Abstract This paper proposes a train wheel detection system based on the use of an inductive sensor array. It allows multiple detection points and uses coded signals in order to work with low signal to noise ratios. The sensor array consists of pairs of sensor coils placed at every detection point. In this work, unlike previous work about this matter, the coils are interconnected in series as a part of a Maxwell bridge that is used to excite the coils and to receive the unbalance signal when there is a perturbation caused by the train pass over the detection point. Furthermore, the signal used is encoded with complementary sequences, allowing a single process of many detection points. Finally, the gain of the process allows placing the signal-processing module far away of the detection point, which makes it possible to work with a detector system without electronics near the railways.