A simple multiple loop sensor configuration for vehicle detection in an undisciplined traffic

This paper presents an inductive loop vehicle detection system suitable for heterogeneous and less-lane disciplined traffic. Vehicle detection system based on conventional inductive loop principle has been in use but works well only for lane based and homogeneous traffic. A multiple loop system that is suitable for sensing vehicles in a heterogeneous and less-lane disciplined condition has been reported recently. This paper proposes a new measurement scheme for the multiple loop system. According to the new scheme, all the inductive loops are connected in series and only two cables are required, instead of two per each loop, between the measurement unit and multiple loop system, there by reduces the system complexity. Each loop has a unique resonance frequency and the excitation given to the loops connected in series is programmed to have frequency components covering all the resonance frequencies of the loops. When a vehicle goes over a loop the corresponding inductance and resonance frequency will change. The shift in frequency or its effect for individual loops can be monitored simultaneously and the vehicles can be sensed and identified as bicycle, motor-cycle, Car, Bus, etc. A prototype multiple loop system has been built and tested based on the proposed measurement scheme. The system developed sensed, classified and counted the vehicles accurately.