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California Temporary Traffic Control Handbook <br />Table D — Longitudinal Buffer Space or Flapper Station Spacinq on Downqrades <br />Speed <br />(mph) <br />% Downgrade (Buffer Space) <br />Level Road <br />0% (ft) <br />-3% -6% -9% <br />(ft) (ft) (ft) <br />20 <br />115 <br />116 120 126 <br />25 <br />1 155 <br />158 165 173 <br />30 <br />200 <br />205 215 227 <br />35 <br />250 <br />257 271 287 <br />40 <br />305 <br />315 333 354 <br />45 <br />360 <br />378 400 427 <br />50 <br />425 <br />446 474 507 <br />55 <br />495 <br />520 553 593 <br />60570 <br />540 <br />598 638 686 <br />65 <br />645 <br />682 728 785 <br />70 <br />730 <br />771 825 891 <br />Table E — Taper Length Criteria for Temporary Traffic Control Zones <br />for 12 feet Offset Width <br />Speed* <br />Minimum Taper Length ** <br />For Width of Offset 12 ft W <br />S <br />(mph) <br />Merging <br />L <br />ft <br />Shifting Shoulder <br />L/2 L/3 <br />ft ft <br />Down <br />Stream <br />ft *** <br />20 <br />80 <br />40 27 <br />50 <br />25 <br />125 <br />63 42 <br />50 <br />30 <br />180 <br />90 60 <br />50 <br />35 <br />245 <br />123 82 <br />50 <br />40 <br />320 <br />160 107 <br />50 <br />45 <br />540 <br />270 180 <br />50 <br />50 <br />600 <br />300 200 <br />50 <br />55 <br />660 <br />330 220 <br />50 <br />N720 <br />360 240 <br />50 <br />65 <br />780 <br />390 260 <br />50 <br />70 <br />840 <br />420 280 <br />50 <br />Posted Speed, off peak 85' 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. <br />19 <br />