“He also nominated Earl Warren and instituted the largest public works project in the country’s history. “
I assume that you are referring to the Interstate Highway System.
In 1919 Lieutenant Colonel Eisenhower participated in the first Army Transcontinental Motor Convoy.
It took them 62 days to travel the 3,251 miles from Washington DC to San Francisco.
“As an observer for the War Department, Lt. Col. Eisenhower learned first-hand of the difficulties faced in travelling great distances on roads that were impassable, and that resulted in frequent breakdowns of the military vehicles. These early experiences influenced his later decisions concerning the building of the interstate highway system during his presidential administration.”
There was no need for the executive branch to build it (its Bureau of Public Roads had its powers increased for this self-appointed task by an all-too-willing Congress). The private sector would have been more than up to the task.
The private railroads proved by helping to win WWII that Wilson was absolutely wrong to nationalize them in WWI.
And what with Eisenhower inspired by the Reichsautobahn, perhaps he forgot that those roads made things easier for the Allies to get to Berlin? Strategically problematic to introduce the same vulnerability to the home front.