Soviet troops, now concentrated in five areas ringing Poland, have begun patrolling roads leading into that country, and specialists here are watching for signs of joint Soviet-Polish military "maneuvers" which could serve as a cover for bringing large numbers of Russian soldiers inside Poland.

Though the Soviets, according to administration officials, have an invasion-sized force of close to 30 divisions poised in the western regions of the Soviet Union, Czechoslovakia and East Germany, the expectation here is that if Moscow does intervene it may come in a more subtle form than an outright charge across the borders.

A straightforward invasion of Poland, a volatile country of 35 million people with a deep streak of nationalism, would almost certainly meet with resistance, possibly from Poland's army, 220,000 strong and backed by thousands more in the reserve and militia.

But if the Soviets, at the invitation of Poland's beleagured Communist Party authorities, were to be invited to take part in joint Warsaw Pact maneuvers with Polish forces inside Poland, then it is believed here that Moscow could move far larger forces into Poland than the Polish population would initially suspect. At the same time, such a tactic could serve to neutralize the Polish army because the Soviet army would be intermingled with it in the field.

In this scenario, the maneuvers would be accompanied by moves to stifle internal dissent within Poland, with the Soviet troops backing up Polish security authorities is necessary. This would be accompanied by statements from Warsaw and Moscow that these moves were only directed at anti-socialist "counter-revolutionaries" and with pledges of fidelity to previous agreements with trade unions. With such measures, some senior specialists here believe, Moscow might calculate it could gain control of the situation in Poland quickly and without being excessively brutal.

The manner in which the Soviets intervene in Poland, if they do, is viewed as crucial in both the East and West.

The Carter administration has made clear it would view any Soviet intervention, even in the guise of military manuevers, in the gravest of terms. The Soviets, however, might be able to starve off very hard-line economic and political reaction from some U.S. allies in Western Europe -- and keep their other satellite countries in Eastern Europe from boiling over -- by using the joint manuever tactic as opposed to a more heavy-handed invasion that produced a prolonged and bloody struggle in Poland with refugees fleeing in all directions.

Administration officials yesterday said they still didn't know if the Soviets had in fact made the decision to intervene at some point. But they provided additional details about the "quite extensive" Soviet preparations and buildup, which are continuing.

Aside from "reconnoitering" access roads, the Soviets have set up medical facilities and fuel and ammunition dumps near the Polish border. A large concentration of Soviet divisions is centered around Kalingrad, just north of the Polish border. Other Soviet units are inside the Soviet Union but opposite Warsaw and Krakow.Soviet and Czech divisions are positioned in Czechoslovakia to the south with another major concentration of Soviet forces in East Germany opposite the northwestern corner of Poland.

Of the roughly 30 divisions, officials said most are Soviet and few are Czech. Few, if any East German units are said to be involved, with Moscow perhaps mindful of the reaction that German troops might cause inside Poland.

Since Soviet preparations for intervention began to take clear shape last weekend, the administration has made public the broad outline of this threat. Officials claim this has been a successful tactic in the sense of letting the element of surprise away from Moscow while alerting the Poles to information they might not have, and in focusing world attention on the crisis in the hopes of getting Moscow to think twice.

The United States is now making a major effort to get the allies to line up behind various courses of action against Moscow depending upon how events unfold. But the Carter administration, which has never had very good relations with Western Europe, is not in a good position now to exert pressure on those countries.

The problem is complicated by the fact that Washington is now moving between administrations.

If the Soviets do intervene, the western sanction that might be most important to Moscow would be a pledge by Western Europe to cut off major trade, credit and joint projects with the Kremlin. This could be more important than any step the United States might take on its own. Relations between Washington and Moscow already are very bad and Soviet trade with Western Europe is much larger and more important to the Kremlin than is trade with America.

Administration officials said yesterday that they are generally satisfied with the way talks have been going with the allies, though West Germany is said to be not as forthcoming as some other countries. This is to be expected, U.S. officials said. Germany remains a divided nation and the web of links to the East is of cricial importance to Bonn, both in trade and in the repatriation of Germans from east to west. Bonn's trade with the East is six times greater than U.S. trade with the East in terms of percent of gross national product.

Bonn also may not be the only nation reluctant to jump into severe anti-Soviet sanctions. For example, of Poland's roughly $22 billion debt to the west, about $20 billion is held by banks and governments in Western Europe; only part of this debt is to the West Germans. U.S. officials said yesterday that there is some "sensitivity" among the allies about jeopardizing these investments, but that this had not reached the stage where it would cripple alliance action.

The Polish crisis, therefore, could have unpredictable consequences for the West as well. On the one hand, it could galvanize the North Atlantic alliance into concerted action, something that did not happen after the Soviet invasion of Afghanistan a year ago. But if the Soviets intervened in Poland, just 150 miles from the West German border, and NATO again split over what to do about it, the demonstration of disunity would be studied even more closely here and in Moscow.