Vehicles speeding in South Road

We live in the unadopted part of South Road opposite North Road. Our road is narrow, doesn’t have footpaths, drains or lighting, it’s a no through road but we have a constant problem of vehicles being driven at inappropriately fast speeds for the single track road with blind driveways that it is. Could the entrance to the road that is on Highways land be marked with something like “Please Drive Slowly 10mph”? We already maintain the road ourselves and don’t get any reduction in our council tax for not having lighting, drains or footpaths so could we please have some help in making our road a safer place to live. Thank you.