A barrier fence (218) for horse racing courses and the like having a rail assembly (219), uprights (220) and ground anchors (210) for the uprights lower ends. Fence (218) can resilient deflect under side loads applied to the rail assembly, but in the event of an excessive value of such load, or of an impact load applied directly to an upright, that upright can break away from its ground anchor at its lower end. Multiple breakaway mechanisms can be provided. Upper ends of the uprights are secured to the rail assembly and in the event of an upright breaking away at its lower end it can rotate about a horizontal axis.