Another construction challenge involved the weather in the region. Wang Yong, chief director of the Hangzhou Bay Trans-Oceanic Bridge Construction Command Post, described the bridge as being built "in the world's most complicated sea environment, with one of the three biggest tides on Earth, the effect of typhoons and the difficult content of the sea soil." Erosion of materials and cracking and bubbling of any concrete components became a large problem. To combat bubbling and eventual holes, engineers used a cloth-covered template over the concrete. This would improve the color and density of the pieces, making them both more aesthetically pleasing and sturdier. To reduce cracking, engineers used low-strength early-stretching technology when constructing box girders. This technology involves casting (molding) the girder, or bridge panel, letting it harden for no more than three days, and then squeezing it before it reaches its full density. This gives the girder more room to stretch after the bridge is constructed, preventing cracks in the concrete over time.