LTV's (Vought) Airtrans was an automated people mover system that operated at Dallas Fort Worth International Airport between 1974 and 2005. The adaptable people mover was utilized for several separate systems: the Airport Train, Employee Train, American Airlines TrAAin and utility service. All systems utilized the same guideways and vehicle base but served different stations to create various routes.
After 30 years of service the system's 1970s technology was no longer adequate for the expanding airport's needs, and in 2005 it was replaced by the current Skylink system. While most of the system was auctioned and sold for scrap, some guideways and stations (some of which are still open to the public) remain. Airtrans moved nearly 5 million people in its first year of operation; by the end of its life it had served over 250 million passengers.The demonstration of automated guideway transit for accelerated urban deployment. by LTV Corporation. 1975
Airtrans technology was expected to be deployed in similar mass transit systems around the US. In Japan, the system was licensed by a consortium formed between Niigata Engineering and Sumitomo Corporation for similar deployments there.AGT 1975, pg. 47 Niigata Engineering has since supplied this technology for urban people mover systems such as Osaka's Nankō Port Town Line, Hiroshima's Astram Line and Tokyo's Yurikamome.
History Background During the early 1960s there was growing concern in the United States about the effects of urban sprawl and the resulting urban decay that followed. Major cities across the country were watching their downtown cores turn into ghost towns as the suburbs expanded and caused a flight of capital out of the cities. The only cities that were combatting this were the ones with effective mass transit systems; cities like New York City and Boston, where the utility of the subway was greater than a car. However, these solutions were extremely expensive to develop, well beyond the budgets of smaller cities or the suburbs of larger ones. Through the 1960s there was a growing movement in urban planning circles that the solution was the personal rapid transit (PRT) system, small automated vehicles that were much less expensive to develop.
At the same time, as Project Apollo wound down and President Richard Nixon started disengaging from the Vietnam War, there was considerable concern in the aerospace industry that the 1970s and 1980s would be lean times. The highly automated operation the PRT systems required, along with the project management needed to build a large mass transit system, was a natural fit for the aerospace companies, and by the late 1970s many were working on PRT systems. In 1970 LTV joined these efforts, when the Vice President of Engineering formed a study team to investigate ground transportation systems. They sketched out a system using off-the-shelf hardware to build a new PRT design.Vought, Program Background
DFW bid
The Dallas Fort Worth International Airport had recently started construction, and a people mover was one of their requirements. The airport consisted of four semi-circular terminal areas arranged in a line with large parking lots on either ends of the line, and two hotel towers in the middle. It was miles from one end to the other, so some form of rapid transit was needed to move people around the complex. DFW wanted the system to transport not only people, but mail, trash, supplies, and baggage as well. Varo Corp. had recently purchased the Monocab concept from its private developer and were pitching the system to DFW. LTV was asked to join them in a joint proposal, which was submitted late in 1970, along with two others from different providers. However, all three were over the price the airport had budgeted, and the companies were asked to re-submit.
Varo declined, and sold their interest in Monocab to Rohr, Inc., which later re-emerged as the Rohr ROMAG. LTV decided to submit their original design for the May 1971 deadline, developing their guideway to match existing highway specifications and construction techniques as a way to lower costs. Since they had no time to develop prototype hardware, they instead backed up their proposal with an extensive computer simulation of full operations. Westinghouse and Dashaveyor (Bendix) also entered designs, but LTV's simulation proved decisive and they were announced as the winner on August 2, 1971.Vought, System Requirements and LTV's Proposed Solution The contract stipulated that the system had to be operational on July 13, 1973.
Construction of the Airtrans guideway took place almost on-schedule, which turned out to be better than the airport itself. When DFW opened in January 1974, Airtrans, which had been heralded as "people mover of the future,' quickly fell short of expectations. Originally operating between 7 a.m. and 10 p.m., it worked reliably only 56 percent of the time. A more serious problem was the budget. Originally bid at $34 million, a series of problems led Vought to declare a $22.6 million loss on the project."The LTV Corporation"
Original specifications
Upon the opening of the airport in 1974, the Airtrans system consisted of of single lane guideway with 53 stations across the airport. Initially it carried 68 train vehicles.
