It's not easy to answer without seeing a picture or a plat. If it's a publicly owned alley, then he really has no basis to complain about traffic using it. If it's privately owned, he might have something to complain about. Even if it's privately owned, many times those alleys are governed by some sort of written and recorded easement agreement that spells out some rights and responsibilities. Before you spend more money fixing the roadway or time in dealing with your neighbor, you should gather up as much information as you have about the title to your property and the alley and bring it in to a local lawyer knowledgeable about land use and title issues. Hopefully you'll find someone who'll consider what you're doing and show some charity toward the fees. Good luck, and keep doing the right thing to help the needy.
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If your - or that of your agents or invitees - use of the ally causes a recurring trespass and damage to the neighbor's property, he might have a cause of action.
I am not a IL attorney, laws vary from state to state, therefore you should always consult a local attorney.
If this answer was helpful, please mark it as helpful or as a best answer. This answer is for general education purposes only. It neither creates an attorney-client relationship nor provides legal guidance or advice. The answer is based on the limited information provided and the answer might be different had additional information been provided. You should consult an attorney.