When Corinthian Contractors was awarded a subcontractor bid in late 2015 to do excavation, material hauling and placement service work during phase two of the Dulles Corridor Metrorail Project, Owner Jamie Doll knew he would need the right mix of construction equipment to efficiently complete the job.

Doll, a seasoned construction professional, was in the process of purchasing two Doosan Crawler Excavators, a DX300LC-5 and DX235LCR-5, and a Doosan DL250-5 Wheel Loader from John "Stu" Munsell at the H&E Equipment Services branch in Dundalk, Maryland. His timing couldn't have been better, because the trio proved to be effective on the underground infrastructure project. 

Extending the Metrorail System 

The Metrorail expansion project would require Corinthian Contractors, a full-service general contractor, to dig 15- to 18-foot trenches several thousand feet in length, install eight manholes and dry utilities to provide electrical power for a new traction power substation near the Dulles International Airport. The new substation is part of a two-phase, 23-mile extension of the Metrorail system and will connect rail service from the Dulles Corridor to downtown Washington, D.C. When complete, it will be officially known as the Silver Line. 

"We knew we'd have some work - specifically the Metrorail project - and when we're done it will probably be a two-year project. I saw the need for the DX300LC-5 and DX235LCR-5 with the machine's power-to-weight ratio and the capability of the equipment," says Doll.

Now more than a year into the project, Doll has added three more Doosan crawler excavators, plus another DX235LCR-5 and DX300LC-5. The pair of DX235LCR-5s and the two DX300LC-5 excavators are dedicated to the Metrorail project. The equipment has proven it is capable of not only handling the heavy workload but also navigating the crowded jobsite with ease. 

Working Around a Tight Site

The reduced tail swing feature of the DX235LCR-5 excavator has been an advantage. The excavators are positioned along the median of the Dulles airport toll road, which remains open to traffic during construction. The only thing separating the heavy machinery and nearby traffic is a Jersey barrier. The DX235LCR-5 is designed to work on congested jobsites without blocking traffic in the adjacent lane and without sacrificing digging and lifting performance. 

"You can put the DX235LCR-5 anywhere and it's still got great capability," Doll says. "When you're working behind barriers, that reduced tail swing is number one. You can have confidence that the machine isn't going to impede traffic or other contractors working in the area."

The DX300LC-5 duo have been tasked with the wayside area of the project where digging through rock would present a challenge for less powerful units. With optimal swing radius, lift height and tilt position, the DX300LC-5s can lift and place loads and dig with greater productivity, completing the job faster. Even in less than ideal conditions, the DX300LC-5 is more than capable of handling the task. The permanently sealed and lubricated tracks are designed to maximize uptime. "It's muddy, it's bumpy, and when it rains the ground is very thick," Doll says. "The machines are well-suited to work through the conditions." 

The excavators are completing a wide variety of tasks in this large-scale project, from removing thick overburden to forming trenches specifically for manholes. "The excavators have the capability to dig both large areas and small areas effectively. You don't need a different machine to match different parts of the job," Doll says.

The Advantage of Telematics 

Additional technology has added to Doll's productivity since he implemented the Doosan Telematics package that provides machine intelligence, or what he likes to call "accountability technology." The system allows Doll to monitor his Doosan machines using the systems website from a computer or smartphone; he never has to set foot on the jobsite. "I can monitor hours worked, hours idled, fuel levels and maintenance hours," he says. "It's particularly helpful to productivity."

The visibility to the machines has many business and managerial advantages, not the least of which is diesel fuel cost savings. "I can look online and see in real time that a machine is at 50 percent fuel and is good for another day. I don't have to drive over and fill it up, but I know I've got to get to it the next day," he says. On a crowded jobsite, a premature refueling isn't just an unnecessary loss of productivity but a major inconvenience for the project as a whole. 

Looking to the Future 

As the Metrorail project wraps up, Corinthian Contractors has more high-profile projects lined up, including a road-widening project that Doll says is another ideal application for the excavator tag team. "The cut is accomplished with the DX300LC-5 and the utilities are installed with the DX235LCR-5," he says.

Doll knows the DX235LCR-5 will provide yet another advantage in the transition. "The DX235LCR-5 can be hauled on our lowboy from site to site," he says. The DX235LCR-5 excavator is the maximum weight that can be hauled without a permit. "Every time we need a permit to move a machine, the cost is $1,500," says Doll. "That's a nice savings."

The machines have been a smart investment for Corinthian Contractors. With more work ahead, Doll is confident his fleet of Doosan equipment is well positioned to handle the work. Whether the jobsite calls for precision in confined areas or powerful digging in wide-open spaces, Corinthian Contractors' extended fleet is up to the challenge.