DART, the Des Moines Area Regional Transit Authority, added 27 new buses, upgrading 25 percent of its fleet. The new buses replaced some models that were as much as 15 years old. The average bus is now just over 6 years old on average, down from 9. The new buses have a skylight in the back, wider aisles that accommodate scooters, and new wheelchair restraints. Tour the new buses via video