What is the standard loading value used for design trucks?

• A. 10-ton
• B. 15-ton
• C. 25-ton
• D. 20-ton

Answer: (D)

In bridge design, a standard design truck weight is used as a representative live load to gauge how a deck and its supporting members respond to moving heavy vehicles. This weight is chosen to reflect the kind of trucks commonly seen on highways while giving designers a consistent basis for checks across projects. The 20-ton value has become a standard because it provides a realistic yet practical benchmark: it’s heavy enough to produce meaningful bending and shear effects without pushing every bridge into overdesign. Using this value also simplifies loading models, allowing straightforward evaluation with either a single concentrated load or a set of wheel loads that approximate how a real truck interacts with the deck. While some codes may use other designs for special cases, 20 tons is the conventional design truck weight in many practice contexts.