I-15 South Design-Build: Blue Diamond to Tropicana Avenue

Project Type:
  • Interstate Highway Widening
  • Design-Build
Construction Budget: $246,500,000
Client: NDOT
Service Performed:
  • Utility Coordination/Design
  • Drainage Analysis/Design
  • Traffic Engineering
  • ITS Improvements
  • Signal Design
  • Lighting analysis/Design
  • Structural Design
  • Bridges Design
  • Storm Drain Facilities
  • Coordination

As a subconsultant, GCW provided utility coordination and design, drainage analysis and design, traffic engineering and signal design, lighting analysis and design, and structural design of bridges and storm drain facilities in support of the Design-Build widening project. Project involved extensive coordination with NDOT, CCPW, design team members, contractor, and utilities.

GCW roadway engineers were involved in the urban arterial improvements for one mile of Sunset Road from Valley View to Las Vegas Blvd, including expedited design and coordination to facilitate overall project schedule. Sunset improvements included full depth pavement replacement and rehabilitation, grading design within constraints posed by abutting improvements and ROW limits, storm drain facilities, sewer and waterline relocations, striping transitions, intersection channelization, special overhead guide signing for frontage road conditions, new and modified traffic signals at Windy and Las Vegas Blvd, and ITS improvements. Prepared plan and profile drawings for the relocation of 12-inch sewer main and laterals for the Sunset Road improvements. The work consisted of verifying existing sewer main and laterals by researching plans for existing improvements, having facilities surveyed, and potholing of existing utilities. Project included coordination with utility companies and CCWRD.

GCW flood control engineers performed drainage analysis and design for 14 corridor segments including 2 affected adjacent arterials (Sunset and Warm Springs). Services included Rational Method Hydrology, sizing and spacing of drop inlets, storm drain and channel design, extending existing facilities, and coordination with roadway segments on ditches and swales to convey flow through in-field areas. NDOT criteria were the governing force.

GCW structural engineers developed drawings and calculations for bridge widening and numerous drainage structures. Bridge widening consisted of a single-span concrete bridge on drilled shafts, crossing over the existing Tropicana Wash. Drainage structures include modified drop inlets, concrete box culverts, rectangular and trapezoidal concrete channels, junction structures and a cover slab over approximately 1,990 ft of existing rectangular channel. Cover slab over the existing channel was unique in that the cover slab was not allowed to impact the existing channel owned by the USACE. The cover slab is supported on spread footings running parallel to the existing channel, and a large portion of it will be the riding surface of the freeway.

GCW traffic engineers are provided design including signing, striping, street lighting, and overhead guide signing for frontage road drop lanes, channelization/transition design, large vehicle turn path analyses for dual lefts, channelized right-turn movements, and ITS improvements. Project includes 2 new signal installations and modifications to 7 existing installations. Work included extensive coordination with other design disciplines and maintenance of traffic considerations. Design included sight distance analysis of potential impacts of overhead structures, significant revisions to preliminary plans to reduce costs and improve operations including revised vertical geometry for flatter queuing platforms, and revised horizontal geometry to remove lane merges on curves, remove curvature on the I-15 bridge structure, discourage wrong-way movements, and eliminate severe alignment breaks. Lighting analyses and design encompassed all illumination elements including freeway, streets, underpasses, and guide signs.

GCW provided electrical engineering for traffic-related elements including lighting analyses and design, which encompassed all illumination elements including freeway, streets, underpasses, and guide signs. Work included design concepts for the ultimate configuration to determine lighting systems needed to meet performance specifications, and research and coordination with NV Energy to identify and locate electrical service points.