Next week American Idol will air on Tuesday and Wednesday from 8-9:30p and on Thursday from 8-10p. On Tuesday March 1 Raising Hope will air from 9:30-10p getting the Idol boost. Traffic Light will get that boost on Wednesday March 2 at 9:30p.
While Raising Hope on Wednesday makes some sense, Traffic Light seems like a waste. That's based on prior ratings for both shows and not a commentary on show quality. Fox has a tendency to not throw in the towel sometimes (e.g. "wasting" Idol lead-in on Human Target.)
I guess they figure looking like they gave it the old college try makes more sense than airing a Family Guy rerun. They've gotta air something, but I'd go with something else. Of course such decisions are a luxury for Fox. It will come out ahead next week regardless by airing 5 hours of American Idol (and the two hours on Thursday, March 1 will be the only original programming of the night on the broadcast nets that night).