twork element. A carrier who requests unbundled access to the local loop needs to be able to terminate that loop by connecting it to the requesting carrier's switching equipment. As result, the 1996 Act included collocation requirements that were quite similar to those adopted by the FCC in its Expanded Interconnection proceedings. Specifi- cally, the statute requires incumbents to permit "physical collocation of equipment necessary for interconnection or access to unbundled network elements." When technical considerations or space limitations render physical collocation impracti- cal, incumbents need only provide virtual collocation (47 U.S.C. § 251 1(c)(6)). The FCC implemented the local competition provisions of the 1996 Act in a massive order issued just three months after the statute's enactment. The FCC imple- mented the provisions governing interconnection and UNE access rates through a methodology known as TELRIC, which bases rates on the element's "economic costs," defined as the sum of the incremental costs directly attributable to the specified element and a reasonable allocation of common costs. TELRIC's most distinctive feature was the fact that it assessed both the incremental and common costs on a forward-looking basis by focusing on what it would cost to replace a par- ticular network element rather than its historical cost. TELRIC avoids the problems caused by the distinction between fixed and variable costs by measuring incremental costs from a "long run" perspective, which is defined to be a period long enough SO that all of a firm's costs become variable or avoidable. The FCC believed that basing rates on forward-looking incremental cost represented the best way to replicate, to the extent possible, the conditions of a competitive market. In addition, TELRIC further accommodates technological change by requiring that costs be determined on the basis of the most efficient technology available and the lowest cost network configuration given the existing location of the incumbent's current wire c