+ AIRTRANS Principal Characteristics Description Value Length of guideway (single lane) Passenger stations 14 (10 off-line, 4 on-line) Employee stations 14 (10 off-line, 4 on-line) Utility stations 25 Lead passenger vehicles 30 Trailer passenger vehicles 20 Utility vehicles 17 Switches 33 diverging, 38 converging Control blocks 708 Operating speed Min. switch time 3 seconds Max. passenger trip time 20 min. intra-terminal, 30 min. to remote lots Seating capacity of vehicles 16 Max. passenger capacity per vehicle 40 All vehicles were equipped with voice communication between the vehicle and the central dispatch. CCTV surveillance was installed in passenger and employee station areas. An automatic wash facility was available for all vehicles.
Service life
In its first two years, the system carried over 5.6 million passengers over 6.4 million vehicle miles without major accidents or fatalities. Two workmen were injured by a vehicle while working in the guideway.
In accordance with the original contract specifications, Airtrans was originally built to support both freight and passenger service. Inter-terminal baggage was handled by 89 LD3 containers, which were loaded on a series of semi-automated conveyor belt systems at each terminal. During construction the airport demanded a lower required time for inter-terminal handling, and a different system had to be installed that could meet these increased speeds - the Airtrans baggage handling system was never used in operations. Likewise, the mail handling services were demonstrated at the "Air Mail Facility", but the USPS declined to use it as they felt it was too demanding in that it required their employees to interface with an automatic system. An incinerator was built for trash handling, but never worked properly and was never put into use. Instead, trash from the terminals was moved on the existing passenger vehicles after hours. In the end, only the supplies facility would use the cargo vehicles, operating with great success until 1991 when increased demands for passenger services forced the cargo vehicles to be converted to passenger bodies.Capps 2005
In service, the Airtrans system had a number of unexpected problems. The system was originally designed for typical Dallas weather, which rarely sees snow, and it was expected that the normal operations would keep the guideway clear when snow did fall. In operation, snow and ice proved to be a serious problem, but a detailed study on ways to keep the system clear demonstrated it would be less expensive to provide truck services during those rare periods.Patton, R J and Raven, R R, "Combatting Ice on Airtrans and other Guideways", TRB Special Report 185, Snow Removal and Ice Control Research, p. 328-336Stevens, R D and Nicarico, T J, "All-Weather Protection for AGT Guideways and Stations", TRB Special Report 185, Snow Removal and Ice Control Research, p. 337-342 Additionally, maintaining the vehicles proved more difficult than expected, but DFW's transportation department kept updating the system, one piece at a time. Wiring and electronic components were moved inside the Airtrans cars; they had been exposed to weather under the cars. Circuit boards were replaced with microchips. After fifteen years of continual improvement, the system emerged as a paragon of reliability. At its peak in 1987, the system carried 23,000 passengers a day. In 1988, now operating 24 hours, the system achieved a 99.8% in-service record. In 1989 the vehicles were refurbished to improve maintenance and cleaning operations.Dallas Morning News, January 8, 1989 When Airtrans made its debut, it used eight-track cartridges for its announcements; the audio system was later upgraded to a cassette system, and still later to a digital voice synthesizer.
The system was originally installed in an era of very different security concerns, and operated on both sides of the modern secure/insecure line. The insecure side was used by passengers moving between the terminals and to and from the parking lots, the secure side for employees moving around the airport and for cargo services (when they were used). This forced employees to transit through security when moving to and from the line when new security arrangements were added. A solution to this problem was easily implemented by moving the employee side doors to the opposite side of the platform, then sending in some of the cars "backwards" so the doors were on the other side. With this change the new routes became the "Employee Train", while the passenger side became the "Airport Train". Another modification was added between 1990 and 1991 to service American Airlines passengers moving between terminals 3E and 2E (today known as Terminals A & C), known as the “TrAAin" or "AAirtrans Express". An additional crossover connecting east and west sides of the airport was added to the system in 1997 and 1998.
As the original lifetime of the vehicles approached, DFW started studying replacing the system. As LTV had long exited the transit business, and no other companies offered similar AGT systems that could be adapted to the existing network, an entirely new system was needed and eventually won by the Bombardier Innovia APM 200. Since the system required entirely new guideways, the Airtrans system would have to be kept operational while the new system was installed. A mid-life upgrade process, mostly guideway improvements, was implemented in 1998.John Graddy, "Dallas/Fort Worth Airport Train Critical Needs" Passenger operations started to wind down in 2003, replaced by a shuttle bus service. Employee Train operations ended on May 9, 2005, followed by TrAAin on May 20. The new Skylink service opened the next day.
Other developments