One of the "luckier" restored main line locomotives is Santa Fe 3751, which has done some excursions on the (Southern Calif.) Metrolink San Bernardino Line, and a combination of the Metrolink Orange County Line and the San Diego Northern. Since both of these routes have their heaviest traffic on weekdays (mostly suburban passenger service), and, except for LA to Fullerton, relatively light freight business, they provide a place for the Northern to run non-stop for dozens of miles, on well-maintained track. One of the ironies of the San Bernardino Line is that two segments of the route follow a Pacific Electric interurban line that only saw steam during World War II.