large letters on three buildings. Although Trump ceased his active involvement in the development in 2001, he retained his 30% limited partnership. The Buildings Department discovered in November 1997 that defective concrete had been used in the capitals of columns supporting the fifth floor of 300 Riverside Boulevard, which had been built to 20 stories high by then. Fearing that the planned 46-story structure might collapse if the building rose to even 30 stories, the City halted construction. Work on 300 Riverside Boulevard resumed in early 1998 after the defective concrete was torn out and new concrete was poured. West Side Highway relocation One of the key components of Riverside South is relocating the West Side Highway eastward from a viaduct to a rail-yard-grade-level tunnel between approximately West 70th Street and West 61st Street to facilitate a southward expansion of Riverside Park. The current viaduct between 72nd and 59th Streets is the only remaining section of the West Side Elevated Highway that once ran to the southern tip of Manhattan. The highway closed in 1973 when part of the 1920s- and 1930s-era elevated highway collapsed at 14th Street. Below 34th Street, the proposed replacement, an interstate highway in new landfill known as Westway, was defeated, so in 1988, the state settled on an at-grade boulevard up to 57th Street flanked by a new Hudson River Park. Robert Moses had proposed relocating the highway between 59th and 72nd streets to grade to facilitate an extension of Riverside Park. But the state rejected that proposal because of the presumed negative effect on development opportunities and because it would violate the Blumenthal Amendment, which prohibited any highway construction that would alter Riverside Park. In 1976, Donald Trump seized on Robert Moses' proposal as a way to enhance his development plans, negating one of State DOT's objections. But cost was still an issue. While the state owned an easement through the site, neither the state nor the city (nor Trump, at that point) owned the land. Although the City could have acquired the land in the 1970s from the bankrupt Penn Central, the City was near bankruptcy itself, and consequently preferred to keep the site in private hands to forestall demands for public expenditure. Trump's proposed 12,000-unit residential development went nowhere. So the state proposed to reconstruct the viaduct through the rail yard site. With city approval in 1992 of the Riverside South plan,