The plural form is not more correct. The two say something slightly different, and are responses to different conditions or assumptions. In this case, for me, the key variable is what is meant by 'here.' If we meant a wider area, like here (in this town), I would most certainly use the plural, because I would have expected there to be several. On the other hand, if 'here' meant a smaller area in the immediate vicinity of the speaker, say just one intersection, as I would be more inclined to interpret it without further context, I would not expect to find more than one traffic light, and would use the singular form.