Optimism is growing that a trucking shortage in Shanghai is quickly improving, providing some relief to supply-chain congestion, though major hurdles still remain.

Traffic into the city is picking up, with some logistics experts seeing activity returning to about 80% of levels seen before Shanghai’s Covid-19 lockdowns. The trucking situation in Shanghai could return to normal within the next one to two weeks, digital freight forwarder Flexport Inc. said in an e-mailed reply to queries.

Yet while increasing levels of export containers heading into the city are finally being seen, the volume heading out of Shanghai “remains muted,” logistics information provider FourKites said in an e-mail on Friday.

FourKites’ customers had an average 52% more volume brought by truck and rail into Shanghai last week compared with May 20, although levels remain 31% lower than March 12. Meanwhile, container volumes transported from Shanghai were 84% below March 12 levels.

Logistics providers are able to arrange trucking from other provinces to Shanghai, although there have been some cases of shippers in Zhejiang and Jiangsu rejecting deliveries made by drivers coming from Shanghai, according to Flexport.

The situation in Shanghai—the site of the world’s largest port—is being followed closely after a two-month lockdown impacted supply chains both within China and globally as it shut down factories and caused a massive drop in truck traffic. While the city is now officially out of lockdown, it will take a long time for production and trade to recover completely.

The easing of port congestion in Shanghai is expected to unleash a wave of containers on the US West Coast that could clog supply chains further. And Shanghai’s situation, while a severe constraint, is only one factor hampering global trade.

Citigroup said in its June supply-chains report that the global challenges look to be as acute as any time over the past two years.

“Supply-chain pressures have proved to be more persistent, and apparently deep rooted, than we had expected even a few months ago,” Citi said in the report. “Given these realities, any hopes of near-term improvement in supply-chain conditions have been shattered.”

While trucking activity in Shanghai is heading back to pre-lockdown levels of a few months ago, it’s still far from returning to pre-pandemic levels of 2019, according to data from G7 Connect.

Factories in the Shanghai area have finally begun to exit closed-loop operations, yet some manufacturers are choosing to remain below full capacity, said Kathy Liu, director of global sales and marketing at Taiwanese freight forwarder and logistics specialist Dimerco Express Corp.

Dimerco said it has seen trucking activity recover to about 80% of pre-lockdown levels. Seko Logistics Ltd. said last week it’s seen a similar improvement. But the firm warned that higher costs and restrictions still in place for areas near Shanghai could hinder the recovery.

Seko said it hopes to see more improvements after truckers stopped working during the public holiday over the weekend.