I've managed to trap 3 this year, mainly by being patient, and setting them up. Got 2 with the old style Victor traps, and one in a live trap. Trick is to leave the Victor traps un set but baited (I used old cat food) until the rats eat the bait. Then set the trap and bang! Use rubber gloves...
Terriers are amazing, and mine get 3 or 4 a year. Problem is, rats are fast, and they know the territory, and their first instinct is to dodge under someplace the dogs can't go. What the dogs do is keep the gene pool clean.