Japan was the first country to build railway lines for high speed travel. Because Japan has many mountains, the network that already existed was made of 3'6" gauge (1067 mm) narrow gauge lines, which tended to take non-direct routes and could not be adapted to higher speeds. Because of this, Japan had a greater need for new high speed lines than countries where the existing standard gauge or broad gauge rail system could be upgraded easily. Unlike the older lines, Shinkansen lines are standard gauge, and use tunnels and viaducts to go through and over obstacles, rather than around them.