Methodological or Source Data Changes to the TSI,
Year of Implementation,Change
2007,"Seasonal Adjustment models:
(i.e., models specified in
http://www.bts.gov/programs/economics_and_finance/transportation_services_index/methodology/)
Rail Freight – Intermodal: added Trading Days
Waterborne: added Labor Day effects
Transit: added Trading Days.
Aviation – Passenger: added Trading Days."
2007,Formula for conversion of BEA value-added annual values to monthly values.
2007,"Change BLS PPI for natural gas 
from  PCU221210221210P 
to  PCU22121022121012"
"2006, March release of January 2006 data.",Advancement by one month of most recent index data published with each release.
2005,Changed base year to 2000 from 1996.