From the beginning, railways and roadways shared common ground as city fathers wanted the tracks in the heart of established business and industrial areas. But as traffic increased so did problems, and by the early 20th century, overpasses were common. Fancier styles of poured concrete were found in residential areas, while functional steel types served industrial districts. In cities that wanted to eliminate grade crossings entirely, tracks were often rebuilt on elevated right-of-ways, supported by long stretches of concrete retaining walls. Railroad stations that had formerly been at street level were also rebuilt above, with stairways leading to and from the sidewalks below too. Typical of designs that have served for decades and are still common today, this series makes it easy to model these essential urban details!