The U.S. Interstate Commerce Commission Wednesday gave opponents one last chance to make their case against the $4 billion merger of Burlington Northern Railroad and Atchison, Topeka and Santa Fe Railway before the agency votes today.

Approval would create North America's largest railroad, with 46,000 employees and $7.6 billion in revenue. Its routes would extend from Chicago to the Pacific Ocean and from the Mexican border to western Canada.With a lack of apparent vocal opposition, approval of the merger has been widely predicted.

Meanwhile, Robert D. Krebs, chairman of Santa Fe Pacific, told securities analysts Wednesday that he was not prejudging the outcome.

The ruling on the pending BN-Santa Fe agreement is also likely to be the last piece of significant business by the 108-year-old ICC, which is expected to be legislated out of business later this year.

With onlookers representing some of the country's most powerful railroads, utilities and shippers packing every corner of the ICC's Hearing Room A, 18 opponents of the merger voiced largely pro-forma objections.

As BN counsel Betty Jo Christian pointed out to the commission, virtually all of the major competition concerns harbored by connecting and competing carriers worried by the proposed merger already have been settled. The merger partners have agreed, for example, to grant Union Pacific trackage rights over Santa Fe's line between Abilene, Kan., and Superior, Neb.

Ms. Christian said the ICC's accelerated schedule to handle the merger prompted the various parties to quickly reach accords.

The commission pledged in March to decide the BN-Santa Fe case within six months, rather than the two years or more the ICC normally requires for such complex cases. The six-month schedule would result in a written decision by Aug. 23.

Mr. Krebs said Wednesday if the merger was approved that new management would be named 30 days after the written decision is issued. That group would take the balance of 1995 to set goals for financial and operating performance and begin formal implementation in January 1996.

Ms. Christian noted the compatibility of the two railroads, saying that BN operates primarily in northern U.S. corridors and ships primarily coal and grain, while Santa Fe operates in central and southern corridors and focuses on intermodal and automotive business.

"The benefits of the merger are fundamentally undisputed," Ms. Christian said. "The outpouring of over 600 (pro-merger) comments by shippers and other supporters says it all." Representatives from six railroads, four utility companies, two corporations, the Justice and Transportation departments, and four rail unions weighed in with their views on the merger.

Among the protesters was Illinois Central Railroad, which is requesting prescribed rates or divisions on traffic for a 15-year period.

Phillips Petroleum Co. reiterated its concerns regarding the expense of rail improvements at the company's Borger, Texas, facility.

Questioning merger opponents, ICC Chairman Linda Morgan sought details on how the linkage may hurt consumers.

John Leseur, counsel for the Western Coal Traffic League, said the merger would cut to three from four the number of potential rail competitors for the 95 million tons of coal the league's members ship each year, primarily via the 127-mile Powder River Basin rail corridor in Wyoming.

"Obviously a reduction from four to three does not mean there is harm to competition," Ms. Morgan said. "Can you provide specific examples?"

"Trying to quantify (the possible harm) is difficult," Mr. Leseur responded. "You have a very fragile competitive balance (in the Basin). Don't lose sight of the forest for the trees."