Speed Trap on 12

After living in Volo for almost 9 months, I continue to ask myself why the speed limit drops to 45 mph just prior to and just after the intersection of 12 and 120 and then increases back to 55 mph again. At first I thought it may have been because of a high accident rate but when I studied the boundary lines, I realized that the stretch of 12 starts in Volo, then becomes Lakemoor right when the speed limit drops, and then returns to Volo when the speed limit increases. A matter of safety or a matter of extra revenue generated by Lakemoor for speeding tickets issued to unsuspecting individuals who don't slow down fast enough??