sentences:  Three-level stacked roundabouts are quite common in Britain because they use less land than other four-way junctions where both roads are grade separated.However, they have lower capacity for turning movements – some have had direct-linking slip roads added later in an attempt to solve this problem.Examples of such junctions are found at Lofthouse, West Yorkshire (M1/M62) and Swanley, Kent (M20/M25) .