These are not assets you will find in your Surveyor tabs. You can use the Manage Content button or Content Manager to download the Routes. Then Merge the Route into your route or just start editing the Route you downloaded, depending on your purpose. Make a Backup of your Route FIRST!!!, be warned that several things can go wrong with merging Routes, it may take a few attempts before you get it right.
Here it is in pictures step by step;
Select a Route to download
Open a Route you have created in Surveyor
Merge the Route you downloaded to your Route
Also these CJD Routes are not currently available, but will be soon at cdesystems.com/trainz