The Army has disposed of millions of dollars worth of usable construction equipment at fire-sale prices and replaced some of it with expensive new vehicles that can't do some jobs as well as the older, discarded machines, a congressional leader has charged.

The $500 million program that purchased 5,000 new heavy construction machines to outfit the Army worldwide with new bulldozers, scrapers and other construction equipment was "premature and inadequately justified," John D. Dingell, chairman of the Oversight and Investigations Subcommittee of the House Energy and Commerce Committee, said in a letter to Defense Secretary Frank C. Carlucci.

Army officials say they bought the new equipment in recent years after maintenance and spare parts problems on older vehicles began dramatically reducing readiness rates of units that would build roads, runways and front-line tank trenches during war. An Army spokesman said yesterday the current readiness rate of the new equipment is classified information that cannot be released.

Although the Army said it disposed of the old equipment properly, Dingell has asked Carlucci to determine whether the Army can retrieve usable equipment that has not yet been sold. He also asked Carlucci to consider restoring a freeze on disposal of excess equipment imposed by then-Defense Secretary Caspar W. Weinberger in the early 1980s after disposal abuses of Air Force engine blades were revealed.

An investigation by the General Accounting Office (GAO), the congressional watchdog agency, could find "no evidence that the Army had measured the cost-effectiveness of keeping vehicles that were in good condition," Dingell said in his Jan. 4 letter.

The GAO found that some usable vehicles were sold to Portugal for about $240 each. Others, some of which "appeared brand new," were given to various states for the cost of shipping the equipment from the Army disposal site to the state. The agency said replacements cost from $74,000 to $148,000 each. Reviews of Army records showed that some older vehicles could have been repaired for costs ranging from $300 to $13,000 per machine, the GAO found.

Army spokesman Lt. Col. John Chapla said the Army's problems with the old machines -- some of them 30 years old -- were far more extensive, including lack of standardized equipment. He said machines were built by 15 different companies and, in some cases, construction battalions were issued different models of the same piece of equipment.

"You can imagine what a problem that was in terms of repair, getting parts, trying to maintain the equipment and training people," Chapla said. "In some cases, the commercial manufacturer went out of business and the parts weren't available."

Chapla said the Army found cases in which equipment sat useless for up to a year waiting for repair parts. He said the Army decided in the early 1980s to buy commercially available bulldozers, scoopers and scrapers when efforts to develop special military-adapted equipment took too long.

But, according to documents obtained by The Washington Post, some field commanders have complained that new scrapers that scrape top soil from construction sites must be pushed by bulldozers to be effective, tying up the bulldozers from other work. Army officials said more bulldozers were allotted to battalions for use with the scrapers so other work would not be jeopardized.

Other reports showed the new scrapers are susceptible to rolling over and require more frequent stops on convoys because the tires get "hot, sticky and soft after 30 or 40 miles of traveling along paved roadways."

The same reports said, however, that the new scrapers were better than the older models in many ways, including better maneuverability and fewer maintenance problems.