Dave Foster wondered why an $11 million consultant's draft report says a rail line parallel to Interstate 81 is twice as steep as it really is.

Megan Gallagher and others in the Shenandoah Valley Network, an activist group, noted that two pages in the report appear to give widely different estimates of the farmland to be affected if the highway is widened.

People can check out those "gotchas" at public hearings the Virginia Department of Transportation will hold during the next two weeks in cities along I-81's 325 miles in Virginia.

The first hearings will occur tonight at the Wyndham hotel in Roanoke and at Wytheville Community College.

Activist groups have been poring over the 1,800-page draft environmental impact statement since it was released in November, looking for anything to support their arguments that VDOT wants to widen I-81 more than they think is necessary.

Their scrutiny doesn't bother Fred Altizer, who's managing the Virginia Department of Transportation's I-81 study process. It's called a draft report for a reason, Altizer said.

"I'm glad somebody is looking at it this close," Altizer said. The report can be changed to fix errors revealed in the public review process, which continues with public hearings through April 19. Written comments received by VDOT through April 29 also will be included in the review process.

Hunt Riegel of Glasgow noted a math error in the report's Environmental Consequences chapter. In a table that predicts fuel consumption in 2035, someone in the consulting process used the wrong method.

"This table lists potential energy consumption, but incorrectly multiplies the miles traveled by 27.5 miles per gallon [rather than dividing]. If we are to believe that table, it takes us 27.5 gallons per mile to drive on I-81," Riegel said.

Altizer said the math error had been pointed out earlier.

VDOT signed Watertown, Mass., consultant Vanasse Hangen Brustlin Inc. in 2003 to conduct the first level of environmental review, called Tier 1. The contract was valued at $10,955,273. Nine other consulting firms contributed to the report.

Foster, a Salem resident and executive director of the Rail Solution advocates group, zeroed in on two things that bothered him about the draft.

First, he noticed that it constrained its evaluation of railroads' ability to take freight off I-81. The study focused on improving rails in the 325-mile corridor in Virginia, but ignored other states that I-81 goes through.

Nearly all rail experts say trips shorter than 500 miles are more efficiently handled by truck, while rail shipment becomes economical on longer hauls, Foster said.

But one clear-cut discrepancy came in the report's description of the Norfolk Southern Railway's most direct route between Bristol and Winchester, called the NS Shenandoah division.

The Transportation Technical Report portion of the draft statement says the Shenandoah line has "numerous grades approaching 4 percent."

Norfolk Southern's Track Chart for its Virginia division, dated 1990, shows the steepest grades in the Shenandoah division are just 2 percent. And the steepest "ruling grade," the long, uphill haul that determines how many locomotives are needed to pull a train, is a 1.8 percent grade near Rileyville, north of New Market.

Foster cited other examples that, he said, call the report into question. The report states that the NS track between Danville and Manassas on its Piedmont division, the north-south freight route NS uses most, "is on level grade." In fact, the Piedmont division has a "ruling grade" of 1.42 percent near Charlottesville, NS said.

Assertions such as those, Foster said, "make the Shenandoah line seem worse than it really is."

Responding to those criticisms, Craig Eddy at Vanasse Hangen Brustlin said the company received the rail-line information from Norfolk Southern but it was "in some instances misinterpreted by the I-81 study team. All incorrect statements will be corrected" in the final document, Eddy said.

"The statement regarding 4 percent grades should have read '2 percent grades.' There are no 4 percent grades along the rail corridor," Eddy said.

Rail Solution's announced goal for several years has been to get the Shenandoah line upgraded, possibly with some help from government funding. The group says a better Shenandoah line would mean more freight could move by rail, resulting in fewer trucks on I-81.

VDOT has said that while better rail lines could slow the increase in truck traffic on I-81, the number of trucks nevertheless will continue to rise. The demand for freight shipments will grow faster than rail alone can match, VDOT's studies predict.

Gallagher and fellow members of the Shenandoah Valley Network focused on how a widened I-81 could affect farmland, tourist attractions and other aspects of the valley's quality of life.

Two charts in the report's "Environmental Consequences" chapter cite different figures on the amount of farm acreage that could be affected by the widening.

A maximum widening's "impacts to land use" for acreage designated for "agricultural/pasture" use a total of 5,095 in one chart. Another chart in the same chapter says a maximum widening could affect more than 12,000 acres described as "prime farmland" or "soils of statewide importance."

The description for the 12,000-acres category covers a range of soil types rather than actual agriculture use, according to U.S. Department of Agriculture terminology.

People can e-mail their comments to 81info@VirginiaDOT.org. An online comment form is available at www.I-81.org.

Written comments can be mailed to Christopher Collins, project manager, VDOT Environmental Division, 1401 E. Broad St., Richmond, VA 23219. The deadline for those comments is April 29.