The NTSB has recommended that the FAA allow Sea-Tac to add "nonstandard" markings to Taxiway T to reduce the odds of a pilot mistaking it for runway 16R during the November-February season.
The letter from the NTSB comes after six aircraft have landed on Taxiway T since its construction in 1999; the most recent occurance was an AC Jazz DC-8 in January.
Apparently, the use of large "TAXIWAY" markings and serpentine lines on taxiways has dramatically reduced the rate of mistaken runway identification at PSP, LAS, and TUS; the NTSB recommends that SEA adopt similar markings.
Full report is available
here.
hamburgler