Environmental impact and travel time savings of a new monorail system in colombo's commuting traffic

- Evaluates the impact of introducing a monorail to the greater Colombo metropolitan area.
- Describes the actual traffic flow along one major intra-urban corridor using a monocentric city model.
- Finds that proposed monorail system reduces CO2 from commuting traffic by 42%.
- Travel time savings is the major source of benefit that justifies 26.8 km length of the monorail.

This study estimates the environmental impact and the value of travel time savings for commuters who travel to Colombo city in traffic congestion when the proposed monorail system is in place. The model considers an introduction of a monorail into a mono-centric city with symmetrically distributed radial highways converging toward the central business district (CBD), with an inelastic commuter demand. We compare the CO2 emission amount as well as aggregate travel time savings from different monorail scenarios, with the introduction of a toll as a necessary condition to generate an efficient outcome. The results show that for a monorail running at an average speed of 40 km/h a length of 26.8 km from the CBD will optimize investment and contribute travel time savings of 105 million Rs. per day or 189 million USD per year to the Sri Lankan economy, resulting in the CO2 emission reduction by 42%. A sensitivity analysis is conducted to evaluate the effects of monorail speed, commuter income, and population growth.