Bulb Tee

The Full Picture

A bulb tee gets its name from its cross-section: a wide top flange that works with the deck, a slender web, and a thickened bottom flange that holds the prestressing strands. Casting it in a plant lets the producer tension the strands and control curing, which is why bulb tees can span farther than a conventionally reinforced beam of similar depth. They are a form of precast, prestressed concrete.

Bulb tees come in standardized depths, and bridge owners commonly specify shapes from the AASHTO/PCI family, with the depth in the shape name. Each state DOT also publishes its own standard sections, so the shape on the drawings controls. Precast girder units are built outside traffic areas and shipped to the site, which is why bridge schedules favor them.

For takeoff, the primary unit is each piece, with length in LF shown beside it because the producer's price is driven by length, strand pattern and shape. A concrete CY quantity can be computed from the cross-section area and length when it is needed for a cross-check, but suppliers quote per piece or per LF. Erection is a separate item: crane or launching equipment, falsework or bracing, bearing pads, diaphragms and the cast-in-place deck. Those are usually carried by different trades or line items.

The documents to read are the structural framing plan, the girder schedule and the beam details, plus the precast concrete specification section in Division 03. Look for camber, end-block details, lifting and sweep tolerances, and shipping limits. Piece weight and length matter because they limit hauling routes and crane capacity.

Pricing pitfalls include counting girders at the span length instead of the fabricated length, missing skewed ends or special strand layouts that change the price, forgetting escort or oversize haul costs, and leaving crane mobilization and temporary works out of the number. Because lead times are long, the estimate should also note when the precaster needs shop drawing approval.