The importance of accurate prediction of travel time in transportation engineering is irrefutable. Travel time is highly used in traffic management and planning. The accuracy of travel time prediction relies on the accuracy of the travel time data. Various methods are being used in collecting travel time data. Recently, a new method in collecting travel time data is introduced that is called Bluetooth technology. In this method, a number of Bluetooth sensors are deployed over the traffic network that can detect the Bluetooth devices in the vehicles to determine the vehicles' travel time based on matching identification and time of identification of the same Bluetooth device at two consecutive sensors.

The goal of this study is to find the optimal number and location of the Bluetooth sensors in a network in order to collect travel time data with a high reliability. Two formulations are proposed for modeling this problem. The formulations consider a new collection of reliability issues. Furthermore, the proposed formulations are able to solve the problem on large networks exactly. Moreover, various case studies of real world networks are conducted for both formulations and the results are compared.