolated trip tables) prior to DTIM runs

11. November 28, 2006 CCOS On-Road Allocation Factors Page 11 Prominent Trends in Literature Light/heavy vehicle ratio differ by day of week Less truck activity on weekends, but the ratio of LDV/HDT increases Ratios vary by geographic location Weekdays (Mon-Thurs) have similar temporal allocation Saturday and Sunday are often very different from each other

12. November 28, 2006 CCOS On-Road Allocation Factors Page 12 Prominent Trends in Literature Speed post processing has a significant effect on congested emissions

13. November 28, 2006 CCOS On-Road Allocation Factors Page 13 Prominent Trends in Literature Statewide HVMT accounts for only about 1% of the annual total. The low HVMT suggests that changes in harvest hauling traffic patterns will not dramatically affect emissions for a typical day. Current activity factor for nonagricultural unpaved roads underestimated vehicle activity for Forest and Woodland and Urban Residential areas, but overestimated vehicle activity in Grasslands, Sand dunes and Scrubland and Urban Interface areas. Table 10. Annual unpaved road VMT in California Harvest VMT Nonharvest VMTTotal Statewide VMT 4,945,329468,023,838472,969,167

14. November 28, 2006 CCOS On-Road Allocation Factors Page 14 Heavy Duty Vehicles Not modeled but captured during calibration by increasing non- home-based-trips to match counts True freight models aggregate trip tables from inter county commodity flow data and regional gravity models. Trucks not well captured by SJV phase II truck model, or any of the 8 RTPA models. 2025 SJV Phase III truck model forecast is being extrapolated from 1978 commodity flow surveys

15. November 28, 2006 CCOS On-Road Allocation Factors Page 15 Heavy Duty Vehicles SJV Goods Movement Study Phase II (2004)

16. November 28, 2006 CCOS On-Road Allocation Factors Page 16 Critical assumptions The current approach assumes weekend and weekday trip distribution is identical, only the number of trips generated changes –Just matching base year creates a forecasting problem because behavioral component is lacking Heavy duty vehicle activity is assumed to be distributed similarly to the light duty vehicle activity on all RTPA networks. Assumes that trip based emission factors are applicable to links Existing and future activity is assumed to follow the same spatial / temporal distributions

17. November 28, 2006 CCOS On-Road Allocation Factors Page 17 Findings from Phase 1 Areas of uncertainty –Spatial changes between weekday-weekend activity –Where are the trucks? –Spatial mismatch between activity data & emissions rates –Impact of better transportation data (refinement of spatial network, speed post processing, and the treatment of trip ends) –Impact of seasonality on agricultural goods movement

18. November 28, 2006 CCOS On-Road Allocation Factors Page 18 Findings from Phase 1 Best way to group daily hours of travel? Importance of speed post processing Trucks are not well represented Weekend activity is not well represented

19. November 28, 2006 CCOS On-Road Allocation Factors Page 19 Phase II priority projects TaskDescriptionCost 1.2010-2020 forecasts Statewide Model, DTIM, spline smoothing. $80 K 2.Improve truck data Model truck activity on highways and arterials, integrate w/ task (1) $75 K ($115 K if counts needed) 3.Speed post- processing Identify best method and implement $45 K 4.Improve weekend data (LDV) Create weekend trip tables, validate/calibrate relative distributions $75 K 5.Link-level EFs Trucks from Lit or E55/E98 data, MOBILE6 for LDVs $ 50 - $75 K High Moderate Low Note: cost assumptions in speaking notes window Very High

20. November 28, 2006 CCOS On-Road Allocation Factors Page 20 Phase II priority projects 1)2010, 2015, 2020 on-road forecasts. –BURDEN 2007 control totals –Statewide model (rather than ITN) w/DTIM for spatial allocation –Interpolate trip tables for intermediate year assignments. –“Disperse” (via spline interpolation) the on-road allocation to approximate the impact of network elements not explicitly modeled in the Statewide network

21. November 28, 2006 CCOS On-Road Allocation Factors Page 21 Impact of Spline Function Source: Atm. Env. V.38, issue 2, 305-319 (2004)

22. November 28, 2006 CCOS On-Road Allocation Factors Page 22 Phase II priority projects 2)Improve truck activity estimates: –Reverse fit an OD table to observed truck counts, use SJV Phase II goods movement model as an initial condition –Base projections on TAZ employment growth Rational: Heavy-duty truck activity is poorly understood.

23. November 28, 2006 CCOS On-Road Allocation Factors Page 23 Count Locations from Phase II truck Model

24. November 28, 2006 CCOS On-Road Allocation Factors Page 24 Phase II priority projects 3)Speed post processing link data –Post process speed data to represent hourly conditions –Research into the sensitivity / appropriateness of different formulations –SAS code to implement –Impacts highly congested links Rational: As shown in the literature review, the impact of speed post processing on estimated emissions can be dramatic for links operating near and over capacity conditions.

25. November 28, 2006 CCOS On-Road Allocation Factors Page 25 Phase II priority projects 4) Improve weekend spatial allocation –Incorporating behavioral characteristics into the method (e.g., ratio OD tables by trip type and ITE data). – Reverse fit OD tables to observed light duty counts Rational: Trip making patterns change along with trip generation rates for weekend activity. Currently only trip rates are taken into account

26. November 28, 2006 CCOS On-Road Allocation Factors Page 26 Phase II priority projects 5)Link level emission rates –Use emission rates and activity data with similar spatial specificity –HDV emission rates from models in the literature –Option: use E55/E59 data to construct new rates based on Kear & Niemeier 2006 –Use light duty rates from MOBILE6 –BURDEN 2007 still sets control totals Rational: Link-based emissions rates are based on road segment level activity. BURDEN trip based rates include operation over all facility types

27. November 28, 2006 CCOS On-Road Allocation Factors Page 27 Q & A What effect will time and resource constraints have on CCOS priorities? How does the on-road inventory uncertainty compare to that in the rest of the inventory? Different projects have different uncertainties and commensurate impacts Extrapolations from an inappropriate set of year 2000 assumptions would have little value. Internal consistency and a scientific/behavioral bases for on- road activity is critical.