This paper addresses the problem of designing optimal locations for roadside servers used to collect real time travel information for Advanced Traveler Information Systems (ATIS). The objective is to maximize the information captured with regard to the network traffic conditions under certain constraints, such as budget limits. The paper formulates the problem as a two stage problem. In the first stage, it uses the technique of sensitivity analysis to identify a subset of arcs as "critical", in the sense that the flows on those arcs contain the most critical information reflecting changes in the travel demand. Following that, the paper formulates the second stage problem as a maximum arc covering location problem to select more arcs out which, together with those selected in the first stage, cover the network in a best way as information collectors. Then the paper uses an example to illustrate the methodology.