Hot rolled and cold formed are two primary methods ofmanufacturing sheet pile. While there are differences between these twomethods, the most important distinction is the interlock. Since hot rolledsheet piles are produced from steel at high temperatures, the interlock tendsto be tighter than its cold formed counterpart. Normally, looser interlocks arenot recommended in extremely hard driving conditions or for walls requiring lowpermeability. Otherwise, the two types of sections perform similarly in mostapplications. U sheet piles retain soil and water just like Z piles with one important difference: U piles have the interlock on the neutral axis. The placement of the lock in the centerline of the wall reduces the efficiency of the section and can cause reduction of section properties because of shear transfer problems. The AU and PU sections are some of the most efficient U pileson the market. The AU series is very wide, making it an excellent option forenvironmental applications.