The Southren Motorway Walk, Scooter Ride Run series
The cache is small so you will need to bring your own pen, I have found with experience that to rectieve the log from these caches you may need some pliers or tweezers as the log can be tricky to get out due to the amount of room and plastic bag to keep it dry.
This is a fast bit of the track so beware of cycle-muggles