The crossing that has to carry a fire truck.
Steel girders on driven pipe piles with a concrete deck, timber on timber piles where a ranch drive is all it will ever carry, and decked crossings on steel wingwalls where the creek does not need a bridge at all. The same crew, the same rig, and a load rating agreed before anything is drawn.
Every bridge is a commercial job.
Even the one on a ranch.
A property owners' association putting a road across the creek at the subdivision entrance. A county replacing a low-water crossing that closes the road every spring. A developer who needs the back forty reachable by a concrete truck before a single lot sells. A ranch whose only way to the far pasture is under water two months of the year. The first three are commercial clients by definition. The fourth is a private owner, and the bridge is still a commercial job — the same driven piles, the same girders, the same load rating, and the same crew that built the county's. There is no lighter version of a bridge that a fire truck can cross.
That is why bridges sit under the Commercial side of this site rather than the residential one, and why the page below spends its time on how the structure actually goes together. The people who buy bridges want to see the work.
How a steel bridge goes together.
Six operations, in an order that does not change.
Piles first. Steel pipe piles are driven at each abutment to refusal or to the depth the soil report calls for — the number and spacing set by the load rating, not by the span alone. Once every pile is in, they are cut to a single elevation, and that cut is the most important line on the job: the whole bridge sits on it.
Then the landing beam. A steel beam is fitted across the pile tops at each end and welded to every pile. It turns a row of individual piles into one bearing, and it is what the main girders land on. Dave regards fabricating and setting it as the step that decides whether the deck comes out true.
Then the girders, the deck, and the walls. The main I-beams are lifted one at a time and set on the landing beams; cap plates are welded out underneath; the concrete deck is formed and poured across the top and finished with curbs or a rail. Galvanized steel sheet-pile buttress walls hold the bank at each end so the approach cannot wash out from behind the abutment.
The build, from the first pile to the poured deck.
A steel bridge with a concrete cap and timber curbs on Houston County Lake, photographed as it went up.
The day the girders land.
One beam at a time, off a crane or an excavator, onto a landing beam that was welded true the week before.
Three minutes of it, on our own channel: the girders rigged, lifted and set one after another onto the landing beams. Nothing from YouTube loads until you press play.
Steel bridge — setting the girders
Dave's own footage from the Houston County bridge: each I-beam rigged, swung out over the creek and landed on the welded landing beam, the crew walking it into position on the sheet-pile buttress wall at either end.
Carrying traffic over moving water.
A county road bridge: steel girders, a concrete deck and parapet, a steel guardrail, and riprap holding the bank under the abutment.
Where timber still makes sense.
A ranch drive, a park access road, an island crossing: where the heaviest thing on the bridge is a pickup, a stock trailer or a tractor, timber on driven timber piles is the right buy. Solid sawn stringers run out around 26 feet of clear span; past that it is glulam or an intermediate pile bent that turns one long span into two short ones. This one, in Montgomery County, was decked and railed with the excavator still on site.
Timber bridges get their own page — span limits, load ratings, treated timber and hardware, scour at the abutments, and the permits a creek crossing raises — at Timber Bridges. Where the creek is short and the water is not, a decked crossing on steel wingwalls is often the better answer than a bridge of any kind, and we will say so.
What gets decided before a pile is driven.
The load rating. For anything vehicles use, HS-20 is the common benchmark: 72,000 pounds on three axles. HL-93 is the modern AASHTO model, a design truck or tandem plus a lane load. A county or state project specifies it; on a POA or private bridge we agree it with you first, because it sets the pile count, the girder section and most of the price. The number to design for is the heaviest vehicle that will ever need to cross, not the one that crosses most.
The permit. Usually the question is not the bridge but the fill. Section 404 of the Clean Water Act covers placing dredged or fill material in waters of the United States, which is what abutments, approaches and riprap are. A pile-supported span that keeps its footprint out of the channel often stays inside a nationwide permit; a crossing that fills the creek bed usually does not. We sort out which applies before design, not after.
The public client. When the owner is a county or a state agency, the structure is the same and everything around it is heavier — permitting, insurance requirements, inspection and as-built documentation. It adds time and cost to the same span, and it is part of why public work carries a different number from a private bridge. It is also why an agency that has been burned by a low bid tends to ask how many bridges a contractor has actually driven piles for. Ours are above.
Bridge FAQ.
Is a bridge a residential or a commercial job?
Commercial, almost without exception. A property owners' association, a subdivision developer, a county or a state agency is a commercial client by definition, and a private bridge on a ranch is built to the same standard, with the same equipment and the same load rating, so it is priced and managed as commercial work too. That is why bridges live under the Commercial side of this site.
What kind of bridges does Shoretech build?
Steel girder bridges with a concrete deck on driven pipe piles, for county roads, subdivision entrances and shared drives that have to carry fire apparatus and delivery trucks. Timber bridges on driven timber piles for ranch drives, park access and island crossings. And short decked crossings carried on steel sheet-pile wingwalls where a full bridge is more than the creek needs.
How is a steel and concrete bridge built?
Steel pipe piles are driven at each abutment, then cut to a common elevation. A steel landing beam is fitted across the pile tops and welded to each one. The main girders are lifted and set on the landing beams, cap plates are welded out, and the concrete deck is formed and poured on top with curbs or rails to finish. Galvanized steel sheet-pile buttress walls hold the bank at each end.
What load should a bridge be designed for?
For anything vehicles use, HS-20 is the common benchmark: 72,000 pounds on three axles. HL-93 is the modern AASHTO model that pairs a design truck or tandem with a lane load. A county or state project will specify the rating; for a private or POA bridge we agree it with you before design, and it drives the pile count, the girder size and the price.
What changes when the client is a county or the state?
The structure is the same. What changes is everything around it: the permitting is heavier, the insurance requirements are higher, and the documentation runs to inspection reports and as-builts a private owner never asks for. It adds time and cost, and it is part of why public work is priced differently from a private bridge of the same span.
Related services.
Have a creek that needs a road over it?
Four things get a useful first answer: how wide the crossing is, the heaviest vehicle that has to use it, what the water does in a big rain, and who the owner is — a county, a POA, a developer or you. Based in Trinity, we travel as far as the job needs.