The story of TYLin is really the legacy of our founder, engineering legend and namesake, Tung-Yen Lin. His pioneering research in pre-stressed concrete redefined an industry and launched a multinational, multidisciplinary engineering consulting firm that continues to grow and innovate on behalf of our valued clients. The following are highlights of our rich history.

Before 1950
T.Y. Lin

Tung-Yen Lin, known as “T.Y.,” is born on November 14, 1912, in Fuzhou, China.

T.Y. Lin joins the faculty at UC Berkeley in 1946 and begins his innovative research in pre-stressed concrete that leads to significant advancements and the firm’s early focus.

Bering Strait

In 1954, T.Y. Lin founds T.Y. Lin Associates in Los Angeles, which later became T.Y. Lin International.

In 1958, notable projects include a bridge across the Bering Strait, known as the Intercontinental Peace Bridge, and the 13-story, 1800 Pacific Building in San Francisco, one of the earliest structures to use post-tensioning to control lift slab deflection.

SF Skyline

The firm relocates to San Francisco, increasingly expands its specialty in pre-stressed concrete to broader consulting services with designs that include conventionally reinforced concrete, structural steel, masonry, and timber-framed structures.

In 1967, T.Y. Lin International completes the design of the Bank of America in Managua, Nicaragua, an 18-story shear wall office building. The reinforced concrete tower was one of two structures left standing after an earthquake shook downtown Managua in 1972.


International growth begins with T.Y. Lin International offices established in Taiwan and Singapore.

In 1973, T.Y. Lin International completes the Rio Higuamo Bridge in the Dominican Republic, the first pre-stressed, concrete segmental long-span bridge constructed in the Western Hemisphere.

Dar group logo

The firm continues to grow with new offices in Kuala Lumpur, Malaysia, and a merger with Maine-based Hunter-Bellow Associates.

In 1982, T.Y. Lin International designs the Moscone Convention Center in San Francisco, using long-span bridge technology for the 250,000-square-foot, column-free grand exhibit hall.

In 1986, T.Y. Lin receives the National Medal of Science from President Ronald Reagan.

In 1989, T.Y. Lin International Group is acquired by Dar Group, an international network of professional service firms, comprised of over 17,000 professionals with clients in over 100 countries.

Dr. Man-Chung Tang

T.Y. Lin International expands into new markets with the acquisition of California-based McDaniel Engineering, Chicago-based BASCOR, Washington’s DGES Consulting Engineering, and New York’s DRC Consultants. Our presence in Asia Pacific expands with the opening of an office in Chongqing, China.

In 1990, following the Loma Prieta earthquake in California, T.Y. Lin International plays a central role in the development of new and advanced techniques, engineering tools, and design standards for bridge assessment, seismic retrofit of existing structures, and the design of new bridges.

In 1995, Dr. Man-Chung Tang becomes Chairman of the Board of T.Y. Lin International.

In 1998, T.Y. Lin International begins work on the San Francisco-Oakland Bay Bridge. The single-tower, Self-Anchored Suspension (SAS) design is selected for the new Eastern Span of the San Francisco-Oakland Bay Bridge.

South Terminal Expansion at Miami International Airport

Growth continues with acquisitions of Miami-based H.J. Ross Associates, Inc., Northern California’s CCS Planning and Engineering, FRA Engineering and Architecture, and Medina Consultants, bolstering service offerings across markets, including ITS/traffic engineering, airports, rail and transit, water resources, and more.

In 2007, T.Y. Lin International completed engineering design and construction phase services for the $360 million South Terminal Expansion Program at Miami International Airport. The firm was also the engineer-of-record for landside roadways adjacent to the South Terminal facility.

Also in 2007, the New Benicia-Martinez Bridge opens to traffic, designed by T.Y. Lin International and constructed using the cast-in-place balanced cantilever method. The largest lightweight concrete segmental bridge in California, the superstructure has spans up to 659 feet.

T.Y. Lin International was also selected to provide ongoing flood insurance studies and flood insurance rate maps in support of FEMA’s Map Modernization Program.


T.Y. Lin International grows its position as a global leader in the design and construction of largescale infrastructure projects around the world, including record-breaking signature bridges, major airport expansions, and new transit systems across the Americas and Asia Pacific.

In 2010, designed by T.Y. International, the historic Hoover Dam Bypass Bridge opens to traffic.

In 2013, California's largest public works project to date, the new San Francisco-Oakland Bay Bridge opens to traffic, with T.Y. Lin International as Engineer of Record. The Chicago Transit Authority’s reconstructed Dan Ryan Red Line opens to riders. T.Y. Lin International served as Project Design Oversight Lead and Designer of Record on the project.

In 2015, T.Y. Lin International acquires South Carolina-based Lindbergh & Associates, strengthening and diversifying its markets across the Southeast United States and building a strong Federal services program.

In 2016, T.Y. Lin International acquires majority interest in IDEAM S.A. in Madrid, Spain, a premier structural engineering consultancy specializing in major bridges and complex structures throughout Europe, Latin America, and the Middle East.

In 2019, representing one of the most high-profile infrastructure projects in North America, the Samuel De Champlain Bridge over the St. Lawrence River in Montréal, Québec, Canada, opens to traffic. T.Y. Lin International served as Managing Partner and Lead Designer for the project.

Also in 2019, T.Y. Lin International acquires The Municipal Infrastructure Group Ltd. in Toronto, Ontario, Canada, a civil engineering consulting practice in the water, land development, and transportation sectors, establishing its first location in Canada.

TYLin Logo

Complimenting the firm’s building practice, New York based Silman joins T.Y. Lin International (2021).

In 2020, The 10-mile Bay Area Rapid Transit (BART) extension from Fremont to northern San Jose in California opens to users. T.Y. Lin International provided engineering design services for the historic project, which fulfills a decades-long plan of linking South Bay communities with BART and advancing public transportation use in the region.

In 2022, T.Y. Lin International rebrands as TYLin, the engineering consulting firm that connects people, places, and ideas.

In 2023, TYLin's parent company, Dar Group, becomes Sidara, a collaborative of specialist firms dedicated to elevating the human experience, advancing sustainability, and igniting transformation through innovation.

In 2024, GPO Group, IDEAM, and Tunnelconsult formally became TYLin Europe / Latin America providing planning, design, construction management, and operation services in the mobility and transportation industries.