52 • JUNE 2008 • ROADS & BRIDGES WWW.ROADSBRIDGES.COM

BY TARA VANTIMMEREN

ASSOCIATE EDITORASSOCIATE EDITOR

L I G H T E Q U I P M E N TL I G H T E Q U I P M E N TMeanwhile, projections for traffi c volume on I-35E, the main artery into and out of the city from the north, show an increase of 45% by 2025. To alleviate the problem, the Dallas Area Rapid Transit (DART) has com-mitted to building out several parts of the system throughout the city. Dallas-based Dowager Construction is handling the southeast corridor of DART’s Green Line extension, which when complete will add 27.7 miles and 20 stations to the system and run from the historic Deep El-lum section of the city northward to Farmers Branch/North Carrollton. According to Madison Smart, the fi rm’s project superintendent, the job is massive but is still only a portion of the overall light-rail expansion.

DARTing out of traffi c“There are also ongoing extensions to the Orange and Blue lines,”

Smart said. “All told, DART has budgeted $1.67 billion to build out sev-eral parts of this project throughout the city. It is, at least for the time being, one of the largest transportation projects in America; this section alone carries a price tag of $375 million. Studies have shown that light-rail growth like we are seeing here helps create pockets of specialized developments, both commercial and residential—a real plus for the local

Site dumper turns potential troublesome facet of project into an exercise in effi ciency

There is little de-

nying that an ex-

pansion of rapid

transit in the

Dallas area is sorely needed. It

is reported that northern Tex-

ans spend, on average, about 61

hours of every year sitting in

traffi c.

economies. It is also believed that the expanded rail line will help join north and south Dallas, areas that have traditionally been divided by the Trinity River. There are a lot of benefi ts to this expansion.”

Because Dallas has hundreds of miles of rail lines al-ready in place throughout the city and surrounding ar-eas, DART has acquired rights-of-way on some of those existing rail lines and is building the new rail for the bal-ance. In areas in which new track is being put down, said Smart, efforts have to be made to ensure that groundwa-ter fl ows away from the track bed.

“That involves installation of an underdrain system, and we are doing a huge amount of that type of work on this project—more than we’ve ever done on a single job,” he said. “In fact, by project’s end, there will be better than 120,000 ft of underdrain—about 25 miles’ worth—in place to help draw water away from the rail bed.”

The underdrain process involves placement of a layer of aggregate and, according to Smart, given limited ac-cess to some areas, that is the facet of the job in which a Terex PS6000 site dumper is paying big dividends.

Tight confi nesWhile the overall scope of the DART project is massive,

the work area in which Smart and his crew have to op-erate is generally quite narrow, creating a unique set of challenges for material movement and placement.

“In some places, the right-of-way may be only 65 to 70 ft wide,” he said. “In other areas, the rail runs between ballast walls, which might be only 22 ft apart or less. To complicate matters further, within this rail bed area there can be things such as catenary poles, manholes for electrical and subsystem work and more. We have to get aggregate into these areas in advance of the underdrain,

and in some cases it can be next to impossible.”Perhaps the most challenging areas, according to

Smart, are the newly constructed light-rail stations them-selves, which depending upon the design can either have passenger platforms on both sides or just one in the middle.

“In station areas, the rail section can be as little as 91/2 ft wide,” he said. “What all of these different areas have in common, however, is the limited amount of work area, and because of that, the Terex PS600 site dumper has proven an extremely valuable tool to have around. At less than 8 ft wide, the unit is narrow enough to allow ease of movement, and because the dump bucket swiv-els 180°, we can get right next to the ditch, turn the bed and dump the aggregate.”

Best of both worldsAccording to Walt Robertson, sales representative for

Four Seasons Equipment, which is introducing the vehi-cles to the Dallas-Fort Worth Metroplex, the Terex PS6000 site dumper seems to provide two benefi ts that usually are self-excluding: capacity and compact size.

“Generally, you have to forsake one for the other,” he said. “If you want small size you have to accept a small payload. If you want that bigger payload, you have to give up access to tighter areas. The Terex PS6000 af-fords contractors like Dowager the best of both worlds: a payload of better than 13,000 lb and a nice mobile machine.”

Smart estimates that Dowager Construction’s portion of the DART expansion project will keep them in that area for 24 to 30 months, while the overall project will be ongoing for the next fi ve years or so.

—Larry Trojak with Trojak Communications

Crushing the competitionThe Eco-Crusher bucket attachment (Circle 901), distributed by Giberson

Enterprises LLC, allows recycle, demolition and concrete contractors to sig-nifi cantly reduce hauling and tipping costs by crushing demolition material on-site. The jaw crusher bucket attachment fi ts easily onto any brand of ex-cavator, quickly crushes concrete, bricks, blocks, basalt, aggregate and more-easily separates material from rebar, steel or copper pipe. The Eco-Crusher operates easily on small jobsites, scooping and crushing the material on-site. This reduces the number of truckloads needed to haul away the material and increases truck hauling capacity for jobs where removal of material is still needed.

The Eco-Crusher only requires one operator to run the excavator and bucket to scoop and crush the material, and it easily attaches and detaches from the excavator. For projects such as house moving or smaller demolition jobs, the attachment quickly and easily reduces foundations and other concrete mate-rial to use as on-site fi ll or sell as recycled aggregate material. On road-building projects, contractors can crush old concrete pavement to make better use of haul truck capacity. In aggregate operations, the jaw crusher bucket is ideal for general cleanup and crushing of small deposits along the face of the quarry.

ROADS & BRIDGES • JUNE 2008 • 53