There's no street lighting on this road. You can't use speed bumps in unlit areas (because drivers won't see them at night until it's too late to avoid vehicle damage).
>Speed bumps are a reasonable idea in terms of being a low-cost intervention, but regulations permit their use only under street lighting, so they cannot be used here.
Also (adding more detail): The reason why you can't install lights is because there aren't any wires for the electrical grid, so that would cost a lot of money to add, and the locals would likely object to the extra source of light pollution.
