Optimizing signal timing is considered a low-cost approach to reducing congestion. Based on data from six separate studies, the costs range from $2,500 to $3,100 per signal per update. While this range is reasonable, costs could be slightly more or less.
An executive agreement is an agreement entered into between a foreign government and the executive branch of the United States. Although the agreement binds the United States with as much force as a treaty, it is not as formal as a treaty and does not require Senate approval.
Under US law, the difference in between treaty and executive agreement is whether the President has the authority to execute it without the advice and consent of the Senate. If he or she has such authority, it is an executive agreement, and if not, it is a treaty.