Flight Crew Air Transport Pilot (ATP)
Confusion; Distraction; Situational Awareness
Deviation / Discrepancy - Procedural Clearance; Ground Incursion Taxiway
Flight Crew Became Reoriented; Flight Crew Took Evasive Action
Airport; Procedure; Human Factors
During taxiing in for the gate; at A4 Taxiway; the position sign is in between the taxiway and the vehicles entrance making it confusing. So we started the taxi a little soon and then corrected it after we advised ATC. The area needs better lighting and markings.
Light Transport aircraft flight crew taxiing into the ramp at IAD Taxiway A4 turned early because the Taxiway signage position coincides closely with a ground vehicle access road.