Developing a theoretical model to improve the road network the a historical city in Iraq

Fig. 3
.
Balance of supply and demand
Fig. 2.
"Zoning" model as part of the Road-Street- Network
E3S Web of Conferences 
263
, 05007 (2021)
FORM-2021
https://doi.org/10.1051/e3sconf/202126305007
4

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Mobility usually takes place over fixed capacity infrastructures, which translates into the 
availability of transport. The transport system consists of two main components: the 
demand for travel and the supply of transport [21, 22]. The supply of transport is the 
capacity of transport infrastructures and modes for a given duration within a geographical 
region. Experts typically express their capabilities in terms of infrastructure (capacity),
facilities (frequency) and networks, (coverage). The need for travel is a demand and the 
need for mobility. It can be expressed as the number of people, volume, or tons per unit of
time and space, similar to transport supplies [22]. The increasing transportation demand 
creates more and more mobility-related problems.
The mathematical model was used in this research is the coefficient of demand /supply ratio 
[19]. Vuchic States that the criteria to determine the efficiency of roads by finding the ratio 
of demand/supply. In this work unites were used are the cars/hour, people /hour, 
bicycle/hour, and bus/hour [24], the ratio should range (0, 1). 
=

(1)
Where: 

K: Coefficient of accessibility 
V: Demand, C: Supply 
Where V is the demand in the urban area of the study community, C is the supply of 
the roads. The value K is the combined value that will be within the range (0, 1). If
there are no enough roads in the area, the value will be (1) if K minimize and closer to
the number 0, refers to more connection of the road network and the more coverage
of the area, therefore is better the lower ratio of the coefficient.