波浪车道：连续起伏的自行车练习道

Render a pump track in a sports park — a closed circuit of rollers and banked turns ridden without pedalling. Show a continuous looping ribbon of smooth asphalt about two metres wide, its surface rising and falling in a rhythmic series of rounded humps along the straights and sweeping up into steeply banked berms at each turn, the whole thing modelled as sculpted earth rather than built structure. Detail the asphalt as freshly laid and dark with a fine texture, its edges meeting mown grass in a clean line without kerbs. Show the enclosed infield planted with tough ornamental grasses, and the outer slopes turfed. Include a small flat start platform with a ramped drop-in, a signboard with rules, and a bench on a slight rise where parents watch. Show riders of different ages — a child on a balance bike on an inner beginner loop, older riders on the main circuit. Light with warm late-afternoon sun so the banking casts strong curved shadows. Photorealistic, sculptural, dark asphalt and green, elevated three-quarter view.