Being the main capital city in Sri Lanka, Colombo is functioned as the hub of administration and commercial activities, thus it is a very busy and vibrant place with heavy vehicular traffic, and it has a steady traffic growth for several decades.As a tropical Island, Sri Lanka experiences a high level of ambient particulates.Average of ambient particulate matter (PM-10) level in Colombo exceeds the WHO s latest guideline of 20 micrograms per cubic meter (μg/m3), and it has an unhealthy situation in relation to the particulate pollution.Total vehicle population of the country is 5,203,678, and about 51 # of them are consisted with motor cycles.The second highest one is three-wheelers takes up about 16 # of the total.Further 10 # of motor cars and 1.8 # of buses clearly show that the neediness of a well managed transport system as the transport sector accounts for about 60 # of the total fuel consumption in Sri Lanka.Five major sectors that are related to power generation, fuel conversation, industry, domestic and transport have been identified as major causes for air pollution , and among them emission of transport sector has been calculated as 48 # of (SO2) sulphur dioxide and 47 # of (NO2) nitrogen dioxide in Sri Lanka.The most visible and frequently mentioned transport problem of the Colombo city is its traffic congestion and environmental pollution due to improper road network, poor city planning, insufficient traffic control systems and poor maintenance of roads.On the other hand poor maintenance of vehicles increases air pollution by air-borne particles from diesel vehicles and carbon monoxide and volatile organic compounds from petrol vehicles.Hence, this paper aims to discuss on driving forces / causes of such environmental problems , existing policy initiatives / measures at different level, policy / knowledge / information gap in relation to the transport sector, present situation of traffic action , difficulties in promoting environmental-friendly transportation infrastructure and overall national strategy on urban environment and transportation.Practicability of strategies used by the National Transport Commission to mitigate environmental pollution due to transportation will also be discussed for recognition of short term and long term applicability with ongoing improvement of transportation in Sri Lanka.