The whole idea isn't roads and bridges, pre-schools, or infrastructure, the idea is how to create 855,000 new federal bureaucrats, on the payroll, to administer it.
That is why, Washington DC is the boom town, unlike any boom town in recent memory. Obama has already doubled the federal work force and is trying for more. Have you seen any improvement in your life or home town? Have any of those employees (I refuse to call them workers, that implys work) started at minimum wage?