US 29 Median Widening
Howard County, MD
AMT provided conceptual to final design services, including preparation of contract documents for improvements to US 29 for approximately 3.2 miles, from MD 32 to MD 175, which included: widening to add a third northbound lane on the inside shoulder for the section of roadway within the project limits; alternatives analysis for design modifications to the US exit ramp to MD 175; and a Safety and Capacity Study to identify a design alternative to eliminate the existing at-grade intersection of US 29/Rivers Edge Road and replace with a grade-separated alternative. Specific services provided include: Roadway Reconstruction/Widening – Roadway Design – Prepared contract plans for the roadway widening and coordinated the design of drainage, SWM, erosion and sediment control, MOT, TMP, noise abatement measures, landscaping, and signing and pavement marking designs. Typical sections were modeled to determine the model surface, slope limits, grading, quantities, and cross sections. Superelevation of the existing road was modified to meet current standards. Bridge clearance calculations were checked for minimum clearance allowance under existing structures. Grading to accommodate median ditches and SWM features were incorporated into the cross sections. Along with widening, the project required a sound wall to be constructed to meet noise level requirements for adjacent residential areas. Other design features included changes to storm drainage, design of additional of SWM features, and maintaining sufficient shoulder widths to accommodate bicyclists. The final submittal included plans, specifications, and cost estimate for final advertised plans; Maintenance of Traffic – MOT plans included two main phases of construction and were prepared in coordination with the phasing of the erosion and sediment control plans; Utility Coordination – Extensive utility coordination was required to plan for relocation of water lines. Sound wall locations were shifted and supports moved to avoid impacts to existing utilities.