The two mile long strech of MO 340, aka Clarkson Road, from Kehrs Mill Road in Chesterfield on the north side of Clarkson Valley to Clayton Road in Ellisville on the south side of Clarkson Valley. Clarkson Road is four lanes plus generous shoulders and a two-way left turn lane. It’s posted at 45 mph in Chesterfeild and 40 mph in Clarkson Valley. Clarkson Valley residents are concerned about traffic noise, and low speeds reduce noise. And as the surrounding area becomes more developed, there is a desire to divert north-south traffic out of Clarkson Valley and into neighboring towns. Enforcement is typically by in-car radar from moving cars or cars parked on the shoulder or up sidestreet, from behind luscious trees. Cars a typically white Ford Crown Victorias or new Chevrolet Impalas with no lights on the roof. At least one car is marked as Ballwin City police. (Ballwin is a nearby city, they might share police equipment and staff). Morning rush hour 7-10 am they run speed traps at least
two days per week, and at other random times of day until at least 9pm.