Building house in b.17

Is building house in b-17 islamabad a good option?

My main concerns are:
1. The access to b.17 as its been 2 years i own a plot in b.17 and i heard at that time that margalla avn will be constructed in no time but its been 2 years already.
2. My second concern is that i have observed a decline in the market of b.17.