While some neighbors may be happier, obviously people who purchased on your street are not and I feel that you can honestly say that one of the reasons you did not buy on one of the primary roads was specifically to avoid the traffic and that the buyers on those main thoroughfares knew or should have know that there was going to be more traffic on those streets.
Perhaps there's a solution that would block the one street without effectively blocking the other two main through streets?
It may be that you and your neighbors will need to meet with your Alderperson and try to work out something that leaves no one 100% happy but that left everyone reasonably satisfied.
I understand your frustration. Were you notified of the intent to consider the closure before it occurred?
I would certainly at minimum request they slow down the traffic and monitor it closely.
Recently with a DOT project taking a portion of a customers lot for the installation of a new road in the country was able to show a $40,000 reduction in value due to a side road being put in. Not sure I can accomplish the same thing based on an increase of traffic.
The issue is many people will not consider a home that is exposed to high traffic noise. So with few potential buyers it can have a negative effect.
But then so do swimming pools for many, or two story homes for others.
The key is pricing in the market based on a quality market analysis.
I would be happy to provide if needed.