A NT$4.13 million public-art bus shelter in Taipei has been leaking rust-stained water and sprouting withered rooftop plants before it has even opened — an embarrassing test of the city government's inspection and acceptance procedures.

• The "Clustered Floating Isle" bus shelter beside Muzha Park in Wenshan District has yet to open, but its rooftop plants are already sparse and yellowing, and after rain large yellowish-brown rust stains appear on the ground. Residents have nicknamed it the "rusty mushroom."

• The Department of Urban Development says rusting is part of the design of weathering steel, but Huaxing Borough Chief Chen Chih-ying counters that oxidation of weathering steel is supposed to form a protective layer, not wash rusty water all over the ground.

• The work is part of a NT$56 million public-art project awarded to the lowest bidder during Ko Wen-je's term as mayor. What costs the NT$4.13 million covers has never been disclosed item by item.

• The city government's account has been inconsistent: on one hand it says the project passed a 90 percent progress inspection in August, and on the other that the contractor is still doing trial work and construction is not complete.

• Chen Chih-ying is calling for the itemised amounts, contract payments and inspection milestones, and a list of defects to be remedied, all to be made public before the final inspection in October.

Outlook: Pressure is converging on the final inspection in October, when Mayor Chiang Wan-an's administration will have to decide, before making payment, whether to disclose the contract details or first require the contractor to make repairs.