Geoscience Reference
In-Depth Information
GTAP: water transport (WTP), air transport (ATP) and other transport (OTP).
Surface modes of transportation such as road, rail, pipelines and auxiliary transport
activities are all combined in the sector OTP. For this analysis it becomes necessary
to separate them.
Since 2007 is the latest reference year for the input-output tables and macro-
economic data in GTAP 8 (Narayanan et al.
2012
), we use the BEA 2007 annual I-O
table after redefinition as the complement information to further disaggregate the
combined surface transportation sectors. Truck, rail, transit and other ground
transportation, pipeline and warehousing and storage and others are separated out
of the OTP based on their industrial shares in both make and use tables. The rest of
OTP which includes auxiliary transport activities and travel agencies are combined
with the service sector. Ultimately, six modal specific transportation sectors and
seven non-transportation sectors are established.
Another challenge for the study was to add public transportation capital accounts
in the US national SAM. Public transportation capital stock has important
relationships to public transportation investment. The variation of public transport-
ation capital is primarily influenced by level of investment,
1
thus a shock of public
transportation capital in the CGE drives the social and economic variations that
result from the level of transportation investment by mode.
Another important note is that public transportation investment in the US is
highly modal biased. Highway and streets receive the most public investment while
airport, transit and water transportation receives relatively less public investment.
The pipeline and rail sectors in the US are primarily privately owned. So these
massive infrastructure investments rely on the private sector. Public investment in
pipeline and freight rail sectors is primarily used for safety and regulation related
purposes and the amount is negligible compared to other modes of investment.
Given this background, it is understandable that public transportation capital
accounts can be added only for the road, air, transit and water related sectors.
In our CGE model, the four transportation sectors are considered differently to
other sectors. The factor endowments consumed by truck, air, transit and water
include not only labor and private capital, but also public capital. The ratios of public
capital for road, air, transit and water are calculated based on the information of the
national fixed assets from BEA.
2
Since the original capital account in GTAP 8 Data
Base includes the entire capital stock (both public and private) of the economy,
values of public capital for road, air, transit and water can be calculated using the
public capital ratio times the total capital stock for each specific transportation sector.
To separate the public capital accounts from the original capital accounts for the
four transportation sectors, two assumptions need to be made. The first is that
1
Public capital stock is normally estimated through the Perpetual Inventory Method based on the
level of depreciation rate and level of investment. The linkage can be written as
K
t
¼
(1
ʴ
)
K
t
1
+
I
t
. Given the predetermined ratio of depreciation rate
ʴ
, capital stock is naturally primarily
influenced by the investment level.
2
Because there is no specific information on public transportation capital by mode except the
highway and streets, the public capital shares for air, transit and water transportation have to be
estimated based on their activity share.
