The new wall had a minimum width of 2¹⁄₂ ft. at the top, and 4 ft. at the base of rail, and was provided with weep holes at intervals. To facilitate matters, work was carried on simultaneously at two or three different places, the intention being to get one place torn out and ready for the bricklayers by the time they completed a section of the new wall at another place. In rebuilding the arch, sections extending from the springing line up as far as was necessary to obtain the desired clearance, and from 2¹⁄₂ to 4 ft. in length, were removed. Near the sides, the earth above the arch was a stiff clay, which was self-sustaining; but near the center there occurred a stratum of gravel and clay saturated with water. This gave considerable trouble, falling through almost continuously until timbering could be placed. One end of this timber rested on the old arch, the other on the adjoining section of the new work. As the new work was to be set 6 to 13 ins. back from the old, it was necessary to block up this distance on top of the old arch, to carry the end of the lagging timber, in order that the timber should be clear of the new arch. Owing to the small clearance between the car roof and the arch, a special form of centering was required, one that would occupy as small space as possible. Bar iron 1 in. thick, 4 ins. wide, and 20 ft. long was curved to a radius of 6¹⁄₂ ft., and on the underside of this was riveted a 6-in. plate ¹⁄₄ in. thick. This plate projected 1 in. on the sides of the centering, and carried the ends of the 1 in. boards used for lagging. The rivets were counter-sunk on the outside of the centering to present a smooth surface next the arch. In keying up a section of the new work, a space about 18 ins. square had to be left open for the use of the workmen. As soon as the next section had been torn out, this space was built up. In building up the last section, this space had to be filled from below, which proved to be a tedious undertaking. The opening was gradually reduced to a size of 10 × 18 in., and the top ring then completed and keyed up, the adhesion of mortar holding the bricks in place until the key could be driven home. The next ring was treated in a similar manner, and so on to the face ring. Altogether 412 lin. ft. of the walls and 178 lin. ft. of the arch were taken down and rebuilt, amounting in all to 607 cu. yds. of masonry at the total cost of $7,440, or about $12.25 per cu. yds.