Requirement for using channelizing devices (e.g. cones) to separate traffic from the work area for a work operation

Minnesota DOT requires the use of cones but is having a difficult time enforcing compliance. Because of high volumes of trucks (250 to 300 a day in many cases) contractors and their field inspectors seem to think it is too difficult to accomplish. The concern is that motorists who are allowed through some time after the pilot car and queue have gone down the road are often confused as to the closed lane. Therefore, MnDOT allows extended spacing of cones past the flaggers but still wants to see normal spacing at the flagger stations. MnDOT also limits lane closure length by special provision in contracts.