It's not a noise abatement requirement but rather, as mentioned earlier, a collision avoidance requirement. It's in place to get the Anchorage Int'l Rwy 32 departures above the Lake Hood (adjacent to Int'l) and Merrill Field (downtown Anchorage) traffic. The procedure still will not provide separation from Elmendorf Rwy 05 arrivals hence the occasional "Taxi into position and hold awaiting Elmendorf traffic" clearance. If anyone cares further, it's all spelled out in FAR Part 93, Special Air Traffic Rules.
The terrain requirement comes into play little further away from the airport for Rwy 32. That's where the procedure for no faster than best angle to 13,500' westbound (Alaska Range) and 15,500' eastbound (Wrangell Mountains) applies. Terrain avoidance for Rwy 06L&R are a different story. (i.e. Don't forget to turn)
[This message has been edited by Alaskan (edited 12 February 2001).]