Spool Heads Quarter Mile track kit

How wide is the 4 lane? I have dual lane right now to start my track build but like the four lane, and don't know if I have enough room for 4 lanes and diorama stuff around it. Thanks. 

I have been using his two lane system for a while with the Slanman start gate and timer. The track is pretty smooth and very easy to set up. It is a bit wider and the cars move around a little more, but I still like it more than orange track. 

Lloyd