Tiger-Striped Neck Groove Snake

Today, 'Beijing walker' left a comment to that post:

Hi, I was walking in a gorge about 2 hours north of Beijing yesterday and saw the tail end of a snake.

It was close to a stream at 1pm. I've been trying to find out what this beautiful creature is, but I can't find a photo or description that is like it.

It was dark grey/black with two wide orangey red stripes down the sides. The stripes didn't have sharp edges, just blended back into the black. I saw about 3 feet of him and judging by his thickness, I would guess he was 5 - 6 feet in length. He looked a lot like an Australian Red Bellied Black Snake, except with the red part on the sides, not the underside.

Can anyone help identify it? Thanks.

Please leave suggestions in the comments section below.