Roundabouts cost more.

Modern Roundabouts are usually less expensive than traffic signals. Roundabouts do not require expensive signal equipment or maintenance of that equipment. In Anchorage, the initial construction cost of a roundabout is approximately equal to the initial construction cost of a signal. However, maintaining signals costs Anchorage taxpayers approximately $15,000 per year for each signal. Over the long run, modern roundabouts are much less expensive than traffic signals.

Modern roundabouts also move traffic much more efficiently than traffic signals. Because of this benefit, the streets between roundabouts do not have to be constructed with as many lanes as the streets between signals. Because the modern roundabout allows funds to be expended where they are needed most - at the intersections - costs can be reduced on the streets themselves. For example, the modern roundabout interchange at Dowling Road eliminated the need for an expensive, and time-consuming bridge-widening project under the New Seward Highway. At least $1,000,000 of taxpayer's money was saved.

A similar savings was delivered to the taxpayer on the Southport Drive
project. Originally, the project budget was $2,700,000. Because modern
roundabouts move traffic more smoothly than stop-controlled or signalized intersections, the number of driving lanes on Southport Drive could be reduced from two lanes in each direction to one lane in each direction. Reducing the street width between the intersections saved Anchorage taxpayers a great deal of money. The modern roundabout was a big reason why the construction budget was cut to under $1,600,000, and that included a very impressive $188,000 for landscaping.