A&O’s foundation is grounded in bridge design, with deep and varied experience among the professional staff. Our experience with new bridge or replacement designs have included conventional construction materials of reinforced concrete, precast prestressed concrete, and structural steel. We have provided design services for small bridges along rural roads as well as multi-level urban interchange curved-girder steel bridges.

A&O has performed NBIS (National Bridge Inspection Standards) bridge inspections since 2000. Our methods include non-destructive field testing, in-situ concrete testing, core sampling, chloride testing, and hands-on inspection.

We are registered with NCDOT as a small professional services firm (SPSF). Six of our inspectors are team leaders, certified by the Federal Highway Administration and the National Highway Institute, with a combined total of more than 100 years of experience inspecting bridges. The teams are proficient in the use of NCDOT’s WIGINS reporting software and use Microsoft Surface Tablets to report conditions from the field.

In keeping with A&O's core value of stewardship, we see bridge preservation as a way to save our clients money over time. With routine inspections, detailed assessments, and non-destructive testing, we discern existing conditions that contribute to accelerated deterioration, whether from leaking joints or chloride penetration that leads to active corrosion. We assist the state in prioritizing maintenance and repairs to maximize the life of each bridge by up to 50 years.

Bridge preservation may include concrete repairs, bearing replacements, structural steel repairs, bridge superstructure jacking, deck surface repairs, bridge joint replacements, pile repairs or replacements and concrete sealers or overlays. All preservation methods are evaluated with regard to life cycle cost and replacement cost so that ultimate replacement of the structure may be planned.

A&O is experienced in designing a variety of culverts for NCDOT, municipalities, and other entities. Our designs have included concrete arch, corrugated metal pipe, reinforced concrete pipe, corrugated steel plate, corrugated aluminum box, three-sided, and reinforced concrete box culverts. Methods of construction may include pre-cast, cast-in-place, or "bore and jack," which allows the culvert to be installed while maintaining traffic with no road closures. Our water resources engineers provide hydraulic modeling with all culvert designs.

Historic preservation services include structural evaluation, repairs, renovations, or expansions to existing historic buildings and other structures across North Carolina. We work closely with architects and the North Carolina State Historic Preservation Office to provide the appropriate structural detailing necessary to maintain the historic character and integrity of the original construction.

A&O has many years of experience in structural design for pedestrian trails and sidewalks, including bridge and culvert design, boardwalks, and retaining walls. Because of our combined expertise in structural and water resources engineering, we can design structures with the hydraulics component in mind, developing the most cost-effective and practical solution for the client.

A&O has many years of experience designing retaining walls for NCDOT, municipalities, parks, greenways, and other public and private entities. Types of retaining walls have included cast-in-place concrete, segmental block, and timber. We have designed soldier pile walls, in which H-shaped steel piles are drilled deep into the earth at regular intervals. Soil nail walls stabilize soil by rods inserted and anchored into the soil. A gabion basket wall is made of rocks held in place by a metal cage similar to chain-link fencing. An MSE (mechanically stabilized earth) wall is made up of alternating layers of backfill and soil reinforcement fixed to a wall facing.

A&O provides visual, hands-on safety condition inspections of traffic signal structures for NCDOT. Using a bucket truck, we perform close-up inspections of tops of poles and mast arm connections to the vertical poles. We check anchor bolt nuts for tightness, damage and rust. We use an ultrasonic wall thickness gauge to check the material thickness of the pole and mast arm. The overall condition of the poles and mast arms are examined to determine if maintenance is required. We document the structural elements of each pole and provide a record for inventory by providing plan and elevation sketches.

A&O's repair designs for dams have included erosion repair and remediation of damage from roots of trees that have grown in an earthen dam. For concrete dams, we design repairs to cracks or spalls with cementitious sealers and shotcrete. Other improvements include replacement and repair designs for sluice gates, siphons, and trash racks. We may work with a diving contractor to collect field data and will coordinate approvals through the US Natural Resources Conservation Services, the North Carolina Dam Safety Program, and local entities.