Chron: How do Dallas trains avoid accidents? It's obvious

http://www.chron.com/cs/CDA/ssistory.mpl/metropolitan/3270083

DALLAS VS. HOUSTON

Where safety, design collide
DART system's track location helps it log fewer accidents than Metro's Main Street line

By RAD SALLEE
Copyright 2005 Houston Chronicle

DALLAS - Just from looking out the train window, it's easy to see why Dallas Area Rapid Transit's light rail trains seldom collide with vehicles or pedestrians. One minute you're cruising high above the traffic on Walnut Hill Lane; the next you're zipping into Cityplace Station, 120 feet below ground.

And when the trains are at ground level, which is most of the time, they're still at a safe distance from motorists. About 85 percent of the 45-mile DART system runs on former freight rail tracks, not in the street.

This design has helped DART achieve an accident rate per mile of track that is about one-tenth of the Metropolitan Transit Authority's. The reason is a basic truth of physics: Two vehicles can't occupy the same space at the same time.

DART had 55 light rail accidents in a 31-month period through April, a monthly rate less than half of Metro's despite having six times as much track. But only two parts of DART trains run on streets. One of these is downtown, although a mile of that is a "transit mall" closed to vehicles, and the other is in South Oak Cliff, where the rails are on the median of a busy thoroughfare. DART also runs through a 3.25-mile tunnel north of downtown, and of its 34 stations, four are elevated and two below ground level.

Of the 95 street crossings in DART's system, 71 are protected by gates. Metro's 7.5-mile line has 62 crossings, 10 gated.

This difference in design between the two systems reflects a difference in function. Although DART has inner-city stations, suburban commuters are a big part of its business.

By contrast, Metro, which already has a nationally respected Park & Ride bus system for suburban commuters and intends to expand rail to the suburbs eventually, designed its Main Street line and next five extensions as "an improvement on local bus service," said Vice President John Sedlak.

All are designed to run on major streets, such as Main, Harrisburg, Wheeler and possibly Westpark or Richmond, staying inside or near Loop 610 until at least 2012.

The Main Street line has booming ridership, Sedlak said, precisely "because of how close it comes to the heart of the employment centers and the ease of access to the stations."

Metro's plans also include two suburban commuter lines on freight rail rights of way, along Hempstead Highway near U.S. 290, and following U.S. 90A (South Main) to the Fort Bend County line.

Metro probably couldn't have followed DART's example even if it wanted to, Sedlak said, because in most cases the local freight tracks were surrounded by industrial property and few residents or attractions. "You'd need massive redevelopment to make it work," he said.

Cutting accident rate

The Main Street line's 36 collisions in its first five months of operation made it the butt of jokes, but additional safety measures adopted in June 2004, including four-way red lights in Midtown when the train approached, cut the accident rate per mile traveled by three-fourths despite a doubling of service.

Several studies show that rail transit accidents increase with the proportion of transit system miles where trains share right of way with cars. In a 1994 survey of 10 light rail systems, the 23 percent of Los Angeles' track that was shared with vehicles had 79 percent of the accidents, and other cities showed similar results.

In the most common type of collision, motorists turned in front of trains approaching from behind. These accounted for 86 percent of light rail accidents in Baltimore, 56 percent in Los Angeles and a large share in other cities.

It is also the leading cause on Metro's Main Street line, where drivers in 33 of 92 accidents were cited for illegal turns. Second was running red lights, cited in 28 accidents. Only two collisions were attributed to light rail operator error.

However, each part of the line was different. In downtown, whose 25 accidents were the most of any rail segment, 14 accidents involved running red lights and seven were for illegal turns. Downtown was also the place where accidents increased after the new safety measures, from three collisions in the previous five months to 22 in the following 13.

Metro Police Capt. Tim Kelly said many of the recent accidents happened where the rails cross Pierce, St. Joseph and Jefferson near freeway entrances and exits. Kelly said this leads to higher speeds as motorists try to catch as many green lights as possible.

Views blocked

On Main, the rail tracks and a pedestrian mall have reduced street traffic to a trickle, which explains the few left-turn collisions. But at cross streets, office buildings can block train operators' and motorists' views of each other until too late, making light-running a special hazard.

In the Texas Medical Center, where the 20 collisions were second to downtown's, 15 drivers were cited for illegal turns or lane changes into the path of the train. The tracks pass through vehicle-turn lanes in a congested part of Fannin, creating a hazard for drivers who don't watch the signals and their rearview mirrors.

In Dallas, DART's president and executive director, Gary C. Thomas, who also helped design the system as an engineer, played guide on a recent tour, pointing out often how the tracks skirt residential and commercial areas but stay close enough to lure riders.

Close enough to connect

Consider for instance Pacific Avenue, which Thomas said was downtown Dallas' "back door" at the turn of the century.

"That's where all the trains were, so all the loading docks backed up on Pacific," he said. Now warehouses and other old buildings contain restaurants and lofts — part of what Thomas says is more than $1 billion in development along the system.

"It doesn't work everywhere," he said. "But in a lot of cases, although we might not be right in the middle of something, we are touching it or close enough for folks to make the connection to the rail."

At Mockingbird station, where DART's tracks emerge from the tunnel, a complex of theaters, shops and restaurants in an old telephone company warehouse is linked to the station by elevated walkways.

Following same idea

To the west, Southern Methodist University and the affluent suburb of Highland Park are just across North Central Expressway, but to the east is a commercial and industrial area and parking lots.

DART's planned northwest route will follow the same idea. "It's a block or two off the main travel corridor as it exists right now, but that creates opportunities," Thomas said.

"It isn't all that far away."