 In the US, Amtrak, the Massachusetts Bay Transportation Authority, southeastern Pennsylvania's SEPTA, Chicago's commuter rail service Metra, and MARC, which serves Baltimore and Washington, D.C., have all reported delays due to slippery rail.Methods for dealing with slippery rail have included trimming trees, the release of sand on the train wheels for traction, high-pressure water blasting and, most expensively, the use of high-powered laser blasts to clear the rails of leaves.Metro-North has designed a system dubbed "Waterworld", which is a large flat rail car that blasts the rails with high-pressure water jets as the car moves over it.