1. A method for detecting a vehicle located in a detection zone of a roadway having at least one lane, said detection zone on said roadway at least partly covering a width of said lane, the method comprising: providing an optical detection multi-channel scannerless full-waveform lidar system operating in pulsed Time-Of-Flight operation, an optical window of said full-waveform lidar system being oriented towards a surface of said roadway in order for said full-waveform lidar system to cover said detection zone; providing at least one initialization parameter for said full-waveform lidar system; using said full-waveform lidar system, emitting pulses at an emission frequency; receiving reflections of said pulses from said detection zone; and acquiring and digitalizing a series of individual complete traces at each optical detection channel of said multi-channel system; identifying at least one detection in at least one of said individual complete traces; obtaining a height of said detection and an intensity for said detection using said individual complete trace; determining a nature of said detection to be one of an environmental particle detection, a candidate object detection and a roadway surface detection using at least one of said individual complete traces, said height of said detection, said intensity and said at least one initialization parameter; if said nature of said detection is said candidate object detection, detecting a presence of a vehicle in said detection zone; the method further comprising obtaining a distance of said detection from said full-waveform lidar system using said individual complete trace and said initialization parameter, wherein said determining said nature includes using at least one of said individual complete traces, said height of said detection, said intensity, said distance of said detection from said full-waveform lidar system, and said at least one initialization parameter; wherein said determining said nature includes: determining a probability that said nature of said detection is said environment particle if said tracking said evolution determines that said height decreases by more than a height threshold and said distance increases by more than a distance threshold; if said probability is higher than a probability threshold, determining said nature to be said environmental particle.