Combined Driving Events, or CDE's, are modeled after Combined Training.  In the end, the competitor with the lowest number of penalty points is the winner. 

Phases: Dressage, Marathon, and Cones.

Levels: Training, Preliminary, Intermediate, and Advanced

Dressage – Driven in a 100x40 meter (or 80x40) ring, the driven dressage test includes walk and trot transitions, halts, rein backs, circles, extensions, diagonals, and serpentines.  Competitors wear formal turnout.  (see below)

Marathon – This phase can be compared to cross-country jumping, without the jumping.  The course instead consists of a series of hazards.  They have lettered gates and are spaced out over 2.5-14 miles through fields and woods.  In Training level, there are three sections: a trot section, a walk section, and the hazards.  The event is timed, a navigator must ride with the driver, and they wear marathon dress.  (see below)

Cones – This phase is similar to stadium jumping, where fitness and endurance are tested.  While the event is also timed, precision and accuracy are more important.  There are twenty pairs of cones, each with a ball on top.  Each competitor’s vehicle is measured and the distance between the cones is reset for each competitor.  The spacing is 16-20 inches outside the wheel width for lower levels.  Penalties are accrued by knocking down a ball (3 pts.) or exceeding the time allowed.  For Training, the time is 180 mpm.  (formal turnout)

Turnout

Etiquette and tradition come from England and are very important to carriage driving, and the complete rules are published in the ADS rulebook.  (Some of the rules do seem silly).  I have a country turnout, because my horse has a low, ground covering stride and gives the impression she could provide a nice drive through the country.  So, with a natural varnished vehicle, such as my road cart, I can have a black or russet (brown) harness, with chrome or brass trim.  (With a painted vehicle, you must always use a black harness).  Whichever leather color is chosen, it must be the same throughout. 

I wear a more informal turnout, which is a straw hat, vest or jacket, driving apron, brown gloves, and a whip.  In Marathon, competitors wear jeans or khakis, boots, gloves, whip, helmet, and a polo shirt or windbreaker.  The navigator should match his/her driver.

American Driving Society - americandrivingsociety.org

Maine Driving Club - mainehorse.com/mdc

Running Brook Farm - runningbrookfarm.com

Camptown Harness - horseharness.com