This is not a walk across the bridge, its a climb over the top. Guides will tell you that a climbers have ranged in age from a 12 years old child to a 90 year old man.
You'll need to arrive at least 15 minutes early. Once you check in, you'll watch a short video on the climb. After, in the next room you'll sign some paper work and take a beathalizer test.
Then, onto the changing room where you empty your pockets, and put on your bridge climb suit. Next you meet your bridge climb guide and begin some practive runs on the bridge pieces that they've created inside the building.
After you've completed your practice runs with your group, you move on to get the rest of your gear. Depending on the weather and time of day this could include: fleece, rainjackets, head torches (lamps), gloves, and hats. Everyone gets a walkie talkie so they can communicate with the group leader.
One finished, you move outside and walk to the bridge where you follow the catwalk. At the end of the catwalk, you climb up ladders on the edge of one of the bridge pylons. Once at the top, you climb the actual top arch. Its slightly challenging, but do-able by most people. At the top, you walk across and then back down the same route on the opposite side of the bridge.
We did the night time climb. Neither of us are extremely physically fit. The view from the top, 134 meters above the ocean looking out at the city and the opera house is amazing. You are on the bridge above moving traffic, in the open air. Its an amazing experience.
You are cabled to the bridge at all times so you can not fall. Keep in mind that you can not bring anything on the bridge with you. This is a safety precaution, falling cameras can pose a major hazard to the traffic below. Your guide will bring a digital camera and take pictures of each group member at various points on the climb. You'll get one photo taken at the top for free. Other photos are about $4 US.
The climb itself is about $60 US, a little more expensive at night. Make 3 hours of time on your trip to do something you'll never forget!