Date: 201908
Local time of day: 0601-1200
Location: ZZZ.Airport, US
Light: Daylight
Aircraft: B757-300
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Flight phase: Initial Climb
Airspace: Class B ZZZ
ATC / advisory: TRACON ZZZ
Second aircraft: B737 Undifferentiated or Other Model
Reporter organization: Government
Reporter function: Departure
Reporter qualification: Air Traffic Control Fully Certified
Human factors: Workload; Situational Awareness; Communication Breakdown
Anomaly: ATC Issue All Types; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Air Traffic Control
When detected: In-flight
Result: Air Traffic Control Separated Traffic
Contributing factors: Human Factors; Environment - Non Weather Related; Airspace Structure; Procedure
Primary problem: Human Factors

Narrative: I was working DR3 (Departure Radar) and climbing departures around and over the [Runway] XX final to ZZZ. I am not sure if a TM (Traffic Management Coordinator) was on position but [Initials] was working CI (Coordinator TRACON) and used to be a TM. He came over to tell me that the arrival gate was going to have too many arrivals and they'd need to cross a few over. We'd coordinated any crossovers descend to 15;000 ft.; XX arrivals would descend in my airspace to 11;000 ft. and I could use 14;000 ft. until I crossed to climb. This was working well with 4 or 5 crossovers and was very safe. It appeared the arrival controller may have been improperly fed by [Center] and next thing I know; several aircraft were reassigned a north runway to crossover and were at several different altitudes intermixed with the XX arrivals. From my perspective that created a wall of aircraft at multiple altitudes and I had no choice but to stay away. I ended up with several aircraft outside the 20 miles that I share with DR2; outside of that I have to coordinate but didn't have time to. This put me in a situation where I felt I had to use visual to assure separation and was regularly head on with arrival aircraft and making dramatic turns to get climbed above in time. After watching the replay; I did not see any losses on my part; but it was a very unsafe situation. I was told later that the arrival controller was panicking and missing turns and was unable to be coordinated with. Had I known any of this was going to happen; I would not have climbed a single aircraft and would've tunneled instead. I also would have stopped departures.This was my first position assignment after working extremely busy and for long periods of time on position the day before. I was still thinking about a safety event I'd been involved with the day before and would have liked time to file the report and get it sorted out in my mind before working again. This added to a continued feeling of being unsupported and trying to handle an unreasonably difficult situation.We desperately needed a TM on position to handle and coordinate this kind of volume. Something should have been done with [Center] to assure a proper feed or help the arrival controller in some way. When I became saturated with aircraft; it would've helped me to have the departures shut down but I did not have time to do so. This is also something a TM could've done. I would like time to do my report immediately following a safety event so I can try not to bring it into the next day. I would also like to be relieved of position immediately following a safety event; perceived or otherwise.




Synopsis: TRACON Controller reported an unsafe situation due to traffic overload.