IT NEVER SHOULD have taken a half-century of false starts, second thoughts and third-rate excuses for backing off, but now the serious paperwork is moving along and the intercounty connector linking Montgomery and Prince George's counties may materialize at last. The benefits of this east-west highway should go well beyond its obvious role as an urgently needed travel route; according to an independent study commissioned by the Maryland State Highway Administration, the proposed highway would add jobs, save travel time and encourage Maryland businesses to remain in the state. Those are hardly novel conclusions, but the statistical projections of the study are noteworthy.

The report says the 18-mile toll road would help generate nearly 17,000 jobs, more than 60 percent of them in the service and retail industries and a small percentage in the top-level executive range. Best of all, the study forecasts major benefits for Prince George's County, where members of the county council have opposed the road on the curious grounds that it would pull businesses and jobs out of Prince George's and replant them elsewhere.

Why must that be? The proposed connector won't be one-way. In fact, the study estimates that the economic benefits of job creation would be proportionately greater for Prince George's than for Montgomery. Considering the attractive land available in Prince George's, it stands to reason that the county could enjoy a sizable share of the economic action. "It makes Prince George's County a more attractive place to have a business," noted Maryland Transportation Secretary Robert L. Flanagan, "and it creates encouragement for existing businesses to stay where they are."

Direct links to Baltimore-Washington International Airport and the Port of Baltimore are attractions as well. The report estimates that residents and businesses could save as much as $300 million a year through more efficient travel times.

Some opponents have said the study is flawed because it compares the impact of the connector only to having no connector. They say that more mass transit and better business development planning would attract more activity at underused Metrorail stations. Fine, bring it on, but the constant growth in this region demands a multi-model approach that must include an intercounty connector.