Sea Cliff Bridge now weighs slightly more than it did four years ago - thanks to the growing number of padlocks that have been attached to its rails.To celebrate Valentine's Day and 34 years of marriage last month, "Del and Shell" engraved their names on a Chubb padlock and secured it to the bridge.The couple joined almost a dozen other lovers, families and groups who are marking important dates by adding a padlock to the bridge and throwing the keys into the sea below.The tradition is nothing new but the Illawarra's most famous bridge now joins the Eiffel Tower and other prominent landmarks around the world in becoming a place where people can literally express the bonds of love.In Riga, Latvia, the bridge into the Old Town is covered in padlocks - the result of a newlywed tradition. The Eiffel Tower's top viewing platform has also become a focal point for locks of love, with many engraved with statements along the lines of, "Jack proposed to Jane here and she said yes", then the date.The Mercury found nine locks attached at the bridge yesterday, with the earliest installed three years ago."John and Fay" appear to be the instigators of the trend, attaching a lock to celebrate 40 years together in June 2006.They were followed by "Jan and Ben" in November 2007 before lock fever really took hold in 2008."Peter and Brianna" notched up 20 years, the "Ryde Group" made the trek to the bridge, while only "Louise B and Tom G" know why December 9 is important.Perhaps the most interesting is the lock that says, "Happy 1st Father's Day to the best daddy", not just because the father appears to be one lucky chap, but because the padlock features a combination-lock rather than a keyhole. The locks are located on the southern and northern approaches to the bridge.