SH-7 Roadway Design: Bridge and Approaches over Pecan Creek

Problem

Replace a deficient creek crossing on SH-7 without interrupting traffic, expanding the project footprint unnecessarily, or introducing construction-phase uncertainty that could drive change orders.

The existing structure required replacement to meet current design expectations. At the same time, the rural highway needed to remain operational, and the project had to avoid overbuilding beyond what conditions required. The tension was clear: deliver a compliant, durable crossing while tightly controlling scope and constructability.

Approach

Guernsey structured the project around constructability as the primary risk control.

The team replaced the existing structure with a reinforced concrete box (RCB), selected for its straightforward, repeatable construction process and reduced field variability compared to more complex structural systems. This choice simplified installation and limited the potential for unforeseen conditions to disrupt progress.

To maintain traffic throughout construction, Guernsey designed a shoo-fly detour alignment. This eliminated the need for complex staging or intermittent closures, reducing contractor coordination challenges and removing a common source of schedule pressure and field-driven design changes.

Rather than defaulting to full reconstruction, Guernsey applied a 3R/4R design approach. This allowed the team to selectively upgrade the corridor where necessary while retaining elements that did not require modification. By aligning improvements with actual need, the design avoided unnecessary expansion of scope and reduced exposure to cost and schedule variability during construction.

Roadway improvements were defined early using standard, compliant dimensions, including a 40-foot clear roadway with 12-foot lanes and 8-foot shoulders. Establishing these parameters upfront aligned the design with current criteria and minimized the likelihood of redesign during later project phases.

This approach avoided the need for complex staging, iterative redesign, and field-driven scope adjustments that commonly affect similar replacement projects.

This project demonstrates that constructability is not a downstream consideration. It is a design decision that determines whether a project proceeds as planned or is reshaped in the field. By controlling installation complexity, maintaining traffic through a defined detour, and limiting scope to necessary upgrades, Guernsey reduced the conditions that typically lead to change orders and construction delays.