Many expressways in Tokyo were made over the rivers just before Tokyo Olympic in 1964, without any elaborate plans. And many rivers and canals were filled in to make them. A river used to flow under this expressway.
Many canals covered the whole of Edo, the old name of Tokyo, like a web and boats were major transportation. But now most of them disappeared and autotrucks took place of boats.
Now many roads flow like blood vessel in Tokyo and they are usually in arteriosclerosis. Because Tokyo is located in the middle of Honsyu, extending north and south, and you need to pass through Tokyo to go to the northern part to the southern one.
Haphazard bypass surgery makes expressways in Tokyo "slow" ways.