neighbor contractor drving backhoe on our property. what legal rights do we have?

Unless they have an easement or other access rights, the contractor (and possibly the neighbor) are liable to you for any damages caused - based on the limited facts you have provided. Photograph and document all damages. You should write a letter to both the contractor and land owner putting them on notice of your claim and formally demanding that they stop. You may want to consult with an attorney to have them review the circumstances and write a letter on your behalf. You also likely have the right to sue if you are note able to resolve this through negotiations.