ABSTRACT
Knowledge of fundamental traffic flow characteristics-speed, volume and densityand associated analytical techniques are essential requirements in planning, design, and operation of transportation systems. The fundamental characteristics have been studied at microscopic and macroscopic levels. Existing traffic flow models are based on time headway, flow, time-space projectory, speed, distance headway and density. These have lead to the development of a range of analytical techniques: demandsupply analysis,capacity and level of service analysis, traffic stream modelling, shock wave analysis, queuing analysis and simulation modelling. The focus of this research has been homogenous traffic conditions-traffic which consists primarily of cars or motorized vehicles of similar characteristics. We are now faced with a situation where more than half of the world's population is living in megacities in the developing region. Large differences in income levels and social disparities have lead to the development of 'cities within cities'. Each level of the city, with its own level of technology and land-use patterns, exists in close geographical proximity with other cities of different patterns. This is reflected in the travel and traffic patterns existing in this region. The same road space gets used by cars and buses, along with locally developed vehicles for public transport such as three-wheeled scooter taxis, scooters and motorcycles, bicycles, tricycle rickshaws, animal and human drawn carts. Infrastructure which is designed on the basis of homogeneous traffic models has failed to fulfill the mobility and safety needs of this traffic. Despite low levels of car ownership, accidents and congestion continue to plague this region. This is the right time to question the applicability of models which have been developed for a very different situation.
