Rotary interchanges operate with traffic circles rather than roundabouts. Roundabouts, junctions and bridges often become gridlocked at rush hour. Naypyidaw has four-lane roads and multilevel, flower-covered roundabouts (traffic circles). Their construction can consist of multiple interchange designs such as loop ramps, flyovers and roundabouts. Their construction can consist of multiple interchange designs such as loop ramps, flyovers, and roundabouts. The bypass is a dual carriageway with two roundabouts and two sets of traffic lights. It may have at-grade, at-level crossings with railways, roundabouts and traffic lights. Instead, roundabouts speed arterial traffic flow. Large areas are needed for tram roundabouts that include a junction between tram lines. The very centre of the centre contains a number of wide boulevards linking roundabouts. Concerns included the threat of U.S. Forest Service road closures and traffic roundabouts. This intersection is usually referred to by locals as "Five Ways" or "The Mooroolbark Roundabouts". The more familiar rules of the road for roundabouts were not adopted until the 1920s. Delays on major approaches increased as vehicles slowed to enter the roundabouts. In Sheffield, England the Sheffield Supertram systems crosses two major roundabouts.