Complex sentence: Although located in the middle of the service areas of DART, the Fort Worth Transportation Authority, and the Trinity Railway Express that connects the two, the city of Arlington remains the largest city in the United States that is not served by a public transportation system.
Split into simpler sentences: Although located in the middle of the service areas of DART, the third transportation service in the area is the Fort Worth Transportation Authority, and the Trinity Railway Express that connects the two. The city of Arlington remains the largest city in the United States that is not served by a public transportation system.