Cessna citation first officer reported crossing a runway without clearance.

Narrative:

We called for taxi and were told to standby. The ground controller sounded busy and a little overwhelmed. We were finally given taxi instructions to taxi via charlie; delta; left turn on golf hold short of runway xx. The PIC started to taxi out as I was busy looking at the taxi diagram to find the taxiways. I saw us approaching runway xx and the captain proceeded to cross. I was assuming that he knew the way or at least saw the appropriate signage and knew where we were. Taxiways delta and golf are not labeled on the taxi diagram and I was therefore confused. As we were halfway across runway xx; I looked down the runway and saw that an airplane had just landed and was turning off the runway. At about the same time the PIC remarked; 'I think we just crossed a runway!' we stopped on the other side of the runway and then realized there was opposite direction traffic on the taxiway and we had to do a 180. We admitted our mistake to the ground controller and she subsequently offered us the option to depart on runway xx which we accepted.looking back; I should have asked the PIC to stop until I figured out the taxi path on the chart. I made a wrong assumption in thinking that he knew where he was going (he nor I had never been to this airport before landing there the day prior). Adding to the confusion was the poor signage at the airport.

Original NASA ASRS Text

Title: Cessna Citation First Officer reported crossing a runway without clearance.

Narrative: We called for taxi and were told to standby. The Ground Controller sounded busy and a little overwhelmed. We were finally given taxi instructions to taxi via Charlie; Delta; left turn on Golf hold short of Runway XX. The PIC started to taxi out as I was busy looking at the taxi diagram to find the taxiways. I saw us approaching Runway XX and the captain proceeded to cross. I was assuming that he knew the way or at least saw the appropriate signage and knew where we were. Taxiways Delta and Golf are not labeled on the taxi diagram and I was therefore confused. As we were halfway across Runway XX; I looked down the runway and saw that an airplane had just landed and was turning off the runway. At about the same time the PIC remarked; 'I think we just crossed a runway!' We stopped on the other side of the runway and then realized there was opposite direction traffic on the taxiway and we had to do a 180. We admitted our mistake to the Ground Controller and she subsequently offered us the option to depart on Runway XX which we accepted.Looking back; I should have asked the PIC to stop until I figured out the taxi path on the chart. I made a wrong assumption in thinking that he knew where he was going (he nor I had never been to this airport before landing there the day prior). Adding to the confusion was the poor signage at the airport.

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.

Attributes
ACN	1515660
Time
Date	201801
Local Time Of Day	1201-1800
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	Citation V/Ultra/Encore (C560)
Operating Under FAR Part	Part 91
Flight Phase	Taxi
Flight Plan	IFR
Person 1
Function	Pilot Not Flying First Officer
Qualification	Flight Crew Instrument Flight Crew Multiengine Flight Crew Air Transport Pilot (ATP) Flight Crew Flight Instructor
Experience	Flight Crew Last 90 Days 60 Flight Crew Total 11200
Events
Anomaly	Conflict Ground Conflict Less Severe Deviation - Procedural Clearance Deviation - Procedural FAR Ground Incursion Runway Ground Incursion Taxiway