The professional engineering firm of Louis T. Klauder and Associates was founded in Philadelphia in March 1921 by Louis Tobias Klauder (1880-1945), who remained proprietor until his death. He was succeeded by his son Louis Thornton Klauder (1907-1999) as managing partner from April 1945 to December 1984. The firm came to specialize in the design and evaluation of railroad and rail transit systems, including equipment, infrastructure and operations, as such it is now (2014) the only U.S. consulting firm specializing in rail systems, and is employed by numerous passenger rail and rail rapid transit operators. Although still a partnership Louis T. Klauder and Associates registered the "doing business as" name of LTK Engineering Services on November 21, 1994. It has relocated its headquarters from Center City Philadelphia to suburban Ambler and maintains several branch officers around the country. As the leading railroad engineering consultancy, Klauder was a natural choice for the federal government's earliest attempts to implement high speed rail service in the 1960s and 1970s.

The Northeast Corridor Demonstration Project began as a reaction to Japan's first "bullet trains," the 1964 New Tokaido Line between Tokyo and Osaka, and from an initiative of Sen. Claiborne Pell of Rhode Island to improve ground transportation in the Boston-Washington population corridor. President Johnson included a high speed rail line in his "Great Society" state of the union message in January 1965, and on September 30 he signed the High Speed Ground Transportation Research and Development Act, with an initial appropriation of $90 million and a goal of 160 miles per hour. The act created the Office of High Speed Ground Transportation in the Department of Commerce (DOC), later moved to the Department of Transportation (DOT) when that department was created in 1967, and still later subsumed in the Federal Railroad Administration (FRA). Louis T. Klauder & Associates were engaged as consulting engineers to prepare estimates, develop specifications, secure bids from contractors, and then oversee implementation of the project as intermediaries between the participating companies (the railroads and equipment manufacturers) and the government administrators. The government staff devoted more of their time to evaluating more exotic technologies, such as magnetic levitation (maglev) vehicles and linear induction motors. Klauder also helped the USDOT develop the High Speed Ground Test Center's test track near Pueblo, Colo., on which a variety of rail or tracked vehicles could be tested.

The Department of Commerce ordered a set of four test cars from the Budd Company, basically electric commuter car shells modified for high speed running and packed with test instruments. The Pennsylvania Railroad spent additional sums to improve the track, catenary wire, signals and infrastructure for high-speed running. Two tracks of the four-track main line between COUNTY Interlocking south of New Brunswick and MILLHAM Interlocking north of Trenton, a straightaway through sparsely populated territory, were designated as the test tracks. The main focus was on the New York-Washington half of the Northeast Corridor, where the PRR main was completely electrified, had long straight sections, and was already equipped for fast running. The New York-Boston half was then owned by the bankrupt New York, New Haven & Hartford Railroad Company (NH), was only electrified as far east as New Haven, and had long sections of winding track along the shore of Long Island Sound. The NH became the site for a second, lesser demonstration project with a low-center-of-gravity gas turbine train, the TurboTrain of United Aircraft Corporation, that was equipped with tilting devices to permit it to take curves at higher speeds. The Northeast Corridor Demonstration Project was to become a textbook example of how not to do things. Unlike high speed rail projects in other countries, which start with entirely new rights of way, the U.S. planned to run high speed passenger trains on existing tracks, whose alignments often dated from the mid-19th century, and which were also used by much slower freight trains and conventional intercity and commuter trains. As speeds increase above 90-100 MPH, a host of issues become ever more critical, including aerodynamic drag, stresses on the rails, trucks and suspension systems, the mounting of the traction motors that power the wheels, braking, maintaining contact between the roof-mounted pantographs and the overhead catenary wire that provides the power, and maintaining sufficient voltage to the cars. U.S. railroads and equipment builders had mastered the art during the first phases of high speed running between the 1890s and 1930s, but as events were to show, had fallen badly behind. Indeed today, high speed passenger rail is almost entirely the domain of foreign firms. The mechanical and electrical systems required for sustained high speed operation proved almost insurmountable obstacles, a learning curve not unlike that in the U.S. space program in the 1950s and very early 1960s.

