To some specifiers and owners who want to get the best pavement buy for a highway, street or parking lot, the method for choosing between concrete and asphalt seems simple. Prepare designs that are equal; take bids; and award the contract to the lowest bidder. What could be simpler? To take a close look at that approach, let's ask one key question. Can pavement designs for these types of pavement ever be equal when one of them--concrete--can be designed for a longer service life, is less costly to maintain, and will provide better riding quality, skid resistance and nighttime visibility during its life? The answer is no. So-called equal designs don't produce pavements of equal performance.

Consistent with sound engineering practice, the merits of concrete pavement will best be recognized when selection of pavement type takes long-term performance into account. The selection should be based not on initial cost only, but on a cost comparison that takes into account initial cost, anticipated service life and surface and base maintenance costs.

A life cycle cost analysis is now being used by many state DOT's. It starts with a total cost analysis for each pavement type, taking into account initial cost, future maintenance and rehabilitation costs. The same analysis period is used for each pavement, up to 35 years in many states. Life cycle costing has been expanded to include the economic analysis of present worth. Present worth, as applied to pavement construction, is described as a means of expressing all costs incurred during the service life of a pavement in equivalent dollars.