The Texas Department of Transportation's (TxDOT) $53.2 million demolition, reconstruction and extension of the Interstate 69 bridge over the Brazos River in Sugar Land is nearly 60 percent complete.

The project, which started on June 22, 2024, is expected to be delivered by SER Construction Partners LLC in November 2027.

SER Construction photo

The three-phase initiative moves the end of an existing bridge further inland to avoid damage from an eroding riverbank. Phase 1 was completed last summer. Phase 2, which ran from June 2025 to March 2026, dealt with the southbound I-69 main line bridge and the inside lanes.

Phase 3 began in March 2025. This work includes the construction of the northbound main lines and a northbound frontage road that should be completed by March 2027.

A changing Brazos River is the project's root cause.

The erosion of the riverbanks in the Fort Bend County area resulted from heavy storms in 2015 and 2016, followed by Hurricane Harvey in 2017. In 2023, the city and county received $70 million for erosion control projects.

"Due to the expected migration of the Brazos River, TxDOT is extending the bridge by approximately 700 feet to the north," SER Senior Project Manager Ben Cross told Construction Equipment Guide.

The scope of the project is immense.

It requires the demolition of three existing bridge spans — approximately 300 linear feet, 10-lane concrete pier and beam structures — as well as the demolition and reconstruction of 10 lanes of concrete I-69 main lanes (700 ft.) and two lanes of frontage road (1,000 linear ft.) northbound and southbound.

The new 1,000-ft., 10-span, 10-lane pier and beam bridge is expected to be completed in winter 2027.

Crews also are removing a damaged turnaround beneath the bridge and placing armoring on the bridge's northern foundation to prevent additional erosion damage.

"The erosion under the bridge has gotten out of hand," Kristina Hadley, a TxDOT spokesperson, told the local media. "We just need to repair it and try to stop this erosion."

The project was designed by LJA & Associates.

SER Construction photo

So far, SER has completed the entire southbound side of the main lane bridge and southbound frontage road bridges. Work over the next 18 months will focus on the northbound half of the main lane bridge, as well as the northbound frontage road.

Cross and his team are dealing with multiple challenges, although soil and utility issues are minimal.

"The greatest challenge has been the traffic volume of the roadway," he said. "At the time of bid, it was estimated that the main lanes and the frontage roads of I-69, within the project limits, experienced more than 180,000 vehicles of average daily traffic. TxDOT and the designers worked to minimize the amount of lane reductions and maintain five lanes of traffic each way, while allowing adequate work room to construct the bridge.

"Additionally, the Brazos River has been unpredictable. After significant rains, it will rise quickly. A couple of times, it has flooded the work zone under the bridge. We have to be on alert to rising water levels."

Cross said the project remains on schedule, with crews primarily working during the day, six days a week. Crews have worked night shifts on occasion to perform tasks requiring lane closures, major traffic switches, beam erection and concrete deck pours.

Crews are operating in a tight work zone, Cross said.

"While constructing the interior lanes of the main lane bridge, we are working with traffic on both sides of the work zone," he said, "which makes access very difficult."

The existing bridge is being partially demolished.

SER Construction photo

"It is traditional hydraulic hammer demolition using large excavators," Cross said. "The biggest challenge is to avoid damaging the portions of the existing bridge that are to remain and doing the demo work in tight spaces. We are demolishing the beams and deck up to the existing Bent No. 7, which is to remain in place and support the new bridge, so we had to be extremely careful while demolishing the beams at this bent to not damage the bent cap. So far, we have been very successful and have not had any damage."

This is a phased demolition and reconstruction process.

"We are constructing the main lane bridge in four steps to allow traffic to use both the existing bridge and newly completed bridge sections," Cross said. "The bridge construction is exclusively north of the river; however, we are removing and replacing a concrete rail over the river to bring the rail up to the latest MASH compliance. We are not using any false work but are very careful to avoid any debris falling into the river."

"Along with the bridge construction, which is a very typical pier and beam construction, we are also installing a sheet pile wall around the foundation of the existing Bent 7 substructure," he added. "The state expects the Brazos River to migrate north and significantly erode/scour the foundation of this bent. We are driving steel sheet piling around the entire foundation substructure (the battered piles and footings) to achieve bearing and protect this bent from erosion."

Demolition debris is being hauled off via trailers.

Cranes on site include a SANY Scc8100 110-ton crane, a Manitowoc 11000-1 110-ton crane and an 80-ton hydraulic crane. Other pieces of iron consist of a 30-ton cherry picker, Cat 349 excavators, Cat 926 loaders, Cat D3 dozers, a GOMACO 2600 slip form paving machine (roadway) and a Bidwell 5400 concrete bridge deck paving machine. Additionally, a subcontractor rented a Liebherr LTM 1400-7.1 500-ton hydraulic crane.

SER Construction photo

Crews are constructing one side of the bridge at a time.

"Each phase follows the following sequence — a traffic shift to generate the work zone, demolish existing bridge and roadway, install drilled shaft foundations, erect columns and bents, erect beams, set precast deck panels, and pour the bridge deck," said Cross, who noted that there are approximately 200 48-in. diameter drilled shaft foundations for the main lanes that are around 65 ft. deep.

SER is using precast concrete beams, deck panels and reinforced concrete pipe, manholes and inlets for the bridge and, for the roadway surface and subgrade, concrete, cement-treated base and lime.

Whether one is demolishing or constructing a bridge, a comprehensive safety program is essential, Cross said.

"Our safety plan details the work plan, including access to the site, the equipment being used, designates a competent person and has emergency response protocols," Cross said.

The demolished main line lanes and frontage roads just north of State Highway 99 in Sugar Land are being reconstructed.

"Each of the four phases of the project encompasses about three lanes of pavement that were taken out simultaneously from one end of the bridge to the other, depending on access," Cross said. "The bridge/roadway is demolished in place, and the concrete and steel are processed (crushed) on site and then loaded directly onto trailers and hauled off site. The storm sewer system at the river is being completely reconstructed."

Subcontractor Martin Marrietta is performing the demolition work, using large KOBELCO excavators with buckets and hydraulic hammers.

SER Construction photo

The new concrete lanes feature a lime subgrade, a cement-stabilized base, an asphalt bond breaker and a concrete surface.

"We're completely reconstructing the two northbound and southbound frontage road lanes for about 1,000 ft. on the north side of the bridge," Cross said.

Cemex is supplying SER with ready-mix concrete.

Project Manager Jonathan Martinez, Project Superintendent Jose Lara and Traffic Superintendent Jose Quintanilla assist Cross.

Typical days have 20 to 30 SER and subcontractor employees on site. The major subcontractors are Martin Marietta, Stripe Lines (traffic control and striping), Traffic Control Devices (lighting and fiber optic work), Tom Mac (sheet pile driving), HB Farmer (drill shaft foundations), Roadway Construction (soil nail walls), Scott Derr (painting), Semark (landscaping) and Willow City (signs and metal beam guard fence).

Demolition and excavation operations have generated 37,874 sq. ft. of concrete paving, 7,000 sq. yds. of bridge deck and 230,000 cu. yds. of various materials.

"The crushed concrete will most likely be recycled," Cross said. "The excavated soil will be sent to a dump."

New materials include 3.2 million lbs. of reinforcing steel, 28,300 cu. yds. of concrete, and 36,000 linear ft. of concrete bridge girders.

SER's fleet, including a variety of Cat equipment, is well maintained.

"We have a staff of mechanics that travel to each project as needed," Cross said.

SER buys and rents its Cat equipment from the Houston area's Mustang CAT. CEG

(All photos courtesy of SER Construction.)