An efficient transport system is not only a pre-requisite for economic development but is also important to achieve the objective of economic integration in the world economy. Insufficient transport infrastructure results in congestion, delay delivery time, fuel waste, pollution and accident1 which built inefficiencies in the economy and costs the economy 4 to 6 percent of GDP each year [Shah (2006)and World Bank (2007)], which can be saved by investing in transport services. Realising its importance, the government of Pakistan has initiated National Trade Corridor Improvement Programme (NTCIP) in 2005 to improve logistic and transport infrastructure so that it can fulfill the demand of economy more efficiently. This five years programme includes all sectors that improve performance of corridor-high way namely, road transport, railways, airports, and ships etc. The objective of the programme is to reduce the cost of doing business and improve quality of services. The study quantifies the efficiency of transport sector by evaluating the impact of public investment to improve transport services on the economy in general and on cost of land transportation in particular; i.e., cost of freight and passenger movement and cost of externalities such as congestion, air pollution and accident. The outcome of the study depends on how improved facility is achieved, i.e., who bears the cost and who benefits etc. This paper assumes tax financed public investment that not only change domestic price and demand, but also welfare and poverty. The issue is analysed in computable general equilibrium framework taking into account inter linkages of transport sector with rest of the economy. First, a social accounting matrix (SAM) is developed with a detailed transport module. Then, a dynamic CGE model is developed around this SAM and simulations are conducted for short run and long run analysis of public investment in trans port sector.