It depends on how much water the stream takes at its highest flow. A readymade concrete culvert is the easiest solution, the local water authority should be able to help you work out the required dimensions for your stream. Normally you would dig out the stream so that when the water is at its lowest it flows freely, without creating a pool at the entrance, and then concrete the top of the drain to create your drive. The alternative method is to build a bridge. This will require footings at each end and bridging the sections. Talk to a structural engineer for dimensions and loads, but a simple beam and block construction should suffice.