Commercial Fixed Wing
Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Confusion; Troubleshooting
ATC Issue All Types; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy; Ground Event / Encounter Ground Equipment Issue; Ground Incursion Taxiway
Flight Crew Became Reoriented; Flight Crew Requested ATC Assistance / Clarification
Airport
Last day of 3 day trip.  Started both Engines and joined the long line of departures.  Had a closeout; completed all the checklists and taxied J; K7 short of Y.  We also requested numbers for tailwind takeoff (10 knots). Somewhere in between we received an ACARS that closeout had been deleted.  Holding short of Y; Ground told us we were next to taxi to W and hold short of 9L.  At that point we questioned ourselves if we had the closeout (it had been a 40 minutes or so since out).  We realized that no numbers had been sent since the message of closeout deleted.  The First Officer (FO) notified Ground and then Ground instructed us to turn right on Y and hold short of Approach End.  Ground told us to next time to tell them sooner; since there were many behind us. I made the turn to Y immediately to get out of the way and was looking for any signs that designated the Hold Short Point.  I must have missed it or went past it while turning into Y. Since they were landing on 9R and taking off 9L my brain went into looking for any hold short point (not as familiar with PHL as I would like to be). I was thinking 9R.  The next point I saw was the ILS sign short of P.   We stopped short of it. We were told that when able to call a number.  When I talked to them they said that they were concerned since they have been told that there are no signs or poor signs around K; Y and that approach end.  The main reason they wanted us short was to avoid damage from aircraft taking off.  [Contributing factors include] communications; sense of urgency; heavy workload; poor markings; no approaches to 9L; wrong picture in brain.  For PHL; do not instruct pilots to turn K onto Y and hold short of Approach End; there isn't enough room to complete the turn and hold short.  The aircraft will be blocking K anyway if holding short.  Also; hold the critiques of not notifying them of closeout until we are stopped.  Next time I will do what I have done for XX years; make sure I know the entire route (taxiing) on the chart instead of turning immediately and looking for signs.
Air carrier Captain reported a taxiway incursion at PHL airport and cited signage and marking issues as contributing factors.