Project of the Year - Site Landscaping

South Riverwalk Park

A project that puts six acres of park on top of a major vehicular tunnel seems good enough to earn one word from the awards jury: "Spectacular."

Another juror called the South Riverwalk Park project in Trenton, N.J. "a grade-separation project that's pretty substantial."

That could be an understatement. Getting the drainage just right was critical. Also critical was selecting the right kinds of soil, plants, and trees, as well as accurately estimating the structural load that the park would put on the tunnel structure.

The end product meets the needs of both motorists and the community in one beautifully landscaped park. It improved traffic flow, beautified a long stretch of riverfront, and created a point of pride for the residents of the nearby neighborhood.

advertisement

The $10 million park tops off an earlier, $105 million project to improve 2 mi. of a busy highway that ran just feet from the front yards of an historic Trenton neighborhood. Route 29 is a busy four-lane highway running along the Delaware River. North of its intersection with Interstate 295, Route 29 used to spill directly onto residential Lambert Street, lined with mature trees and century-old brick row houses. The daily flow of heavy traffic depressed property values, in spite of the proximity of the river and a new minor league baseball stadium a few blocks away.

In 1996, the New Jersey Department of Transportation began design work on what would become a multiyear project to keep highway traffic off Lambert Street, routing it instead into a new, half-mile-long cut-and-cover tunnel. When the tunnel opened in 2002, it improved the flow of traffic on the road and rescued Lambert Street residents from the heavy traffic.

The tunnel was an improvement, but it was still a barrier separating residents from the waterfront. To help connect them to the water and provide much-needed green space, engineers set out to make the link a city park.

Building a park atop a tunnel is not a standard construction job, and it required the contractors, more accustomed to highway work and heavy-construction methods, to adjust their approach and integrate nonstandard materials into the project.

The design team, led by New York City-based Vollmer Associates, worked early on to engage residents of the nearby neighborhoods, which are bereft of parks. The residents expressed a strong desire that their tunnel-top park have both passive and active green space.

But the unusual shape of the site made that difficult. The park is long and narrow, about a half-mile long but just 150 ft. at its widest point. Such dimensions all but ruled out traditional ball-playing fields.

The designers split the difference by cutting the park in half, with separate areas for passive and active recreation. The quieter southern half features winding paths, a small pavilion, benches, and areas of wide grassy lawns. The northern half has a pair of playgrounds, two larger pavilions, and a large open paved area that can host community events.

Since the tunnel is only partially below grade, the park itself is slightly higher than Lambert Street. That meant the park needed numerous entrances. The team placed grand sloping pathways at both ends of the park, with other points of entry at several spots along the park's length.

A riverside promenade also runs the length of the park, and the two halves join in an interpretive area devoted to Trenton's history. It features five octagon-shaped plaza sections, each representing a century of the city's past, with wide brick archways crowning them and allowing visitors to pass underneath.

South Riverwalk opened earlier this year to glowing reviews from more than the jury members. Residents of Lambert Street have flocked to the park and taken proactive steps like forming neighborhood watch patrols to keep their new park clean and safe.