Final answer:
An 'exit only sign' over highway lanes signals that the lane must be used to exit the highway; drivers cannot continue on the main road in this lane. A 'load limit sign' on a bridge indicates the max permissible weight to protect the bridge's structure.
Step-by-step explanation:
An exit only sign that hangs over highway lanes indicates that the lane directly below the sign is designated for exiting the highway only. Vehicles in this lane are required to leave the highway at the upcoming exit, and they will not have the option to continue on the main stretch of the highway beyond this point. The purpose of the exit only sign is to inform drivers in advance so they can prepare to exit or change lanes if they do not wish to leave the highway.
Similarly, a load limit sign on a bridge informs drivers about the maximum weight that the bridge can support. Just like there are limits to what can go into an electron orbital or how many people can safely occupy a room, a bridge has a weight capacity to ensure its structural integrity is not compromised.