The Triangle boasts hundreds of miles of greenway, including more than 100 miles of walking and biking trails. The Crabtree Creek Greenway is designed to link the City of Raleigh’s greenway system with Umstead State Park in Cary. WithersRavenel has provided planning, engineering, and design services for two major portions of the greenway.
For the original segment of the greenway, WithersRavenel evaluated potential trail alignments immediately west of Duraleigh Road in Raleigh. Portions of this land are considered mountainous terrain, which requires multiple vertical alignments. Although designing trails parallel to streams normally does not involve grades in excess of 1%, one trail corridor along Crabtree Stream involved a 23% grade. WithersRavenel developed a computer model to simulate walking on the trail to verify that it conformed to ADA guidelines for accessibility.
WithersRavenel also provided surveying, design, easement maps, permitting and bidding support, and post-construction-award services for the original trail segment. The permitting effort was extensive and included a Conditional Letter of Map Revision (CLOMR), Clean Water Act Section 401/404 permits, encroachment permits, and erosion and sediment control permits; WithersRavenel worked with the Federal Emergency Management Administration (FEMA), U.S. Army Corps of Engineers (USACE), North Carolina Department of Water Resources Division of Water Quality, North Carolina Department of Transportation, and North Carolina Department of Land Resources (NCDLR).
The other major portion of the greenway is a 2.25-mile-long segment extending from Black Creek in Morrisville, along the southern edge of Lake Crabtree in Cary, to Evans Road and Aviation Parkway back in Morrisville. WithersRavenel provided surveying, hydraulics/hydrology, landscape architecture, environmental and wetland delineation, design, cost estimating, and permitting for this segment.
Because the trail passes through areas of floodplains and wetlands, the WithersRavenel team designed a number of bridges and boardwalks. A signature element of the design is a new 730-foot-long boardwalk over the southern extension of Lake Crabtree where Black Creek flows into it, which will provide an out-of-the-ordinary trail experience in an area where trail users enter Umstead Park near the Weston development in Cary.
The American Council of Engineering Companies (ACEC) of North Carolina awarded WithersRavenel a 2019 Engineering Excellence Award for its innovative achievements on the recently completed 1.7-mile section of the Crabtree Creek Greenway that runs along Lake Crabtree in Cary.