After a frightening incident with a 4 x 4 my horse has become very nervous of all vehicles. I took her to a livery yard last summer and she had a paddock near a road and I thought she was getting better. Most of the hacking was off road.Then she turned tail and cantered off down the road with me when she saw a truck with a large coiled pipe on the back. A week later I was on a track some distance from the road when a car whooshed past from behind and we ended up galloping across a wheat field. I took her home for the winter and now only ride her in the school which is very disappointing. We are on a farm and one corner of the school is near the cow barns with various tractors etc passing by. We usually stand and look from half way up the school and she is ok. But when a 4 x 4 drove past today we ended up spinning and cantering off to the other end of the school. Can anyone advise me on how I can get her trust back.