RTD has technology that can automatically stop its light-rail trains from colliding with each other, but the transit agency doesn’t have the ability to slow a train rounding a sharp bend at high speed, The Denver Post has learned. Decisions on how to best safeguard light-rail systems in this country are largely left up to individual transit agencies, and the Regional Transportation District had no automatic checks in place to override an R-Line light-rail train that went off the tracks last month in Aurora, leaving a woman with a severed leg and a half dozen other riders injured. According to multiple witnesses, the derailment occurred as the train was going too fast around a 90-degree curve at the intersection of South Sable Boulevard and East Exposition Avenue.