Samenvatting
The inadequacies of maintenance of traffic signals in Ire-land are described previously. Niaintenance is mostly car-ried out by the signal companies on behalf of the LocalAuthorities who have difficulty in checking the work. Asimple item of test equipment Galled a Side Tone Unit isdescribed here. It might be of assistante to personnel whoare responsible for installation and maintenance of .thesedevices.