Appendix 8A

MassDEP 2011 Mobile Source Emissions Projections - Methodology and
Calculation

 

The methodology for developing the 2009 projected emissions is discussed
in Section 9, Transportation Conformity.  As noted, the Massachusetts
Executive Office of Transportation and Public Works, Office of
Transportation and Planning (EOT), used a recently updated version of
the Massachusetts Statewide Travel Demand Model (TDM) to estimate daily
vehicle miles traveled (DVMT) and vehicle speeds.  Estimated emissions
for 2009 are based on TDM runs performed by EOT using Mobile 6.2
emissions factors provided by MassDEP  

Due to EOT staff resource constraints, the 2011 contingency projections
are not based on an updated TDM run. Rather, MassDEP used data from an
earlier TDM to project 2011 emissions. MassDEP took 2009 data generated
from the prior version of the TDM  and compared this data to the results
of the updated TDM.  It used the differences in the two-modeled outcomes
to create a ratio to adjust 2011 projections as shown below.     

MassDEP Calculation of 2011 On-Road Mobile Projections  

	 2009 Conformity Budget using latest TDM	DEP 2009 estimates using prior
version of TDM 	DIFF	% DIFF	DEP 2011 Emissions estimates using prior TDM
DEP Adjusted 2011 estimates

 EMA DVMT (000s)	         135,657 	          138,007 	-2350	-1.7%



WMA DVMT (000s)	           24,838 	            26,293 	-1455	-5.5%



STATE DVMT (000s)	         160,495 	          164,300 	-3805	-2.3%



EMA VOC*  	63.50	61.90	-1.60	-2.6%	51.22	52.54

EMA NOX*  

188.70	13.74	7.3%	142.46	132.09

WMA VOC	10.73	11.90	1.17	9.8%	9.82	8.85

WMA NOX	27.73	35.40	7.67	21.7%	26.72	20.93

STATE VOC	74.23	73.80	-0.43	-0.6%	61.04	61.40

STATE NOX	202.69	224.10	21.41	9.6%	169.18	153.02









ks/inv2002-sip-rfp nov/29-2007/ mhd-dep-vmt-diff2





*VOC and NOx are in tons per summer day. 

