When estimating the live load for a new bridge design, you want that estimate to be conservative. In other words, you want to error on the safe side by basing the estimate on the worst possible scenario—for example, bumper-to-bumper traffic, the heaviest vehicles, the worst environmental conditions, etc. With this in mind, estimate the live load for the following proposed bridge designs:

a. A foot bridge with a 174. ft span and two separate 4. ft wide lanes to allow for pedestrian traffic in both directions.

b. A four-lane highway with a 300. ft span.