The DeKalb County School System has taken delivery of three new buses for the 2013-14 school year.The new Blue Birds have Cummins 6.3 turbo diesel engines with systems that reduce emissions and boost mileage.Transportation Director Jimmy Sprague told the Review that he is pleased with the advances in safety, emissions and fuel mileage in the new units, particularly the new emissions measures and safety features.“There have been a lot of improvements in the last few years in buses,” Sprague said.“The service door on these buses is 2.5 inches taller and 2.5 inches wider than older buses, and the driver’s compartment is more ergonomically designed and roomier. The Blue Bird also has the tightest turning radius of any school bus on the market.”The new buses also feature diesel emissions fluid (DEF) injection.DEF is an additive that reduces emissions and increases mileage.“It reduces emissions to zero percent,” Sprague said. “You won’t see any black smoke out of these buses, and it makes them much quieter, too.”