BNSF Railway Co. is cutting the speed of oil-carrying trains in some urban areas to as slow as 35 miles per hour, a 30 percent reduction, to improve safety following crude-by-rail accidents this month.

BNSF, owned by Warren Buffett’s Berkshire Hathaway Inc., implemented the slower train speeds and measures to inspect tracks and rail cars more closely on March 25, Mike Trevino, a spokesman, said on Monday. The reduction trims the speed from the 40 mph (64 kilometers per hour) in high-risk areas that railroads, including BNSF, last year voluntarily installed in 46 urban areas. In some cases, the cut is from 50 mph for cities with populations of at least 100,000, the Fort Worth, Texas- based rail company said.

“This change goes beyond the high-threat urban area definition to be municipalities with populations of 100,000 or more,” Trevino said in a telephone interview.

The dangers of hauling crude oil by rail was highlighted in an accident this month in which a BNSFtrain jumped the tracks near the Mississippi River-town of Galena, Illinois, and five of the 21 cars that derailed caught fire. The BNSF accident occurred a few days before a Canadian National Railway Co. crude train was involved in a fiery crash near the Canadian town of Gogama, Ontario.

The safety steps include wider use of monitors to detect overheated wheel bearings on rail cars, with units placed every 10 miles on crude-by-rail routes along critical waterways instead of the current 40-mile spacing, Trevino said. The railroad will also inspect track more frequently on crude train routes and lower the tolerance for pulling out rail cars that register on wheel-impact detectors.

“The result will be that you will take a car out of service sooner compared with today,” Trevino said.

The actions aren’t being taken in conjunction with other railroads, although they are aware of the measures, he said.