The faulty axle counter problem along Houston light rail lines that has delayed trains and bedeviled riders and transit officials since 2014 soon could be solved, the firm that built Houston's three newest lines said.

A speedy fix before the Super Bowl in February, however, could mean aggravation for regular riders, because it would require weekday closings of some major lines along the Metropolitan Transit Authority's train system.

"There is an appeal to a quicker schedule because we get the pain over with, but what is the impact?" Metro board member Christof Spieler said during a discussion of the issue this week.

The axle counters track trains along the lines, making sure trains can proceed safely with another light rail vehicle in the way. A combination of water, high temperatures and debris in water - especially metals and aluminum foil wrappers - cause the devices to malfunction. When errors occur, trains slow and officials must manually reset the defective axle counter to return the system to normal. Officials have grappled with the problem since the devices made by Siemens began failing a couple years ago.

The faulty devices have had a ruinous effect on the punctuality of Metro trains, especially during the hottest parts of the year. Transit officials have a goal of 95 percent on-time performance for the Red Line, meaning within five minutes of its scheduled time, something the line has not achieved in three years. In September, the line was punctual 71.5 percent of the time.

For riders, the delays translate to unpredictability and frustration. Carol Koonz, 56, said her occasional trips on the Red Line in the central business invariably include a long stop at one station.

"We just sit there, waiting," she said, waiting for a train Thursday at lunchtime. "Or you can see the train and it's just sitting there at a stoplight."

HRT, the contractor Metro chose to extend the Red Line north of downtown and build the Green and Purple lines, chose the Siemens product, and is paying to replace the axle counters. Metro CEO Tom Lambert said transit officials are assessing other costs related to staff time and using buses to replace rail service when the lines are closed to repair the axle counters.

Conceding that officials are "learning" from the complications spending two years on a replacement for the faulty counters, Lambert said the focus is now on finalizing the fixes. Officials began testing a replacement for the faulty Siemens counters in November, and the tests indicate it will work.

"We didn't have any failures of the (new) units," said Jorge Estevez, project director for HRT.

A dozen of the new units were installed along Capitol where the Green and Purple lines cross the Red Line in the central business district. Later, the new counters were installed along the Red Line north of downtown. So far, 41 axle counters have been replaced.

In both tests, Estevez said, the devices - made by Frauscher, an Austrian company that specializes in train detection systems - led to minimal disruptions, and no delays once crews calibrated them properly. That compared to the period before they were installed when the Siemens counters were defaulting roughly six times per week.

The successful tests led HRT to propose an accelerated schedule for replacing the 516 remaining Siemens axle counters along the rail lines before the Super Bowl. To do so, Estevez said, crews would close some portions of the rail lines during the workweek - when use is greatest - to install entire segments.

Metro officials have not made a final decision on whether to expedite the work. The schedule now relies more on weekend work, which stretches the total job until May.

The axle counters are one of a handful of unfinished parts of Metro's rail line expansion left, though the lines opened about 18 months ago. Construction of an overpass along Harrisburg was completed last month and Metro is now testing trains along the tracks. Officials expect the Green Line to open from the Altic station to Magnolia Transit Center in January.

Once everything is complete, Metro will then focus on resolving disputes related to the rail expansion, including any effect the axle counter delays and replacements have on the price. As of this week, Metro spokesman Jerome Gray said transit officials are withholding $21.7 million in payments on the HRT contract, pending the axle counter replacements.

Officials are also withholding $16 million related to delays and design problems with the newest rail cars, though all of the cars built by CAF U.S.A. are in Houston.