The city of San Diego has big ideas for downtown streets. Their draft Downtown Mobility Plan outlines a network laden with protected bike lanes, pedestrian greenways, curb bulb-outs, road diets and more. If the plan can make it from concept to construction, it will remake the city core for biking and walking. “Just getting to this stage is transformative,” says Sam Ollinger, executive director of nonprofit advocacy group BikeSD. “If they implement the plan, it’ll…