Link travel time inference using entry/exit information of trips on a network

•This paper studies link travel time estimation using network trip data.•First method considers that trip time has a closed-form distribution as the summation of link travel times.•Properties of mean estimates, uniqueness of solutions, and confidence interval are investigated.•Two cases are discussed: one with known routes of all trips and the other with unknown routes of some trips.•Second method is a trip time splitting approximation to deal with more general link travel time distributions.