3D Image

Magazine Articles

Construction Magazine Cover Should You Use An Earthwork Services Bureau?
- By Dave R. Zimmerman, C.E.O., Earthwork Services, Inc.

Computers and digitizers in recent years have revolutionized the earthwork take-offs process by allowing the computer to do the tedious calculations that are done over and over again across the site. Some of these computerized earthwork take-off systems also have the ability to plot color graphics of each project, which are very helpful in bidding work and filing for change orders. Computer systems, however, come with their own set of risks. Aside from the initial cost of a powerful, full-featured earthwork take-off system ($15,000 to $25,000), buyers are faced with the challenge of finding and paying a competent operator - someone who understands the abilities and limitations of the software and can manipulate the computer to model and calculate the terrain correctly.

These problems have created a new industry of computerized earthwork take-off service bureaus that specialize in providing computer-aided earthwork estimating for the construction industry. Earthwork service bureaus, using state-of-the-art computer equipment in an assembly line manner, can produce a high number of take-offs perday at a low cost. The very nature of specialization requires extensive job knowledge and efficiency in reducing overhead costs. Service bureaus can departmentalize the various aspects of the work, including quality control. This is one step better than most in-house methods, in which an estimator checks his own work after many hours at a computer station with numerous interruptions.

A poorly trained operator can make huge mistakes in digitizing that appear to be high quality work to the untrained eye. Because of this, many large general engineering contractors have policies in place that require a second take-off on grading items exceeding a certain dollar amount. Competent service bureaus have the continuous work flow, work variety, training, and ongoing quality control to adapt software to specific client needs.

Robinson Construction Inc., a general engineering and construction company in Kent, WA, owns a state-of-the-art earthwork take-off system yet still sends much of its work to a local service bureau. "The earthwork take-off bureau we use provides expertise in deciphering and then calculating difficult grading plans, and acts as a confidential source to use for overflow work, which frees up key personnel for less tedious tasks," says Pat Gailey, vice president.

Scarsella Bros. Inc., an AGC member and second-generation heavy/highway contractor in the Seattle area, uses a service bureau in bidding large excavation jobs. Says Frank Scarsella, vice president, "Using a computerized take-off service has saved us a lot of time, and its reports have provided us with invaluable information in calculating the true costs of earthwork construction."

- Dave R. Zimmerman has a B.S. in Construction Engineering and 10 years of experience in providing computerized earthwork services to the civil engineering and construction industries.

Construction Magazine Cover Earthwork Take-offs To Go
- by Bill Welgoss, Pit and Quarry / May 1991

When Associated Sand and Gravel's Engineer and Property Manager, Jerry Crane, figures stock inventories and excavations, he calls a computerized earthwork take-off service. Within two days he receives a report with color graphics of earthwork volume estimates for a given area. "I've done a lot of stock piles - physically ran up and down these things - so to me this service is a godsend," said Crane. Crane, a 27-year sand and gravel industry veteran, recalls when he calculated the volumes manually by the average-end-area cross-section method. He plotted cross-sections at 100 - to 200- ft. intervals off a base line drawn on a topographic map of the site. He then manually measured each section. This was a laborious process that could take up to two weeks per site and left much room for error.

As Associated Sand and Gravel expanded, Crane started using a mapping company to calculate inventories. From aerial photographs, the company created topographic maps of the pit before and after excavation. At this point, Crane used to figure volumes manually, but now he hands over the work to a computer at an earthwork service bureau.

Crane used to call a consultaing agency that used a planimeter method for calculating volumes. "It was a good method," said Crane, "but it was a lot more expensive. [The service bureau] does the work for about 25 percent of what it used to cost."

At the heart of take-off services is the computer technology that is now available.

Computers have revolutionized the earthwork take-off process by performing the complex geometric calculations that must be done over and over again across the site.

A computer can create cross-sections, or grid calculations, at a very tight interval (one cross-section for every one-half foot) and can calculate the volumes free of mathematical error.

A computer can also provide valuable graphical information such as three-dimensional color views of the site, color-coded excavation depth maps, and plotted cross-sections. They can account for strata layers defined from boring logs and break out and sub-categorize individual surfaces, such as stock piles from the total excavation volume.

Computers have also helped in the designing of pits and quarries. Once the excavation limits (top and bottom of site), side slope specifications, benching and corner requirements are defined, a computer can quickly create a design and then plot design contours. Alternatives can be analyzed, and with a few changes entered by the operator, an optimum design can quickly be reached.

Computer systems, however, come with their own set of problems and risks. Aside from the initial cost of an earthwork take-off and engineering design system ($13,000 to $15,000), one is challenged with the difficult processof bringing the system on-line and finding a competent operator. This scenario has opened opportunities for earthwork take-off services that buy state-of-the-art computers and software to provide earthwork volume calculations for mapping companies, engineering firms and pit and quarry companies.

For Associated Sand and Gravel, precise earthwork measurements have become a matter of turning a profit.

Recently, the Everett, Washinton pit reached its boundaries, and required site reclamation, which has become a major cost factor.

"We're the second largest landowner in the city of Everett," said Crane. "We have 300 some acres in the city limits and land is worth about $5 a square foot, so you tend to do things the right way."

Tight earthwork measurements have also been crucial because of the overburden the pit encounters. The company hires contractors to strip as deep as 40 ft. to reach reserves. Reliable figures are the best defense in contracting disputes.

When Associated first started using an earthwork tke-off service, the company ran into a problem with a contrctor who, coincidentally, was using the same service.

"There was a situation where there was about a 40,000 or 50,000 yd. differential. But with the data [the take-off service] produced with isometric pictures, it was very simple to figure out where the differential was," said Crane.

The service Crane uses, Earthwork Services, Inc., located in Cosmopolis, WA., provides a complete audit trail in the computer reports and plots so discrepancies can be quickly identified.

"After we defined the limits and showed the contractor, there was no question that they were totally in accord with us," said Crane.

Another area in which an earthwork service bureau is helpful is in site feasibility studies. For a recent site that Associated considered, Crane photocopied the area in question from a USGS map (1" = 720'). He then sketched the proposed pit and 50 ft. design contours onto the photocopy and sent a fax to the service. Two days later, he received in the mail a complete earthwork analysis and a bill for $35.

Costs of earthwork services are low because they offer technical services and not consulting. Earthwork services tend to charge about half of what a consulting firm would charge for similar services.

Crane points out that obtaining maps for the service is the biggest expense: "It costs $700 to send a plane up to get photos. To produce a topography map, the cost depends on the area. If you're handling 30 acres, it's probably going to cost you a couple thousand dollars."

Considering the costs for mapping, says Crane, the bigger the project, the more beneficial using an earthwork service becomes. For small estimates, Crane still uses manual methods to measure hills: "It's not as accurate, but its good enough for our purposes."

Although earthwork take-off services are still new to the pit and quarry industry, Crane says it is well recognized in his area as "as good a method as you can come by" for figuring earthwork volumes. Jerry Crane should know, he's been up and down a hill or two.

1991 Pit and Quarry Magazine