In most instances, urban planning and design should replace traffic lights with roundabouts. 

Just operation and maintenance savings would be $8,000 per year each.  The 2012 National Traffic Signal Report Card, from the National Transportation Coalition, estimated there were 311,000 traffic signals in the United States 2012. Which saves about $7 per person per year. Add to this figure the cost of obstructing traffic flow and the costs explode.

First, there is wear and tear, and fuel consumption, for the vehicle itself.  Let’s say a typical car travels 12,000 miles per year, half of which are city miles where it stops 5 times per mile.  This makes for 30,000 stops per year.  At 1 cent per stop, the cost is $300 per year in fuel, brake pads, etc. or about $200 per passenger. Since most cars run on gas, this translates into $200 per passenger of pollution and resource depletion. 

Second, there are the time savings for the annual estimate of 30,000 stops per year.  At 10 seconds of delay per stop, with an average occupancy of 1.5 passengers per car, and an hourly rate of $15, the time component comes to… $1,875!  

Third, is the safety component.  Roundabouts are safer since cars slow down as they approach intersections. Also, left turns, the most dangerous incident, are eliminated. If just one of the accidents in the 1,000 traffic lights examined by the study resulted in a fatality, the savings start in the millions and go to infinity for the victims.  

At over $2,000 per passenger per year, the potential savings (and increase to living standards) is enormous.  

The place for traffic lights in a city designed for even flow traffic is at the busy pedestrian hubs of the main street.  In fact, downtown main streets should have additional lights for mid-block pedestrian crosswalks.  These traffic lights calm traffic in a shared street format that works primarily for commerce where shoppers, both pedestrian and vehicular, travel at safe speeds that increase both social and commercial interaction that can help to revitalize main streets.  

A recent study based on the City of Detroit confirmed this economic impact evaluation An Estimate of Potential Savings From Removing Traffic Signals in a Depopulating Urban Area by Michael H. Schrader, and Joseph E. Hummer. Wayne State University, Detroit, MI, USA. “A common rule of thumb for signalization in a city is one traffic signal for every 1,000 residents.  When a city is depopulating, does this ratio apply when determining how many signals can be removed?  The City of Detroit has lost 61% of its population since its peak.  If signals were installed to serve the peak population, applying this rule of thumb, 61% of the signal inventory should be able to be removed.”