How to route numerous parallel grooves

[ColossusX]

I just got a new van and am redoing the racking from my old van.  I had screwed strips of plywood to the box sides for my shelves.  But for my new racking I want to route the shelf grooves.  Each box side will be 60" (approx 1500mm) tall with the grooves spaced every 2 1/2 inches (close to 64mm). I need 20 grooves approx 12" long per upright so 40 grooves per box. And anywhere from 6-8 boxes in the van.  Is there a fairly easy way to do this and get accurate results?  I have the Makita cordless palm router with guide rail attachment and a larger dewalt 618 with plunge and fixed bases. Obviously I dont use them much lol 

Thanks.

 

[rst]

Plywood guide fence attached to cleat that fits into the first groove that will place each successive groove at the desired place.  Each groove will place the next.

 

[sandy]

As a suggestion, do all of your routing on a sheet that is twice the width of the desired depth, and then cut the sheet in half, as that will insure that the dados will be perfectly aligned with one another.

Sandy