The elephant trek will mainly be used for the keepers to place food along so the elephants can forage. This will give them great exercise and they don't necessarily need to be supervised.
In this particular design, the dead end makes it appear to be dangerous to give access to more than one elephant at a time. I could be off-base on this, but a narrow corridor looks like a great place to get cornered by a herdmate.
None of the elephants there have a problem with aggression. I would think they would separate Kandula from Ambika and Shanti before the exhibit gets completed.
It doesn't matter if none of their elephants currently exhibit any signs of aggression towards one another. You don't build exhibits with corners or dead ends.. so there is most likely more to this than it appears.
Also notice that the habitats are sloped as is the Trek so the animals will get a bit more exercise. The Trek bit seems to me to be longer than in the original concept plan.
Last I read they were planning to have around 8 elephants when the trails were completed. 3.5 acres isn't that bad.. though it is quite a large strech.
3.5 acres is anything but bad. The San Diego Wild Animal Park has a family of 11 elephants on 3 acres and the elephants have plenty of space if you have ever seen the exhibit.
