The Convoy crossing the ice

If the ice is so dangerously thin that it was cracking underneath their tires as they drove, why would they think it's a good idea for all five vehicles to cross at once? That seems like that just makes it even more dangerous, why couldn't they just do one vehicle across at a time? I know it would take longer but still it seems safer than loading thousands of tons onto the ice at a time. Although that probably would alleviate too much drama and tension to make good TV.