They force pedestrians to pay attention.

We don't know why the individuals were on the tracks.

We don't know why the driver made the decision to cross. It appears that everything was working properly. Again, that's all under investigation.

We don't really know what her motivations were. Right now we only know what the results are. Drivers need to take very seriously a crossing arm.

She drove around the crossing gates, apparently. The gates were down and everything was functioning as it was supposed to.

The fence in itself is a force multiplier. It allows Border Patrol agents to refocus their attention to other areas because it won't require as many Border Patrol agents to monitor a location as it would without a fence.