The concrete deck of the elevated Honolulu rail line has cracks in a “handful” of areas that have been allowing rain to leak into the hollow interior of the structure, according to the Honolulu Authority for Rapid Transportation.

Andrew Robbins, executive director of HART, said there have been some “shrinkage cracks” in the concrete surface on top of the guideway, which is where the rails are mounted. Those kinds of cracks in concrete are common, but they are not supposed to leak, he said.

A subcontractor working on the $9.2 billion rail project discovered that water was leaking into the interior of the structure, and an inspection by HART identified a half-dozen to a dozen areas of the deck along about 1,400 feet of rail line in the Waipahu area that were leaking, Robbins said.

“Water should not be coming through,” Robbins said. Shrinkage cracks are normally patched with epoxy, and that was done in these areas, but “in these particular locations, the repair didn’t take, and water was able to get through there.”

Rail contractor Kiewit Infrastructure West Co. has agreed to make the necessary repairs and seal the cracks at no cost to the city, he said. The board of directors of the rail authority will be briefed on the issue Thursday.

The rail project already has had to cope with a series of construction-related problems, although the rail authority says each of the issues has been resolved.

>> In 2016 the rail authority acknowledged that strands in three of the tendons that help keep the guideway structure in place had snapped apart during construction of the West Oahu Farrington Highway segment of the project. Those tendons are essentially cables that wire together the individual 10-foot precast concrete segments of the elevated rail line.

Kiewit conducted an investigation into the problem and then agreed to set up a 20-year acoustical program to monitor the tendons.

According to a briefing by HART officials in May, acoustical sensors will be deployed along 61 spans of the rail line that the city identified for monitoring, and Kiewit will use that equipment to detect the sound of any future wire breaks so the city can respond to the problem.

>> HART also has struggled to design and fabricate the canopies that will provide shelter for passengers on nine station platforms on the western portion of the 20-mile rail line.

The canopies were designed by the engineering company AECOM, but Robbins has said there have been problems “with the manufacturability or constructability” of the canopies, which are essentially metal frames with material stretched over them.

The metal arms of the canopies have cables and conduits running through them to serve electronic components in the stations such as lighting and communications, and Robbins has said HART had to make “certain tweaks” in the design in order to build the canopies.

The canopies are supposed to be completed and installed by December, but in April a consultant for the Federal Transit Administration warned the problems with the canopies likely will trigger a claim or change order from contractor Nan Inc.

>> Most recently, HART reported last month that contractor Hitachi Rail Hono­lulu Joint Venture will have to retrofit two dozen rail cars that already have been shipped to Hawaii after samples from the cars failed roof and floor fire testing in Texas in February.

Hitachi, which was formerly known as Ansaldo, has opted to retrofit the floors of the Honolulu rail cars with a thin layer of stainless steel to ensure they will pass the fire testing, HART officials said. Hitachi will pay for those retrofits, city officials said.