Regarding the posted speed for turns, which statement is true?

Regarding the posted speed for turns, which statement is true?

• A. It is always safe for buses
• B. It may be unsafe for buses
• C. It is always unsafe for all vehicles
• D. It has no impact on safety

Answer: (B)

Turn speed must be matched to vehicle dynamics. The posted speed for a turn is chosen to be safe for typical traffic, but for a bus it can be unsafe because of its size and weight. Buses have a higher center of gravity, are much heavier, and have a longer wheelbase, all of which make steering less responsive and increase the risk of rollover or loss of control during a turn if taken at speeds not suited to these characteristics. They also need a larger turning radius and have longer stopping and acceleration times, which means a turn that’s acceptable for smaller vehicles can pose greater danger to a bus, especially in adverse conditions or when loaded with passengers. Therefore the statement that the posted speed for turns may be unsafe for buses captures the real risk. The other options aren’t accurate: it isn’t always safe for buses, because safety depends on the vehicle and conditions; it isn’t always unsafe for all vehicles, since cars can often handle the posted turn speed under good conditions; and it has a clear impact on safety, which is precisely why drivers adjust speed.

Turn speed must be matched to vehicle dynamics. The posted speed for a turn is chosen to be safe for typical traffic, but for a bus it can be unsafe because of its size and weight. Buses have a higher center of gravity, are much heavier, and have a longer wheelbase, all of which make steering less responsive and increase the risk of rollover or loss of control during a turn if taken at speeds not suited to these characteristics. They also need a larger turning radius and have longer stopping and acceleration times, which means a turn that’s acceptable for smaller vehicles can pose greater danger to a bus, especially in adverse conditions or when loaded with passengers. Therefore the statement that the posted speed for turns may be unsafe for buses captures the real risk.

The other options aren’t accurate: it isn’t always safe for buses, because safety depends on the vehicle and conditions; it isn’t always unsafe for all vehicles, since cars can often handle the posted turn speed under good conditions; and it has a clear impact on safety, which is precisely why drivers adjust speed.