I heard of state tenders where they basically have some minimum requirements that have to be met and otherwise choose the cheapest option. For a large amount of vehicles it is probably cheapest to design one that meets all the minimum requirements exactly.
When Seattle started with light rail, they ordered custom cars that were "specially designed for the Pacific Northwest". Nobody was ever able to explain what was special about the PNW and light rail cars. But hey, it cost a lot of money!
There were two major differences from the stock Kinkisharyo cars, one technical, one political:
- Most North American light rail systems use 750V electrification, Sound Transit used 1500V to reduce the number of substations.[1]
- The cars arbitrarily had to be assembled at Boeing in Everett "because of a 'Buy American' requirement written into the Kinkisharyo International contract ... Federal grant money is being used to help pay for the light-rail fleet, which means a percentage of the rail cars must be built in the U.S. and that final assembly must take place in Sound Transit's service district".[2]
Seattle's cars also used 70% low-floor access for ADA accessibility and included more bike racks, which isn't unique now but were both relatively novel at the time.[3]
