Civil / Site Design
House Creek Greenway Design and CEI, Raleigh
WEI designed, and performed the construction inspection of, a 3 mile section of greenway which begins at Crabtree Valley Trail near the intersection of Crabtree Valley Avenue and Blue Ridge Road, and ends at the eastern end of the pedestrian bridge over the I-440 Beltline at Meredith College. The design constraints included a highly variable grade, transmission lines and towers, coordination within the existing sewer easements, numerous stream crossings, and the need to safely cross 3 roads. The House Creek Greenway provides a link to 2 major components of the existing City of Raleigh Greenway System, and is consistent in design to each of the other trails, while creating a unique experience for the users. A supplemental contract involved a feasibility study and final design for the Ridge Road Greenway section, including negotiation of a Control of Access Agreement with NCDOT.
The structures for this project consist of 3 cored slab pedestrian bridges, 12 modular block retaining walls and and a tree level timber pedestrian bridge. Precast concrete box sections were also used at two locations as the greenway tunnels below city streets.
The project involved widening of the existing sidewalk on the Glen Eden Drive Bridge, and extensive coordination with NCDOT to review alternatives for crossing roads, including I-440, using existing sidewalks through a multi-family unit residential development, and design of a parking and access facility along the proposed trail. Coordination was also needed to resolve floodplain management issues related to the design of significant pedestrian crossings over House Creek, and the concurrent replacement of an existing sewer along the easement to be used for the proposed trail.
Traffic control and pavement marking plans were developed for the construction next to Wade Avenue, Ridge Road and Blue Ridge Road, and the crossings of Horton Street, Lake Boone Trail, Glen Eden Drive and Blue Ridge Road. Three of the crossings, Lake Boone Trail, Blue Ridge Road and Wade Avenue, were NCDOT maintained roads, requiring approval of the traffic control plans.
A section of the trail follows a sewer easement adjacent to House Creek and includes several stream and roadway crossings. Working with the involved utilities, WEI’s design crossed a CP&L power line in two places, a waterline was relocated, the road was cut, and the gas line braced so that it could stay in place during construction. A segment of the trail runs through Meredith College. WEI coordinated with the College on the trail alignment to minimize its impact.
This project involved a detailed analysis of design alternatives, as well as a FEMA CLOMR, buffer and stream impact permits and scour analysis for two new bridge crossings. WEI’s construction estimate was $3,896,672, and the final construction bid was $3,827,380, almost $70,000 under the engineer’s estimate. Our construction estimate at preliminary plans and right of way stages were $3,583,503 (date 11/20/2008) and $4,029,467 (4/23/2009) respectively.
The construction inspection involved backfill placement, subgrade soils, earthwork, cast-in-place concrete, pavement base, asphalt, special inspections (NC Building Code) laboratory testing of soils, concrete and asphalt, reporting, and ensuring that safety was maintained, and that the environmental restrictions were adhered to.