Lane closure plan (temporary traffic control, fictional)

Most of a lane closure is road, not work.

To take one lane for 500 ft at 45 mph, the plan needs 1,050 ft of advancewarning, a 540 ft taper and a 360 ft buffer in front of it - about half a mileof road for 500 ft of work. The plan above says that in words; the strip belowsays it in length.

The buffer is drawn empty on purpose. It is not spare room: it is thedistance a driver needs to stop. Park a truck in it and it is no longer abuffer, it is the back of the queue.

Taper length is L = W x S at 45 mph and over (offset width x speed), andL = W x S squared / 60 below that. The difference is not a rounding: at30 mph a 12 ft offset needs 180 ft, at 45 mph it needs 540 ft.

Source - MUTCD Part 6 (tapers, sign spacing, device spacing).Sign spacing letters follow MUTCD Table 6C-1: A is from the taper to the first(nearest) sign, B between the first and second, C between the second and thethird (furthest upstream).Speeds, widths and lengths are fictional; the road authority decides them.