Maintenance for old raspberry bush

On our property there’s an old raspberry bush area, about 10ft x 10ft. Obviously harvesting them has been impossible they are just a huge bushy.. Bush. Really densely grown and there are old dead canes standing up as they have been just neglected for years.

I was thinking that I would make the raspberry bush area kind of a keyhole shape so that I could dive in to harvest. Any reason why not to..?

How should I proceed? The snow is still well in the ground here in Finland. I would start by cutting down the old dead canes I guess.. Or should that be done later when the second year canes start doing their thing so that I wont accidentally cut them too?

I will come back with photos later today!

I would start by breaking it into 2 foot wide strips in your thinking.  Strips 1,3,5 are the keep strips, 2 and 4 are the move/remove to plant elsewhere.  This will give you 3 rows with narrow paths between.(ideally would like larger rows so alternate would be 2 rows with a wider path between.  Next ideally you want to know if yours bear first year or second in your climate.  Does your fruiting take place on second year wood or first year wood?  If you don't know I would simply cut all dead wood out and trim the living wood back to about 2 feet and watch to see what happens the first year.  If the bark is peeled or peeling that is dead wood.  Then feel the rest.  Living wood flexes different and feels different in you hand to identify which stems are living wood.  

Thank you for the advice!

I went to see what’s up in there and well.. Not much! I’m guessing that the couple of heavy snows this winter snapped many of the canes.. We just had about 15 inches snow a week or so ago so everything that has snapped before that is under the snow.

The area is also wider than I remembered.. But rows would be probably the wisest thing to do. I also did feel the canes and the dead ones were easy to spot.

Oh and I think they fruit on the second year. We’ll see what happens when the snows melt. A good time for the maintenance if most of the canes have snapped broken, less to feel bad about taking down good plants! Here’s a picture: