What is the primary danger when riding a motorcycle across metal bridge expansion grates or steel utility plates in the roadway?

1. Smooth steel plates have virtually zero traction, causing tires to slide sideways or slip instantly if braking or cornering
2. Steel expands in heat and will buckle under the weight of a motorcycle
3. Metal decking interferes with the machine's electrical system
4. The ridges in the plate will grip the tyre too strongly and stand the bike upright