Pilot reported a taxiway incursion onto a closed taxiway at LNC airport; due to the taxiway not identified on the airport diagram or taxi chart.

Narrative

Checked NOTAMs and saw taxiway A closed today. Nowhere on any taxi diagram were taxiways named. On approach to land on Runway 31 saw men and vehicles left of the Runway 31 working on the taxiway. I assumed they were working on taxiway A. I turned off the runway and saw D on the taxiway; so I was on taxi D; made a right turn and headed to the ramp on a parallel taxiway. Nearing the next taxiway intersection saw a low barricade on the taxiway and a letter A on the taxiway I was on. There was enough room to bypass the barricade and proceeded to the ramp. I taxied on a closed taxiway. Problem 1; the taxiway identifiers must be a secret. No where on any airport diagrams or taxi diagrams are taxiways named and listed. Please look at the taxiway diagram and tell me why no identifiers are listed. Problem 2. The barricades were very low to the ground; similar height or a parking curb. They were randomly placed on taxiways. When I turn onto taxiway D; there should have a barricade there to prevent me from going onto taxiway A. Solution. Airport charts and taxi diagrams should have names of taxiways listed.