At an intersection the color Red is your friend, Yellow is a cheap ticket to Vegas, and sweet, sweet Green will put the emo on your ipod. Green will devour you. If riding towards an intersection that is Green, the successful rider will soft-pedal in the big ring, in the drops (hoods are ok if the rider can ape Jens or Fabian) until Yellow will allow the rider to sit up with a head-shake of frustration. Remember, "safety first" is your excuse. The successful interval ends with various back and leg stretches while late-braking to a stop. The No-Hand-Arm-Shake-Sit-Up is also appropriate. Never, ever track stand. One back pedal is ok if the bike is still in motion before coming to a complete stop and unclipping one leg only (important!, unless performing the advanced Hampsten Giro TT start-ramp finish).
The meat and potatoes of this workout, as CTS would say, is the Start Line Pose. The unclipped leg is placed straight out, unbent at a forty-five degree or greater angle with the clipped foot at the one o'clock power position (taking up more of the width of the road shoulder, the better). Chain is in big ring and only one thigh or butt cheek rests on the top tube. Forearms are folded or resting on handlebar tops (a classic pose, perfected by Davis Phinney, and one to be mastered before attempting more advanced moves).
Always breathe with your nose at the stoplight and at anytime other riders are in the vicinity.
Never drink from your bottle at the intersection but it is appropriate to unwrap one pre-cut ham sandwich quarter from its wax paper, or to look at a small piece of paper that fits into your palm as if looking at directions. Drinking is ok only when in motion and preferably when riders are approaching from behind at a rate of speed where Wheel-Sucking cannot be attempted as they pass and if the rider is already sitting up. Other activities to practice while being passed or dropped is the Cramp-thigh-Shake (again a Cancellara from Roubaix 2008), sucking down a gel (but never the one stuffed under your shorts thigh gripper), adjusting cable-tension, listening for mechanical drive train gremlins, and very many one legged thigh and back stretches of the Cirque variety.
Starting an interval from the intersection is as important as arriving at one. Green's envy can be reduced by a successful launch. The first move to master is the Neutral Roll-Out; big ring, still chewing, and/or checking the cell-phone are all good roll-out moves until any other riders have overtaken (always start from the front!) and are well ahead. Remember to pull your ear bud out only if spoken to twice, you're concentrating!
Remember always pass a wheel-sucked rider when approaching the Red, prepare for a cramp if the Green is stubborn, and hide your smile when winning Yellow. Use a mirror while on the trainer to practice facial expressions and leg-flex repeats when it's raining. Saturday afternoons are the best time for stoplight intervals. Drive to the area with the most stoplights (Hwy 17 bridge in Los Gatos is the parking place for West Side Santa Clara Valley, and Blossom Hill-Camden-Almaden expressway loop). Behind Bicycle Outfitter for Foothill Expressway, or Roberts Market in Woodside (Canada Rd is good for practicing being dropped + two stop signs!).
Don't smile and have fun!