The National Center for Safe Routes to School does not have an image library. However, if you are interested in images of children walking and bicycling to school please visit the International Walk to School Day photo library at IWalk.org. Here you will find hundreds of images searchable by county, region, city and year.
Also, the Safe Routes to School Guide contains photos ranging from engineering and enforcement treatments to children walking to school and participating in encouragement activities.
The Pedestrian and Bicycle Information Center has an image library with thousands of photos searchable by topic.