of Merit - Highway
Route 31 Dualization
Highway construction and environmental friendliness may
seem to be contradicting terms, but the Route 31 Dualization
Section 6E/6F project in Raritan and Readington, N.J. offers
"They addressed floodplain issues at the same time
as they were developing a highway," one judge said.
The goal of the $29 million project was to improve conditions
of Route 31, a two-lane undivided north-south highway in Hunterdon
County, N.J. It has daily traffic counts exceeding 33,000
vehicles and a 50 m.p.h. speed limit.
The project improved 2.3-mi. of roadway from River Road
in Raritan Township south to Stanton Station Road in Readington
Township. The program included widening the road, changing
the roadway profile, installing concrete median barriers,
and providing inner and outer paved shoulders. It also replaced
two structurally deficient bridges and a culvert used for
drainage and as a pedestrian underpass.
The southbound roadway runs parallel to land within the
Hunterdon County Park System, which is primarily wooded or
wetlands. At the northern point of the project, the roadway
runs parallel to the south branch of the Raritan River. The
northbound roadway runs parallel to a steep rock slope.
The roadway also meanders to avoid or minimize impacts to
numerous environmental resources, including the historic Hoagland
Brittin Farmstead, various sites at Rowland's Mills, and park
system hiking trails. The design and construction phase included
archeological data recovery at the Rowland's Mills site to
avoid impact to historic elements. The phase also involved
a local education outreach program.
Once work commenced, the team took on several big tasks,
including replacing the culvert that provided a pedestrian
crossing of Route 31 for the Irvington School District Outdoor
Education Center. In its place, the team built a 130-ft.-long
lighted pedestrian underpass compliant with the Americans
with Disabilities act.
The team also built three retaining walls to reduce the
required embankment within the existing floodplain and wetland
along the southbound roadway. The walls also limited the need
to excavate into the rock slope along the northbound roadway.
One was a 2,200-ft.-long by 15-ft.-high median retaining
wall to accommodate the split northbound-southbound profile.
A second was 210-ft.-long along a bend in the Raritan River.
Since shallow rock prevented drive sheeting, the team used
a porta-dam system during construction to keep debris out
of the river and protect the habitat from exposure to toxins
released through concrete curing.
The walls didn't eliminate all need for excavation, however.
The rock work was a big challenge, including one phase along
the northbound side where a discontinuity in the underlying
rock resulted in a slope failure during construction. The
team halted work and shifted gears to explore other solutions,
which entailed getting additional right of way to re-grade
to flatter, more stable slope.
"They were very sensitive to the environment and to
the landscape," one judge said.
Another big job was replacing the two bridges, one a 165-ft.
span over Conrail railroad tracks and the other a 275-ft.
long curved girder bridge over the river's south branch.
The retaining walls, bridge piers, and wingwalls have concrete
tinting and ashler stone finishing treatment to enhance their
appearance and integrate them into the surrounding environment.
The design of the bridge parapets mimics the historic balustrades
of the original spans.
The project also met the specialized needs of the greater
community, including a request from the New Jersey Division
of Fish, Game and Wildlife to maintain a pathway and leave
adequate headroom for hikers and equestrian riders at the
abutment and underclearance for the Raritan River bridge.
The project team also coordinated with the state Department
of Transportation's Bureau of Landscape and Urban Design to
ensure that concrete tinting blended with native rock in the