HVJ Broadway Case Study

Design Build Reduces Disruption in Historic San Antonio

Project Background

The Broadway Street Project

The City of San Antonio initiated a $24 million Design-Build project on Broadway Street from E. Houston Street to IH-35. The project is part of the City’s 2017 Proposition 1 Bond Package which allocates $42 million to reconstruction of the Broadway corridor with “curbs, sidewalks, driveway approaches, bicycle amenities, lighting, drainage, and traffic improvements, as appropriate.”  The work included relocating utilities (sewage, water, etc.), improving drainage systems, providing bicycle facility connectivity, improving landscaping, upgrading traffic signals, and improving the streets after completion of the underground utility work.

Our client, AECOM, provided the civil and utility upgrade designs while SUNDT provided construction services. AECOM subcontracted with HVJ for geotechnical services and pavement reconstruction design services.  HVJ’s geotechnical team evaluated the subsurface conditions and materials to aid in the design of traffic signals and Low Impact Design bioretention structure foundations, provided utility backfill recommendations, pavements required by the scope. HVJ then provided pavement design and construction recommendations.

Practice: Geotechnical Engineering, Pavement Engineering

Sector: Roads

Location: San Antonio, Texas

Services: Field Exploration and Testing, Subsurface Utilities, Shrink-Swell Soils Mitigation, Foundations, Pavement Restoration, Design Alternatives

HVJ Broadway Case Study San Antonio Street

The Problem

Broadway Street is a heavily traveled, arterial street in a historical area of San Antonio with flooding and pedestrian challenges. The city needed this project to be completed with minimal impact to surrounding businesses, the environment, and disruptions to parking and traffic flow. The solution required accounting for stormwater through Low Impact Development (LID) practices to aid with the flooding and provide bicycle access lines for pedestrians. Because the area is a constantly-busy roadway, it wasn’t possible to use retention ponds to manage the overflow problem that caused flooding, so in addition to the storm sewer system, innovative and green drainage features needed to be incorporated.

Due to its age and historical location, the roadway required working around old, abandoned and buried infrastructure and many live utilities before the field exploration and testing could take place. The pavement recommendations also needed to account for varying types of materials underneath the road, including a former trolley line, and be completed efficiently to minimize disruptions to area merchants and other stakeholders such as the VIA transit authority.

The Goal

Our objective was to provide a reliable geotechnical assessment of subsurface conditions for utility installation, foundation construction, and to give recommendations for pavement restoration.  

We were to complete this work in accordance with the Design-Build Program Manual and the City of San Antonio Standard Specifications for Construction guidance, in which the designer and contractor work together to problem-solve collaboratively. Design-Build encourages collaboration and efficiency, as the design doesn’t have to be finished before beginning the work. It requires a high level of responsive communication among all parties involved. 

The Solution

HVJ’s first step was the geotechnical assessment, including testing soil and core samples. There were many utilities in the area, so HVJ’s team coordinated on-site with multiple utility representatives, including those from cable, water/sewer, gas, electrical, telecommunications, fiber optics, and roadway, to ensure no utilities would be damaged through the field exploration process. One intersection in particular was identified as a utility hotel, as it was a highly dense hub of utilities, that we needed to avoid when drilling. Communication was key to providing a safe and danger-free zone when working with these underground utilities.

Samples collected allowed us to provide recommendations for the utility trench excavation. We provided information such as how the ground conditions would affect stormwater and the extent to which soil would shrink or swell when going through the wet or dry cycles. The testing aided with the engineering design for the proposed structures and the pavement at this site.

For the pavement restoration, we used non-destructive testing with the FWD (Falling Weight Deflectometer) to evaluate the pavement properties. FWD testing allowed us to perform multiple tests at the same location and was ideal for determining variability along the roadway. Many measurements were necessary because of the road’s age and inconsistent subsurface conditions.

We compared our measurements with the historical plans to design a hotmix asphalt base layer with an added geogrid to reinforce the pavement. Geogrid strengthens the pavement and slows down cracking, which can occur when streets are widened or repaired. This was needed for managing potential cracking, due to old rail lines encountered beneath the pavement surface. A hotmix asphalt base layer was selected over flexible crushed stone base to reduce dust and delay and to allow the pavements to be used immediately after paving was complete. This solution helped to keep traffic flowing and minimize disruptions to area businesses. 

To ensure the team agreed with the construction of the on-going project and resolution of any issues that arose during the design-build process, HVJ collaborated with all parties involved (including the city, contractor, and designer) during weekly progress meetings. During our involvement in the entire process, HVJ was in constant communication with the design team including emergency conference calls to provide fast and efficient solutions.

The outcome was a successfully completed project with a design that allowed quick completion with limited traffic impact and long-term sustainability that employed innovation. The design enabled utility relocation, provided bicycle access, improved landscaping, new signal light structures and pavement restoration in a manner that would withstand the heavy traffic of an arterial road.

“All deliverables were submitted on time and client comments were responded to quickly. Leo was always responsive, well informed, and professional.”

Kelsey Sconiers
AECOM Project Manager

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