World War II Bridge?

Anthony has been doing research for the online circular ramblers' trail the Bird Henge Trail that will be created when we have built our Bird Henge near Stonehenge. Since he was a toddler, he has toddled across this bridge nearby. Researching for the trail he was curious about its origin. It has a bit of what looks like a rail set in the concrete. Railways were built in World War 1 to service local army camps but he was  told that this was a practice bridge in World War II in preparing for the invasion of Normandy.