The page https://docs.microsoft.com/en-us/bingmaps/v8-web-control/modules/directions-module/directionsrequestoptions-object outlines a `routeDraggable` property which on setting to `false` should disable the ability for the user to drag a route. It
seems that this property is ignored and/or overwritten, as the generated route is always able to be dragged.
Codepen example here: https://codepen.io/sizzlepop/pen/bGepyBJ (requires Bing Maps API key).