WASHINGTON (NYTIMES) - This month, many colleges in the United States plan to welcome back thousands of students into something they hope will resemble normal campus life.

But they face challenges unlike any other American institution - containing the coronavirus among a young, impulsive population that not only studies together, but lives together, parties together, and, if decades of history are any guide, sleeps together.

It will be a hugely complex and costly endeavour requiring far more than just the reconfiguring of dorm rooms and cafeterias and the construction of annexes and tent classrooms to increase social distancing.

It also crucially involves the creation of testing programmes capable of serving communities the size of small cities and the enforcement of codes of conduct among students not eager to be policed.

Who will be tested for the coronavirus and how quickly can they get results? Will mask wearing be mandated? And what will happen to tailgating, keg parties and sneaking into your partner's dorm room?

Colleges are mapping strategies as varied as the contrasting Covid-19 regulations enacted by the states, reflecting the culture and leadership of their schools.

Syracuse University is vowing to play the strict parent, requiring students to sign codes of conduct with penalties for violating Covid-19 rules more severe than the punishment for smoking marijuana.

But the University of Kentucky is presenting a more lenient front, adopting existing honour codes that urge students to "promote personal responsibility and peer accountability".

And the University of Texas-Austin has prohibited students from holding parties on or off campus, banned overnight guests in dorm rooms and warned students that they can be disciplined for "purposefully invading the personal space of others", at least without a face mask on.

All of these efforts are coming at great cost, potentially adding more than US$70 billion (S$96 billion) to the budgets of the nation's 5,000 colleges.

Yet college administrators say giving their constituents - students and their families - at least a taste of college life is worth it, if done in the safest possible way. Whether those constituents agree is an open question, and complaints about tuition have led a growing number of schools to offer rebates.

It is still possible that the frantic planning will come to naught.

Almost daily, universities that had released detailed plans for in-person classes this semester have reversed themselves and said they will go almost entirely online.

On Friday, the University of Pennsylvania became the latest, announcing that almost all undergraduate classes would be taught online and that undergraduates returning to Philadelphia, regardless of whether they were living on or off campus, would have to take a minimum of two Covid-19 tests to participate in any Penn activities this fall.

"We have learned how to close safely," Hiram Chodosh, president of Claremont McKenna College, a liberal arts school in Claremont, California, said. "But the big question now is, can we open safely?"

Testing capacity, a problem in communities throughout the country, varies widely among schools and could play a major role in whether they can remain open during an outbreak.

Big schools, from Syracuse University to the University of California, San Diego, that have connections to labs, health programs or medical schools say they are capable of processing large numbers of Covid-19 tests in 24 to 48 hours.

In a typical big-school plan, the University of California, Berkeley, will test all residential students within 24 hours of their arrival, for free, using either a standard nasal swab or a saliva test being developed by an internationally renowned genomics research lab on campus.

Students will subsequently be sequestered for seven to 10 days, leaving their single dorm rooms only to go (masked) to the bathroom or to pick up a meal from a central location in the building or outside, then retested.

If they test positive, they'll be isolated in a special dorm. (Some schools hope to create supportive communities, along the lines of an old-fashioned TB sanitarium, for students who test positive.)

After that, everyone living on campus will be tested regularly, twice a month, if the spit test proves to be accurate enough.

But little Cornell College in Iowa, with only 1,000 students, is not doing universal testing on arrival, believing that it would give a false sense of security because of the incubation period.

The school will be doing randomised rapid testing of 3 per cent of its asymptomatic students per week through its health centre, which will take just a few minutes to get results. It will reserve the more sophisticated testing, with the help of the county Health Department, for students who show symptoms. Other small schools in similar situations are finding themselves at the mercy of private labs that can take days to deliver results, making results almost meaningless.

Equally daunting is the task of regulating the behaviour of an age group known for its risk-taking behaviour.

Many schools have adopted social compacts and behaviour codes. Masks are a key part of almost every code, to be worn except in situations like brushing teeth, walking alone outside, or being alone in a dorm room.

Most ban partying or socialising outside "social pods" - the small groups of students that some colleges are assigning students to, usually based on their dorms. Penalties for code violations range from being kicked out of class and counselled, to eviction from campus housing and expulsion.

The word "sex" is not mentioned in the typical behaviour code. Some colleges may try to prohibit overnight visits in dorms, and many are stressing the obvious risks intimate contact poses of spreading the virus.

But most administrators seem to believe that a rule banning sex is unrealistic, and are quietly hoping that students will use common sense and refrain from, say, having it with people outside their pod.

"I think at some point, if you treat young people like adults, they are going to act like adults," said Gordon Gee, the president of West Virginia University.

"In the end, we're not going to patrol every aspect of their lives."

Or, as one official at another college, put it: "Could there be love in the pod? I guess so."

The behaviour codes generally apply both on and off campus, though they are clearly harder to enforce off campus, and some students say that they immediately began looking for off-campus housing when they realised where rules would be strictly supervised.

The rules of local governments also apply.

"In Berkeley, indoor gatherings which would constitute a party or are outside of your social pod are forbidden," said Dan Mogulof, a spokesman for the university. "So we are and are going to remain consistent with what the city's rules are, and we have to run everything through them."

But students say social pods, especially when assigned by administrators, could quickly fracture if one or two students have a falling out.

West Virginia University has persuaded the governor to shut down bars serving students at its Morgantown campus after a COVID outbreak in the area, Gee said. It has been in effect for about two weeks, and he would like to renew it.

"Bars get people together in small places, and they cause these kids to really, really, really get too damn close to each other," Gee said.