Cohoes Bridge Construction: Why Every Weekend?

I live on the Cohoes side of the Cohoes Waterford Bridge and I understand that it needs to be replaced. I don't understand, however, why they have to shut down the entire area for every weekend in July. I thought that construction was typically done overnights and evenings during the week. Again I realize that it is imperative that the bridge be replaced and that it is a huge undertaking, but why for complete weekends?

As it stands, the bridge closes on Friday nights at 8 and doesn't reopen until 6am Monday morning for every weekend in July. It is a major thoroughfare not just for residents, but many businesses on either side of the bridge rely on those who travel from the surrounding cities.

Don't get me wrong, I know it has to be done, I just think there might have been a better way to get it completed without affecting small businesses and residents alike. I guess for me, it's not that big of a deal,  I just hope it doesn't affect those small businesses too much so they can continue to stay open and thriving.