Reporter describes confusing taxiway markings that may lead to a runway incursion.

Attributes
ACN	1171147
Time
Date	201405
Local Time Of Day	1801-2400
Place
Locale Reference	PDX.Airport
State Reference	OR
Environment
Light	Daylight
Aircraft 1
Make Model Name	Large Transport
Operating Under FAR Part	Part 121
Flight Phase	Taxi
Flight Plan	IFR
Person 1
Function	Other / Unknown
Qualification	Air Traffic Control Fully Certified
Experience	Air Traffic Control Time Certified In Pos 1 (yrs) 7
Events
Anomaly	ATC Issue All Types Deviation - Procedural Clearance Ground Incursion Taxiway

Narrative:

Aircraft X was issued taxi clearance to runway 28R via taxiways K; V; and a. Read back was accurate. While taxiing the aircraft turned on A5 and joined a. V is the next taxiway after A5 if taxiing eastbound for runway 28R. Twy V is preferred by ATC since A5 leads directly onto runway 28R and V does not. Also aircraft often exit runway 28R on A5 (high speed exit) so an aircraft mistakenly using A5 it is at risk of an opposite direction issue with aircraft exiting runway 28R. This specific mistake has been observed numerous times by many different air carriers. Possible reason for why it happened are confusing signs and markings on the taxiway. Take a look at the taxiway signs and markings to see if they can be improved.

Original NASA ASRS Text

Title: Reporter describes confusing taxiway markings that may lead to a runway incursion.

Narrative: Aircraft X was issued taxi clearance to RWY 28R via taxiways K; V; and A. Read back was accurate. While taxiing the aircraft turned on A5 and joined A. V is the next taxiway after A5 if taxiing eastbound for RWY 28R. TWY V is preferred by ATC since A5 leads directly onto RWY 28R and V does not. Also aircraft often exit RWY 28R on A5 (high speed exit) so an aircraft mistakenly using A5 it is at risk of an opposite direction issue with aircraft exiting RWY 28R. This specific mistake has been observed numerous times by many different air carriers. Possible reason for why it happened are confusing signs and markings on the taxiway. Take a look at the taxiway signs and markings to see if they can be improved.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.