Words you may see in Tokyo - Tokaido (東海道）ex. Tokaido shinkansen, Tokaido line

The Shogun enforced the, “Sankin-kotai”（参覲交代）, a policy that had the daimyo（大名） spend every alternate year in Edo（江戸）.    As a result the large number of daimyo that needed to either, come to Edo or, return to their home provinces encouraged road building, the creation of inns and other factilities along the route which ultimately resulted boosted economic activity.  

Here is a image of "Sankin-kotai". 

There were five such roads ("Go-kaido"＝五街道) and Tokaido is one of them. There were fifty-three government-sanctioned post stations, "Shukuba"（宿場） along the Tōkaido for travelers to rest in. These stations consisted of porter stations and horse stables, as well as lodging, food and other places a traveler may visit. The original Tōkaido was made up of 53 stations between the termination points of Edo and Kyoto. 

If you take a train (or Shinkansen) from Tokyo to Osaka/Kyoto, you will likely to take "Tokaido shinkansen". Since the route is similar to Tokaido in Edo period, this name is used for this train route.