The Dallas Area Rapid Transit (DART) has the nation's longest light rail system and opened the first line in 1996. This question concerns the planning stages before that.
Given that the system is long for a light rail system, and is primarily aligned along freeways in a star configuration - all lines lead to downtown with no lateral connections between the legs until downtown, it seems commuter focused to bring people from the suburbs to downtown. Why then, was light rail selected? Why are there frequent stops through 30+ miles of low density suburbs in each direction where most riders are driving to the station? Wouldn't medium rail with fewer stops have made the system more competitive with driving times?
Are there any resources available to learn about why these seemingly (to me) poor/bizarre choices were made?
Dallas is very similar to nearly all the other North American cities that have built rail transit since 1980 in using light rail as a primarily commuter rail operation. After the success of Calgary and San Diego’s pioneering use of off-the-shelf vehicles and inexpensive right of way, federal transit funding favored light rail over heavy rail. In the last 15 years, this preference has shifted a bit, to encourage bus rapid transit.
There was a lot of agonizing over the proper mode in Dallas, as a couple of prominent local politicians had caught monorail fever. As a result, a mode choice study was done that received a lot of attention. The study recommended light rail, though in many respects (equipment weight, extensive grade separation, station spacing) it could be considered a pre-metro.
When DART began planning, they quickly reached the decision to use surface running in Pacific Ave rather than digging a very expensive subway through downtown. No underground tunneling was anticipated anywhere; the Red Line tunnel under the North Central frontage road was a happy accident of timing when the reconstruction of North Central offered an opportunity for inexpensive tunneling. Like most American light rail networks, DART planned to make extensive use of old freight railroad rights of way, but strenuous Park Cities opposition to use of the Katy line (now a bike trail) put a kink in the original plans for the northern line.
DART speeds are at the high end of those achieved on urban rail systems all over the world. Only completely grade-separated networks like Washington Metro or BART run any faster, and only a bit faster at that. Suburban rail networks run express services at higher speeds, but over much longer distances between stations. Station spacing for 20th century cities like Dallas is always a tradeoff between short travel times for those boarding in the suburbs and encouraging walkable density around in-city stations. If the stations are too far apart, and located where right-of-way is cheap rather than where density already exists or can be created, the system just becomes an expensive way to shuttle downtown workers from suburban parking lots.