In 1923, the city of Detroit and the railroad began a plan to build 22 grade separations; both parties agreed to share the cost.

This grade separation was agreed in 1890 after much litigation.

Traffic engineers usually refer to the latter as a grade separation.

The city also encouraged the railroads to build grade separation throughout the city.

Usually it is separated from other traffic by a concept called grade separation.

The bridge carries both road and rail traffic, without grade separation.

In September 2008 a contract was awarded to provide a grade separation.

The grade separation was completed for $142m in 7 months.

As such, there was an urgent need for grade separation.

The grade separation was completed in late 1941 - just nine weeks before the United States went to war - and cost $4.3 million.