The technique of plastic scintillator bars coupled to wavelength shifting fibers is proposed for neutrino tracking calorimeters, in the context of very large, massive detectors for experiments on the neutrino factory beam. A prototype has been built with 180 scintillator bars interleaved with an equal number of iron bars. The light from the fibers is collected by multi-anode PMTs and converted with Amplitude–Time–Pattern self-triggering digitizing electronics. The prototype has been tested with electron and pion beams at CERN.