September 29, 2026
The Team Behind the Interchanges: H&S’s Transportation & Structural Bench, Now Backing Utah
H&S’s Transportation Engineering and Structural Engineering groups have spent decades building and rebuilding some of the St. Louis region’s busiest interchanges, and the results are the kind you can pick out from an airplane window. With H&S’s acquisition of O’Neill & Company and the opening of a Salt Lake City office, that same bench now stands behind an established Utah team and its long-standing local client relationships. Conversations about roundabout geometrics, safety improvements, drainage plans, and bridges over interstate highways are coming up more often in the West — and the engineers on the other end of their design and conception have already delivered that work at scale for three state DOTs, county and municipal agencies, and local public agency programs.
Roundabouts, Interchanges, and Constrained Sites
Jon Loos, PE, Regional Manager for Transportation Infrastructure Engineering, has been designing and managing that work since 2011, when he joined as an intern. He came on full-time the following spring, after H&S won the I-70 Outer Roads project in St. Charles County. In that time, he has participated in four of Horner & Shifrin’s Design-Build projects and was the roadway design lead for the Lindbergh Boulevard interchange on MoDOT’s I-270 North Design-Build, one of the largest design-build programs MoDOT has delivered in the St. Louis District. On this award-winning project (APWA National Transportation Project of the Year), roadway design had to stay coordinated with the bridge and drainage work advancing on the same corridor. Loos also served as Design Lead and Project Manager on the Little Hills Expressway/Mel Wetter Parkway Roundabout in St. Charles, a 2023 Missouri APWA Project of the Year.
Little Hills was a challenging roundabout site because the existing grade did not naturally support the geometry the intersection required. To design for appropriate entry angles, vehicle speeds, and sight distance, the team reshaped the site while still controlling drainage and accounting for poor subgrade conditions. Those constraints ultimately impacted several major design features, including a retaining wall, targeted subgrade remediation, and open drainage with rock-lined ditches.
“Every problem has a solution. Sometimes it just takes thinking outside the box to find it. Having the opportunity to make key design decisions, even early in my career, accelerated my development as an engineer and gave me the confidence I have today when serving clients,” Loos says.
Safety Work With Numbers Behind It
Dave Riechmann, PE, Regional Manager for Transportation Infrastructure Engineering, brings the roadway safety side of that same bench. Riechmann served as Roadway Lead on both of MoDOT’s Safety Design-Build projects for the St. Louis District, which together implemented more than 500 safety countermeasures at over 260 locations across St. Charles, Franklin, St. Louis City, and St. Louis County. An independent before-and-after study found Safety Design-Build 1.0 prevented 87 fatal and serious injury crashes and saved 44 lives over ten years, more than three times the original projection, while coming in under budget. Riechmann is now part of a team designing a Strategic Highway Safety project for St. Charles County that applies the same data-driven countermeasure approach across 11 additional roadway segments.
What makes that kind of program repeatable is where it starts. The work begins with crash data rather than a corridor wish list: locations are screened and ranked by crash type and severity, then matched to countermeasures with documented effectiveness, so the dollars land where the crash history says they will do the most good. Spreading a fixed budget across more than 260 locations instead of concentrating it on a handful of corridors is a deliberate choice that approach makes possible, and the independent before-and-after study is what separates it from a program that simply reports what it built.
Riechmann’s background also includes hydraulic analysis, stormwater drainage, and water quality design across more than a dozen resurfacing and drainage-driven roadway projects in the St. Louis metro area.
Bridges, Culverts, and the Conditions Around Them
Carrie Beth Collier, PE, Assistant Regional Manager for Structural Engineering, oversees MoDOT, IDOT, and other bridge and drainage-related structural work across the region. On MoDOT’s I-270 North Design-Build, the same project where Loos led roadway design at Lindbergh Boulevard and Riechmann led drainage design, Collier served as Lead Bridge Designer and Hydraulic Engineer for the structures over Coldwater Creek. Her projects sit at the proverbial intersection of the interchange and roadway work Loos and Riechmann lead and the drainage and hydraulic analysis that keeps those corridors functioning through harsh Midwestern weather.
