Abstract:
Optimization of traffic and accurate assessment of traffic volume
on different roads are very important in transportation planning.
Optimization of traffic provides the advantage of best utilization
of an existing facility. A balanced transport system, which ensures
minimum user cost on every route, also depends on traffic
optimizatio~. The design of road layouts and pavements and analysis
of alternative highway projects are based on an assessment of
traffic volumes in a balanced condition.
This study attempts to make an independent approach in the field of
traffic assignment. It computerizes a traffic assignment model and
tends to combine mathematical analysis with subjective judgement in
order to develop a method that is reliable and easy to use in road
transport planning. The term 'subjective judgement' implies a
choice in flow - travel time relationship and modelling of delays
at road intersection. A procedure has also been developed to
assess the impact of any new road link on traffic flow over an
existing road network. Major features of the model include a
computerized procedure for finding quickest route between any trip
origin and trip destination in a road network, implementing an
iterative procedure for the assignment of traffic and developing a
method for the assessment of impact. The model was developed by
remodelling Ford-Fulkerson' s analytical algorithm of quickest route
finding for computerization and capacity restraint traffic
assignment algorithm. The impact was measured in terms of travel
impedance viz. travel time and passenger car unit- minute . The model is based on data of network structure and origin- destination
(00) matrix. It can be used to estimate the traffic volume on any
road link should a change occur in the network structure or in the
origin- destination (00) matrix.
Statistical analyses showed that the result obtained from the model
developed in this study agree very well with the practical
situations. The model was applied for traffic analysis of the road
network in metropolitan .Dhaka. In particular, the effect of
'Pantha-path' extension, a new road under construction connecting
Green road with Mirpur road, was studied. It was found that this
new road will provide nearly nineteen percent reduction in overall
travel time required by all the vehicles to travel within the study
area at peak hour. Individually, the link travel-time reductions
varied between 15 and 196 percent. A step wise procedure to obtain
the future traffic volumes on different road links by using this
model is presented to assist the user in the model's application.
