Creating a new system of radial and belt roadways to serve Pittsburgh and its suburbs was challenging, as the existing roads, laid out before the advent of the automobile, often followed serpentine routes that left planners with few options.

The department’s engineers lamented they “must go where they could among the bluffs and gorges,” noting that “a common assertion is that there is not a mile of tangent highway in Allegheny County.”

The article stated that new locations “must be searched out along side hills broken by many ravines.”

In most cases, the only possible route changes required extensive work flattening grades and curves.