Blank Mexican federal highway shield with the D (for Directo) insignia on it. Shields of this type are sometimes used on new federal toll highways that have not yet been numbered
<a href="//commons.wikimedia.org/wiki/User:Fredddie" title="User:Fredddie">User:Fredddie</a>
Based on <a href="//commons.wikimedia.org/wiki/File:Carretera_federal_57D.svg" title="File:Carretera federal 57D.svg">File:Carretera federal 57D.svg</a> by <a href="//commons.wikimedia.org/wiki/User:Fredddie" title="User:Fredddie">User:Fredddie</a>