Page:Final Report - The Columbia River Interstate Bridge.pdf/50

, and the similar construction on the opposite side of the slough had been completed and was standing satisfactorily. Additional embankment was placed for the portion which had subsided. The pier was then repaired and replaced with additional foundation piles and new concrete, and the entire construction was ﬁnished without further slides or disturbances.

The pavement construction was somewhat unusual. As the embankments were practically pure sand, ordinary methods of preparing the subgrade could not be followed. The specifications provided that the Contractor might either add clayey material to the sand surface in such amounts that the subgrade could be formed and rolled, or else merely shape up the sand to correct surface and then pour on enough water to pack the sand similar to a wet sand beach, hard enough to deposit and roll the stone, keeping the sand "continuously and thoroughly wet, hard, and firm until and during the placing of broken stone or concrete." The latter alternative was followed, but the broken stone base was rolled only lightly, as continued rolling caused the stone to work to the sides, and after the base had been shaped up by the light rolling a cushion coat of bitulithic paving mixture was applied and the whole thoroughly rolled. The placing of the bitulithic surfacing by standard methods followed immediately.

The matter of Franchises for the operation of cars over the bridge came to the attention of your Commission soon after the construction of the bridge was started. At your meeting of April 30, 1915, you appointed an advisory committee on franchises, consisting of District Attorney Walter H. Evans of Multnomah County, Prosecuting Attorney James O. Blair of Clarke County, and Consulting Engineer Ernest E. Howard. Your Engineers prepared a tentative draft of a franchise which was submitted and critically passed on by the other members of the advisory committee, and after the submission of several reports by this advisory committee, with extended discussions by your Commission and representatives of the various traction companies interested in the tentative drafts submitted, your Commission on September 1, 1916, adopted a general form of fran-