Assume you are an observer standing at a point along a three-lane roadway. All vehicles in lane 1 are travelling at 30 mi/h, all vehicles in lane 2 are travelling at 45 mi/h, and all vehicles in lane 3 are travelling at 60 mi/h. There is also a constant spacing of .5 mile between vehicles. If you collect spot speed data for all vehicles as they cross your observation point, for 30 minutes, what will be the time-mean speed and space-mean speed for this traffic stream?