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California Temporary Traffic Control Handbook <br />19 <br />Table D – Longitudinal Buffer Space or Flagger Station Spacing on Downgrades <br />Speed <br />(mph) <br />% Downgrade (Buffer Space) <br />Level Road <br />0% (ft) <br />-3% <br />(ft) <br />-6% <br />(ft) <br />-9% <br />(ft) <br />20 115 116 120 126 <br />25 155 158 165 173 <br />30 200 205 215 227 <br />35 250 257 271 287 <br />40 305 315 333 354 <br />45 360 378 400 427 <br />50 425 446 474 507 <br />55 495 520 553 593 <br />60 570 598 638 686 <br />65 645 682 728 785 <br />70 730 771 825 891 <br />Table E – Taper Length Criteria for Temporary Traffic Control Zones <br />(for 12 feet Offset Width) <br />Speed* <br />S <br /> (mph) <br />Minimum Taper Length ** <br />For Width of Offset 12 ft (W) <br />Merging <br />L <br />(ft) <br />Shifting <br />L/2 <br />(ft) <br />Shoulder <br />L/3 <br />(ft) <br />Down <br />Stream <br />(ft) *** <br />20 80 40 27 50 <br />25 125 63 42 50 <br />30 180 90 60 50 <br />35 245 123 82 50 <br />40 320 160 107 50 <br />45 540 270 180 50 <br />50 600 300 200 50 <br />55 660 330 220 50 <br />60 720 360 240 50 <br />65 780 390 260 50 <br />70 840 420 280 50 <br />* Posted Speed, off peak 85th percentile speed prior to work starting, or the <br />anticipated operating speed. <br />** For other offsets use the following merging taper length formula for L: <br />For speeds of (40 mph) or less (L=WS2/60) <br />For speeds of (45 mph) or more (L=WS) <br />*** Maximum downstream taper length is 100 feet.