Will your Horse Pass?
Certain precautions need to be taken in order to determine that your horse has been trained to drive a horse vehicle, cart,carriage, or wagon, or if you have a horse that has not been driven in a long time. You  should perform certain tests prior to hitching up a horse vehicle and taking off. You will need two to three other people to help you with these tests. First you will want to start with ground driving your horse to see how well he reacts to your rein aids. Stay at this level until you are confident that your horse responds well to the gentle pressure you apply to the reins. This might take a few hours to a few months until you will know your horse is comfortable in the harness, the horse responds well to voice commands of walk, trot, whoa and back. They must be able to stand quietly for long periods of time.
                                                                                                                                   

Introducing the carriage to Your Horse  

Once you know that your horse can perform all the above exercises without any trouble whatsoever, and all movements are smooth, responsive and consistent before you introduce your horse to a vehicle, cart,carriage or wagon. Carts are much easier to operate and train a horse with. Wagons are harder than carts to maneuver and can tip over if turned too sharply.  Slowly introduce your horse to the cart or vehicle you are eventually going to hitch him up to but do not hook the horse up yet. This is where you will require some help. Someone will need to lead your horse while two other people pick up the shafts on the vehicle and place them on either side of the horse. You will want to position yourself with the reins in hand behind the horse on the side of the cart as if you were in the vehicle driving the horse. This might take some time to get your horse comfortable with the sound of the vehicle, the shafts touching it’s sides and comfortable with something following behind. Only then should you insert the shafts into the backsaddle tugs with the traces still unhooked, in order to let the horse feel the weight of the cart. Once the horse accepts the weight of the cart at its sides at this point the traces can be hooked. Make sure there is someone holding a halter and lead over the bridle at the horses head. With the two people at each side of the vehicle in case the horse needs to quickly be unhooked from the traces. You will still be in the driving position with the reins. Get in the drivers seat ONLY when your horse is calm and quiet with the vehicle, turns and responds willingly. When you do enter the drivers seat you will need your aids at the head of the horse with halter and lead and at each side. Do this until the horse is comfortable with your added weight in the vehicle and will respond to all your voice commands as you did when ground driving.  Remember, not all horses, no matter how well mannered under saddle, will be well mannered under harness so evaluate your horse objectively and don’t try and make him into a driving horse when he is not. You will save yourself and your horse a lot of frustration if you recognize this early on.

There’s Still A Lot of Ground to Cover
The above exercise will get you in the cart but you are far from being able to take off on the open road. You need to make certain that your horse is steady with the cart in traffic and to any obstacles that might come it’s way. You want to make certain that your horse will keep going forward with the vehicle attached, no matter what the obstacle might be. It could take a long time before you are to the point you can go on the open road. Take your time and make sure you and your horse are ready. You want to avoid a wreck at all cost. Take necessary safety precautions, like wearing a helmet. Take it slow, make sure you and your horse are both confident and above all stay safe while driving your horse carriage.