Burly guards, many of them professionals contracted from security firms, outnumbered students and professors on Hong Kong’s university campuses as teaching resumed for the new semester.

The Chinese University of Hong Kong was the first of the local tertiary institutions to reopen its buildings and halls to returning students, after extensive repairs and decontamination which cost tens of millions of Hong Kong dollars.

The CUHK cut short its previous semester and canceled congregation ceremonies after its campus in the New Territories was gripped by anarchy in the thick of the turmoil in November, when hordes of radicals descended on its lecture halls and dormitories and locked down the university for days, defying a tear gas bombardment by riot polic.

Security checkpoints were set up at the entrances where the identities of students and staff members were checked, and visitors had to produce a special admission permit issued by the university’s management.

But when people were allowed in, getting around the sprawling campus perched on a mountainside was a challenge as students and staff returned to their offices and dormitories and tallied up their losses.

Getting around was made difficult because the university’s buses were either vandalized or burned by rioters during pitched battles to hold back police trying to break into the fortified campus.

The university has scrambled to reroute lines and hire third-party coach companies to meet the demand when its 20,000-plus students return.

A few locations including the No 2 Bridge straddling a major expressway and rail line to downtown Hong Kong, the main “battlefield” where hardcore protesters clashed with police who tried to stop them hurling objects below, remained closed.

The university also used an independent laboratory to test air, water and soil samples collected across the campus to determine the amounts of residual CS smoke components and other possible carcinogens including dioxins and cyanide, amid concerns the tear gas fired there could lead to health hazards.

The results of the four batches of samples tested showed the amounts of containments were well below their respective international guidelines or the Hong Kong government’s ambient air monitoring standard, so the threats are negligible.

CUHK President Rocky Tuan, who had acted as a mediator between protesters and the police but was hit by tear gas, wrote in a letter to all university members that the campus had once again “sprung to life in full” for the new term.

“The new term can start as scheduled should not be taken for granted, and all credits must go to those colleagues in various capacities who have gone many extra miles in enabling the continuation of our activities, in ensuring safe passages and environs for our returning staff and students, and most importantly, in building great rapport as we weathered the storm,” he wrote.

“Some inconveniences are to be expected, particularly in the initial period of the term, and I must ask for your patience and understanding in allowing time for the campus to ease back to its former state of diversity and vibrancy.”

The university also noted there had been no substantial drop in the number of students from mainland China and overseas, most of whom were evacuated in November, some with help from the police, when radicals began to throng to the campus.

Before the reopening of the CUHK campus, staff with MTR Corp, Hong Kong’s metro operator, worked flat out to clear the nearby University station of debris and reinstall damaged equipment.

The same group of protesters who occupied the university trashed the station and set platforms, control rooms and even ticketing machines and turnstiles ablaze as they vented their anger on the rail giant for suspending services.

The Education University of Hong Kong also resumed classes, while the University of Hong Kong, whose new semester will start later this week, reopened its campus to the public and stopped security checks of visitors, now that the tensions in the city have largely eased.

The Hong Kong Polytechnic University, another learning hub hard hit by the protests in November, is yet to announce the start of its new term.

The university is still cleaning up its campus after police handed back control in December, following a week-long siege operation to round up troublemakers hiding inside its buildings.