Domain authority can have a big influence on page authority.  Its not a direct correlation, because page authority depends on a lot of different inputs on a page level (internal links, external links, information architecture, perceived value).  But just because a site have good DA doesn't mean that all internal pages get a nice PA.

Depending on the value of those three backlinks, three could be all you need to boost a PA.

1. File names- always use the hyphen.

2. Alt Text - use spaces and normal word structure.  Ryan is correct on the technical intent behind the alt tag, but it can also be a good SEO tool, and you should treat those as exact phrase keywords.  So nobody is searching for "city-bikes", they are searching for "city bikes".  The alt tag should be what the user will put into google.

I second this opinion.  folders are the best way to go here.

I second all the comments below.  That should give you enough professional consensus in this arena to head in the right direction.   Redirect with teh keywords, and this will have the best long-term results.

As for Google parsing keywords out of urls or anything else...  You will need to remember that for the most part google ignores special characters and parameters in both content and urls.  It doesnt matter if the url is in a link or the actual url bar up top, google will treat it the same.  Google knows its a url string, and applies its "url parsing logic" to it.  So it only makes sense that a full url link would be parsed, just the same way your website url is parsed because it includes the keywords.   Its the same logic.

Technically this just creates a link farm, of which the search engines can easily draw the connections.  They know that you, linking to them, and them linking to these other sites are all connected.  Give them 6 months and they will have all the lines drawn between your dots

Not the best long term strategy.... but I also know that this still works in the real world (so I've heard.....:)  Short term you can get some valuable link juice there, and will probably see some benefits.  But know that you could get smacked down one day.

I am starting a Google doc today, and will start populating directory links with information.  Anyone that wants to help put the new list together, shoot me a personal message from my profile here and i will share the doc with you!

I will probably start a new Q&A post specifically for this so we can collaborate and have a dedicated section- so keep your eyes out and join the discussion.

Along those same lines, does anyone else know of any good services that will provide physical business addresses in certain locations?  I know of some virtual office providers, but only found ones that do major cities, not smaller ones.

I like the idea of crowd sourcing the directory list.   I agree with the "Dont take it down".  Lets all be honest here... we mostly use the directory listings for one-way link building, and whether it actually sends traffic or not- dont really care.  I know if it did send traffic, it would be crappy traffic.

I would be more than happy to contribute to a PRO generated list, only available to PRO members.  That would be a nice perk, and a great value add.  i think we all want to know what directories work for each other   This is probably the only place i would fee ok sharing.

Cant go the PO box route.  They are cracking down on local listings.  You need a physical address. Its not a problem to share the address if you have different suite # or something in.  There are also some companies out there that you can pay to give you a virtual office address in major cities, and you could technically use that.  Remember that you will need to verify the listing, and sometimes Google will not let you do it via the phone, they will only do the postcard route, so you will need to monitor the mail to that location.