アメリカでは義務です><
28 C.F.R. § 35.150(d) (2)
"If a public entity has responsibility or authority over streets, roads, or walkways, its transition plan shall include a schedule for providing curb ramps or other sloped areas where pedestrian walks cross curbs, giving priority to walkways serving entities covered by the Act, including State and local government offices and facilities, transportation, places of public accommodation, and employers, followed by walkways serving other areas."
ちなみにひとつ前の項を読むと期限もわかる><
"within six months of January 26, 1992"
1992年1月26日から6か月以内に移行計画(?)を作って公表せよってことっぽい><