The GE Dash 8-40BW, or B40-8W, is a four-axle diesel locomotive built by GE Transportation for the Atchison, Topeka and Santa Fe Railway (ATSF) between 1990 and 1992. It is part of the GE Dash 8 Series of freight locomotives.
The locomotive model designation is interpreted as follows: B (B type truck arrangement, 2 axles per truck) 40 (4000 horsepower) -8 (the generation when it was designed, in this case meaning the late 1980s) W (Widecab).
ATSF was the only railroad to order the B40-8W, and a B unit (cabless booster unit) was almost made with it, but because the price would have been the same for B40-8Ws with cabs or without, they decided to order units with cabs only.
All of ATSF's B40-8Ws were passed on to BNSF Railway, with some later sold to other railroads.
While originally built for high-speed intermodal service, by the mid-2000s the B40-8Ws had been bumped to local service.
In mid-2010, BNSF put 15 B40-8Ws up for sale. These units were on long-term lease and were returned to their lessor. As of 2016, three units are operated by the Providence and Worcester Railroad in New England. The rest of BNSF's B40-8W fleet is, as of 2019, undergoing rebuild and refreshment at GE as preparation for their new role as local freight units.