Structures over a creek are as much a hydraulics problem as a bridge problem. Span arrangement, pier placement, and low-chord elevation all get set against how much water the drainage area delivers in a design storm and how much backwater the crossing can create upstream, and the scour protection follows from the same analysis. Carrying both the bridge design and the hydraulic engineering on a crossing like Coldwater Creek keeps those decisions in one place instead of handing them back and forth. It is also why the structural group and the transportation group at H&S tend to show up on the same projects.
“I have spent a great deal of my career designing bridges, and I love structural design and analysis, but I started doing a lot of overland hydrology and bridge hydraulic analysis for Horner & Shifrin about 14 years ago,” Collier says. “I have worked with several engineers in our Transportation Infrastructure Engineering and Structural Engineering groups for more than 19 years and we work seamlessly together on these types of projects, which becomes an asset to our clients. We know and understand what the requirements are for this type of work, and we know how to work well together as a team at Horner & Shifrin.”
Not all of that structural work is driven by water. On MoDOT’s Broadway over I-44 project in downtown St. Louis, H&S led the design team that replaced the two deteriorating, heavily skewed bridges carrying Broadway over the interstate (a single-span steel girder structure over westbound I-44 and a two-span prestressed concrete structure over eastbound I-44) on a route carried on the Governor’s Focus on Bridges list.
The constraints there were urban rather than hydraulic. Collier and the design team had to raise vertical clearance, shorten the span over I-44, and reduce a skew that still finished near 60 degrees (which drove a decision to use semi-integral abutments) while improving sight distance at the express lanes ramp and leaving the adjacent I-44 ramps and the new Cass Avenue bridge untouched. Existing abutments were reused as retaining walls to hold down cost, the decommissioned express lanes bridge was replaced with MSE wall-supported fill over stone column ground improvements in poor soil, and maintenance of traffic had to work in a tight downtown footprint that included closing more than six miles of the I-70 express lanes. That is the same problem set a grade-separated crossing presents in a built-up Salt Lake City corridor: constrained geometry, utilities with nowhere to relocate, and traffic that cannot simply be detoured.
Why The Experience Travels
Utah is a new market for the St. Louis bench, but the underlying work isn’t new to this team. UDOT has long been one of the country’s most experienced design-build and safety-focused owners, and the work this team has delivered for MoDOT follows the same model: data-driven countermeasure selection, integrated design-build delivery, and corridor-scale programs. Roundabout geometrics, complex interchange design, hydraulic and stormwater analysis, and data-driven roadway safety are exactly the capabilities UDOT and Utah’s AEC community are evaluating for their own priority corridors, and they are capabilities H&S has already delivered across Missouri, Illinois, and Arkansas, including award-winning, independently verified results for MoDOT.
The specifics change from state to state, and some of them change a great deal: design manuals, standard drawings, and review processes are local, and so are design conditions like seismic demand and snowmelt hydrology that Utah corridors carry and Missouri corridors do not. Pairing the O’Neill team’s familiarity with those conditions with the St. Louis bench’s design-build depth is how the combined group covers both. What does not change is the shape of the underlying problems. A priority interchange in Utah still has to reconcile geometry with grade, drainage, and structures; a safety program still has to defend its countermeasure selection against crash data; a bridge over a channel still has to satisfy the hydraulics before it satisfies anything else. That is the part of the work this team has already done repeatedly, at scale, for three state DOTs — MoDOT, IDOT, and ArDOT — and a long list of county, municipal, and local public agency clients.
One Firm, Not One Office
That is what the Salt Lake City office opens with. H&S staffs pursuits and projects as one firm rather than one office, so the new Utah presence isn’t building a transportation and structural practice from scratch. The O’Neill & Company team brings the local relationships, agency familiarity, and Utah project history; the St. Louis bench brings decades of design-build roadway and bridge delivery. Neither side is starting over. Loos, Riechmann, and Collier are available to Utah clients in the same roles they hold in St. Louis: project management, roadway and safety lead, bridge design, and hydraulics — whether that means leading a pursuit, backstopping the local team, or running QC/QA on a corridor study.
Utah agencies and teaming partners interested in learning more about H&S’s Transportation Infrastructure Engineering and Structural Engineering capabilities in the West Region can contact the H&S West Region team.