I like all kinds of storm drain tunnels but my favorite ones are the concrete because the tunnels are usually well kept up, not slippery and they are often bright with my lights. Where I live now there are a fair amount of brick tunnels but they are not well kept up for most part. Just to be clear that I'm mostly talking about the rung condition. I know of some drains that the bricks need to be replaced or fixed because there are bricks missing or eroded, so it makes it unsafe to walk in the brick tunnels without slipping and tripping.