OVERVIEW

"For years, DelDOT has demonstrated its commitment to implementing new and innovative bridge replacement techniques that decrease construction time, improve commuter and work zone safety, and minimize user costs.”

The Bridge 1-488N&S project involved the accelerated replacement of two structurally and hydraulically deficient bridges carrying US Route 13 over Blackbird Creek in northern Delaware — a four-lane divided highway with a projected AADT of 13,500 vehicles per direction by 2050. Both bridges, originally built in 1920 and 1933, suffered significant spalling, cracking, exposed bar corrosion, and scour issues. The Delaware Department of Transportation (DelDOT) opted for Accelerated Bridge Construction (ABC) techniques to replace both structures during a 45-day closure of US 13 — a timeline that would take approximately one year using conventional methods.

PRECAST SOLUTION

Precast Systems Inc. fabricated the full precast concrete component package for both bridge replacements. The new bridges are composed entirely of precast concrete elements, with the primary structural system utilizing 125-foot-long, 66-inch-deep decked bulb-tee beams with end diaphragms, supported on precast concrete stub abutments founded on prestressed concrete piles. Foamed glass aggregate (FGA) was used as backfill, and ultra-high-performance concrete (UHPC) closure pours transversely connect adjacent beams and approach slab segments.

Precast concrete abutments replaced the traditional cast-in-place approach — each section weighing approximately 40 tons, cast in two variable-height segments with a shiplap overlapping joint at center to accommodate a 2% cross slope. The reduced size and weight of the segmental abutments simplified transportation and placement significantly. Precast concrete approach slab segments and moment slabs complete the system, with UHPC closure pours connecting all adjacent precast elements.

Construction began with a full road closure of northbound US 13 on September 8, 2025, with both directions reopened to traffic within 45 days.

Content and photography from "Accelerated Bridge Construction of Two Bridges in Delaware" by Nicholas Dean, Delaware Department of Transportation. ASPIRE Magazine, Summer 2026, pp. 14–18.

See the full article here: Aspire Magazine • Summer 2026 • Page 14

Owner

Delaware Department of Transportation (DelDOT)

PCI-Certified Precast Producer

Precast Systems Inc.

Bridge Design Engineer

Delaware Department of Transportation (DelDOT)

General Contractor

Richard E. Pierson Construction Co. Inc.

Key Project Attributes

• Fully precast bridge system — decked bulb-tee beams, stub abutments, piles, approach slabs, moment slabs, and T-wall segments all in precast
• 45-day accelerated construction window — a comparable conventionally built replacement would require approximately one year
• Northbound US 13 reopened after 44 days; southbound reopened after 37 days of closure
• UHPC closure pours connecting all adjacent precast elements transversely — eliminating cast-in-place deck forming
• Foamed glass aggregate (FGA) backfill selected to accommodate tolerances and achieve proper pile spacing in challenging soil conditions
• Precast abutment sections cast in smaller segments (~40 tons each) to minimize transportation and placement challenges

Project/Precast Scope

• 16 × 66"-deep Decked Bulb-Tee Beams, 120 ft
• 32 Prestressed Piles
• 8 Abutment Segments
• 16 Approach Slab Segments
• 14 Moment Slabs
• 154 T-Wall Segments
• 4 Sleeper Slabs
• Construction Cost: $12.1 Million