Tunnel Reverberation

Morning foot traffic above sent low tremors through the tiled underpass walls. I stepped off the concrete ledge and marched past the sealed inspection hatch toward the stairs. Wedged under the lowest steel handrail bracket was an abandoned green aluminum carabiner, scuffed around its gate. I didn't let it sit idle. Gripping the cold curved spine with both hands, I struck it hard against the tubular handrail. Cling-tock. The metallic ring bounced off the white glazed subway tiles, echoing down the empty curved passage in a sharp, crisp double pulse. The acoustic response is tight. Tunnel line active.