I see what you mean, you're probably right that it would help, but honestly I just don't think the people hitting it are reading it in the first place. It doesn't light up until they're at the intersection, at which point they're either very focused on the light or the traffic, and definitely not looking way above even the yellow bar. Most people seem to be driving rentals, and in their case they're just not thinking about the size of their vehicle, and the rest have gone under a thousand bridges that look to the unfocused eye just as tall, so they're not worried about it at all. What they really need is probably just something that hangs at that height in front of it so you can hear it bang off of your car with minimal damage before you actually hit the bridge, and push the intersection further away from the bridge so there's more time to look at the signs.