The Origin–Destination (O–D) matrix, is an important information in transportation planning and traffic control.
Rapid changes in land use, particularly in developing countries, have been and are on an increase, which makes the estimation and observation
of this matrix more significant. The objective of this paper is to observe O–D matrix under two scenarios. In the first scenario, it is
assumed that the traffic network is equipped with path-ID sensors. In this situation, the goal is to determine the optimal number and
location of these sensors in the network, where by applying collected information through these sensors, the O–D matrix is observed.
Because path-ID sensors are not available in many cities, in the second scenario the interview alternative is proposed in order to observe
O–D matrix. The interview method has encountered some restrictions. Several mathematical programming models have been developed to overcome
these restrictions. To illustrate these proposed methodologies, they are applied in the Nguyen–Dupuis transportation network and the results
are analysed. By applying the model on the intercity road network in the Province of Isfahan (Iran), a large network, the efficiency of these
proposed models is demonstrated. Finally, some conclusions and final recommendations are included.