+ url: document.location.protocol === 'https:' ?
+ 'https://{s}.tile.thunderforest.com/transport/{z}/{x}/{y}.png' :
+ 'http://{s}.tile.thunderforest.com/transport/{z}/{x}/{y}.png',
+ attribution: '© <a href="http://www.openstreetmap.org/copyright" target="_blank">OpenStreetMap</a> contributors. Tiles courtesy of <a href="http://www.thunderforest.com/" target="_blank">Andy Allan</a>'