However, the section between 9th and 19th Streets soon experienced various delays: although it had started in April 1961, work was halted by a water main break in 1962, and by July 1963, the work was only 20 percent complete. Construction on the section between West 19th and 31st Streets was further along: it had started in the middle of 1961, and was 60 percent complete in July 1963. The first section was 88 percent complete on June 30, 1965, and the second section was 99 percent complete on that date. Between West 55th and 58th Street, a third of the structural work was done by this date. No stations were constructed along the new express tracks, but provisions were incorporated into the design of the tunnel to permit the addition of future lower level stations at 14th Street and 23rd Street without disturbances to train operation.