Flight Crew Last 90 Days 200; Flight Crew Type 8100
Confusion; Distraction; Situational Awareness
Deviation / Discrepancy - Procedural Clearance; Ground Incursion Taxiway
Air Traffic Control Issued Advisory / Alert; Flight Crew Became Reoriented; Flight Crew Returned To Clearance
Airport; Environment - Non Weather Related
While cleared to taxi out by ATC for departure on Runway 28; we took a wrong turn to enter Taxiway U. BWI Ground cleared us to taxi via Taxiways A; P1; and U. Instead we joined U from P taxiing via A; E; P; and U. Departing from the X Gate alleyway at night; contributing factors included an absence of taxiway signage; multiple illuminated construction barriers; and an aircraft on Taxiway P. When questioned by Ground about the incorrect turn; we acknowledged the mistake and no further discussion occurred. The remainder of the flight was conducted uneventfully. Taxiway signage could be improved coming out the alleyway of the X gates. Aircrews should not taxi their aircraft until ATC routing instructions are mutually understood and verified.
An air carrier pilot reported they were given taxi clearance via Taxiways A; P1; U to Runway 28; but because of night conditions; construction barrier lights and poor signage transitioned to U at P. ATC alerted about the error.