It did not help that the project was rushed to meet political and public relations-inspired deadlines or that struggling railroads and passenger car builders were desperate for government R&D funding and good press. The four DOC test cars were delivered by Budd and the propulsion contractor, General Electric, and began road testing in the fall of 1966, but experienced numerous problems at speeds over 80 MPH. The instrumentation contractor, Melpar, Inc., was relieved because of tangential connections to the Bobby Baker influence-peddling scandal. Eventually, the test cars were coaxed up to 155 MPH, which was the target for government acceptance, on April 2, 1967.

However, the 50 prototype cars, eventually dubbed Metroliners, were ordered before the test cars had been debugged, with the stated goal of beginning high speed service in October 1967. The Budd Company made the winning bid, with the electrical work shared between General Electric and Westinghouse. The Commonwealth of Pennsylvania, through the commuter agency SEPTA, ordered an additional 11 cars for a projected Philadelphia-Harrisburg service. As it turned out, most of the work and Budd's in particular, failed to meet the performance specifications, with over 100 specific shortcomings. SEPTA refused to accept its cars, and leased them to become part of the Metroliner pool.

Eventually, six Metroliner cars were considered acceptable to begin regular revenue service with one train each way in early January 1969. A reasonably full service was not achieved until mid-1971. Even so, there were numerous equipment failures, and the trains had to carry teams of technicians to monitor their performance and intervene in case of emergencies. The trains never achieved their goal of 160 MPH, rarely running over 125 MPH, and even having their speeds cut to close to conventional train speeds in their first years. However, their new look and airline-style amenities did lead to a resurgence of rail passenger travel in the Corridor that has continued.

Before the Metroliners could be put in sufficient shape for revenue service, the Pennsylvania Railroad Company had merged with the New York Central (February 1, 1968) to form the Penn Central Transportation Company, then absorbed the New Haven at the end of the year, giving it ownership of the entire Northeast Corridor. Penn Central in turn collapsed in bankruptcy in June 1970. On May 1, 1971, the National Railroad Passenger Corporation (Amtrak) assumed the operation of most intercity passenger trains, including the Metroliners, and it assumed full ownership of the Northeast Corridor in 1976.

At the end of 1971, Robert B. Watson, who had been the Penn Central's coordinator on the Northeast Corridor Project left the bankrupt company and joined the Klauder staff, taking with him personal copies of many of his files from the railroad's side of the project. Watson continued to work with the never-fully-debugged Metroliner cars, as well as other commuter rail and high-speed rail projects across the U.S. and in Korea, becoming LTK's Project Manager for all work for the Federal Railroad Administration. This included working on an upgrade of some of the Metroliners that improved their performance at the cost of reducing their maximum speed. The test cars remained the property of the federal government and were later used as instrumentation beds in a variety of tests around the country. One of Klauder's other assignments was to develop the concept of what became Auto-Train. Vacationers would drive to a central spot in the Virginia suburbs of Washington, where their autos would be placed in special railroad cars and carried overnight to Jacksonville, Florida, from which they would disperse to scattered Florida destinations the next day. The original concept called for people to remain in their automobiles, leaving only to use bathrooms and visit lounge and dining cars. When Auto-Train was implemented by a private company, they used second-hand standard auto carriers and conventional passenger cars, which achieved a more efficient packing of automobiles and a better ride for passengers. The construction of Walt Disney World and the location of the principal resorts on both coasts dictated placing the Florida hub at Orlando instead of Jacksonville.

LTK's involvement in the Northeast Corridor tapered off during the 1980s. By then, the original Metroliners had been bumped from their Northeast Corridor runs by locomotives of Swedish design hauling cars that are really unpowered Metroliner shells. These were superseded in turn by the next-generation Acela, combined with billions in government-funded infrastructure improvements. The Metroliners were first downgraded to Philadelphia-Harrisburg service, and then either converted to cab control cars for push-pull service on regular trains or scrapped. The Auto-Train service was popular enough that it was later assumed by Amtrak after the private operator failed.