A frontage walk in this city goes wrong in one of two directions, and which one it takes is decided before anyone pours anything, by where in Anaheim you happen to stand.
West of the freeway and across the old colony grid, the map unit under a frontage is Metz loamy sand out toward Beach Boulevard and San Emigdio fine sandy loam through the middle of the city, close to 70 percent sand against 13 percent clay. Linear extensibility runs about 1.2, so this ground barely swells. What it does instead is travel. It holds no cut face, and irrigation running along a joint carries it out from beneath the edge until the panel spans air and drops.
East of Imperial Highway the mechanism inverts. The canyon pads are mapped Alo clay, half clay by weight, and it rates 9.3 for linear extensibility, the profile genuinely changes volume between a wet February and a dry September. Concrete does not, so the walk is lifted and set down twice a year until a joint steps. Depth and joint layout are what absorb that, which is why the Portland Cement Association ties saw spacing to slab thickness rather than to a fixed distance.