SAN FRANCISCO (KCBS)— The four-block stretch of San Francisco’s Market Street from 7th to 11th streets is the dirtiest commercial corridor according to a new survey by city controller’s office.

The 2014 Street and Sidewalk Maintenance Standards report may be stating the obvious and not many who’ve encountered the area would be surprised. Nonetheless, 10 inspectors canvassed the city’s streets to survey the sights and the sometimes less-than-savory smells.

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The juxtaposition of this troubled corridor with the millions of dollars being invested in the influx of tech companies relocating and being attracted to the area such as Uber, Twitter, and ZenDesk right in the middle of things, and Union Square just a couple blocks to the west, is stark to say the least.

Despite the efforts to slowly revitalize and make this the hip new neighborhood, the survey still ranks this area at the bottom as some of the worst streets to walk around.

Department of Public Works Spokeswoman Rachel Gordon said crews of street sweepers and green machines are out at 4:30 a.m. to clean up, but then about an hour later, things look dirty again.

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When you get off at the Powell Street BART Station and head west towards the water, you’ll see some of the fanciest stores and hotels in the United States. It’s booming. If you walk the opposite direction it’s another story. Here’s why: years ago for every fancy store, shopping development and high-rise office built, there was a deal that said they would have to kick in money for non-profit and low-end housing. These developments went to what we all know as the Tenderloin.

It’s become known as a haven (for lack of a better term) for homeless and it’s right smack dab in the middle of downtown. There have been more recent community benefits districts established with this most recent tech wave.

It’s interesting to see how the haves and have nots are co-existing, practically on top of one another, now that we’re a few years into this tech boom. You have Twitter in a high-rise above, but meanwhile, things down below on the street level can get pretty messy.

Earlier this month we reported that Twitter headquarters was waiting for the city’s approval to build a sky bridge that would connect its main headquarters to one of their adjacent buildings. The reason they gave was that it would make things more efficient for their employees to go from building to building this way rather than to have to use an elevator and leave the building.

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I have a feeling not all of the employees exactly feel safe or are impressed with the Mid-Market grittiness that most long-time San Francisco residents have come to accept. In some ways Mid-Market is the area that time forgot and it’s going to take a lot of time for it to change.