When the travers (haunches-in) is performed at the walk or trot along the railing of the arena, the horse's haunches are pressed toward the inside of the ring by your outside leg. When traveling counterclockwise, the aids for the travers are:
To move into a left haunches-in from a straight-away, your right leg slides back into position and presses the horse's haunches off the track, while your hands move into a left indirect rein position, bending the horse toward the direction in which it is traveling. (If the horse resists the left indirect rein by stiffening its shoulders, use an outside opening rein to guide the shoulders toward the right, into the correct position.) Your left leg complements the left rein in sustaining a uniform bend throughout the animal's body and drives the horse forward in the movement. Your right leg holds the haunches off the track, while your right hand prevents the horse from rushing and works with the left hand to control the degree of bending.
In the haunches-in, the horse's body is approximately at a 30-degree angle from the wall, but the haunches are bent slightly more around the rider's leg than when performing the shoulder-in, so that the animal's feet travel on four tracks, instead of three. (Originally, the haunches-in was a three-track movement, but because of the difficulty of judging the less obvious degree of bending, the movement was changed to four tracks for dressage competition.)
To straighten the horse after the left haunches-in, bring its shoulder in line with its haunches by moving both of your hands to the left and resuming a direct rein; then press the horse sideways, back to the railing, with a leg-yield.