Hi Selena could you please explain what road diet is.

Is the traffic?.

There are several publications by ITE - Institute of Transportation Engineers, USA on traffic capacity, analysis etc.

best regards

Ravi

A road diet reduces the lanes on a street. The "classic" road diet takes a street with 4 lanes - 2 travel lanes in each direction - and restripes the street to have 1 travel lane in each direction and a center median for left hand turns.

This treatment works on streets with excess capacity that isn't being used, which is measured by average daily traffic (ADT). A good candidate for a 4 to 3 lanes conversion will have an ADT of 20,000 cars or less per day.

The goals with this treatment is to reduce travel speeds and repurpose the extra space on a roadway for other uses, like adding bike lane or sidewalks. This tool is a favorite of the Vision Zero traffic safety movement.

More information here: https://safety.fhwa.dot.gov/road_diets/guidance/info_guide/

Have you reviewed the following one?

An Evaluation of “Road Diet” Projects on Five Lane and Larger Roadways by Jack Cebe (2016)

https://planning-org-uploaded-media.s3.amazonaws.com/document/An-Evaluation-of-Road-Diet-Projects-on-Five-Lane-and-Larger-Roadways.pdf

Yes, that's the only article I've found.

Could you please explain what Road Diets is?

Tengfei Wu I answered your question earlier in this thread.

It would be great to understand the context. Based on your peak volume, it seems the road might be at capacity, which makes it challenging to reduce the number of lanes (or implement other capacity reduction elements) without introducing other impacts to congestion. If the goal is focused more on a change to the center lane (assume a continuous dual left turn lane?) it might be helpful to look for papers related to access management. Access management often introduces new median conditions that restrict left turns, removes right turn lanes, closes entrances, etc.

This is in reference to the Great Streets Venice Blvd pilot project implemented by the City of Los Angeles. The City's website for this project is www.veniceblvdmarvista.org. The community's website is restoreVeniceBlvd.com (that site needs to be updated.)

If you do a Google search, you will see that this project has been very controversial. Taking a travel lane away in each direction has created gridlock, cut through traffic and delays for emergency responders. Small businesses are reporting a decrease in customers because parking was removed and customers are avoiding the area because the new street configuration is confusing.

A protected bike lane was also added, replacing the previous bike lane next to parking. There are 43 driveways and 10 unsignalized intersections in this stretch of Venice Blvd, aka unmitigated conflict points. There have been many accidents between bikes and cars in the new protected bike lane. There are also a growing number of bike versus pedestrian accidents, since the parking was moved away from the curb to the other side of the bike lane and now drivers and passengers have to walk through the bike lane to get to and from their cars.

For these reasons, the community feels that Venice Blvd was not an appropriate candidate for a road diet. This is why I am looking for any published guidance about putting a road diet on a street with 5 or more lanes and what alternatives there are if the road doesn't meet the criteria for a road diet.

Also, Venice Blvd has a concrete median down the middle of the street which can not be removed. There are left hand turn lanes, but they do not go down the length of the street. This is a remnant of the days when a Red Car trolley used to travel down Venice Blvd. from downtown to Venice Beach. Utilities have since been run down the middle of the street and, in some points, the street is actually not level.

I hope this information helps give my question more of a context.

Ah, I see - based on your original question I was going to recommend against a road diet for your case, but it seems like it's been done and your topic makes sense. I know FHWA has a good series of case studies: https://safety.fhwa.dot.gov/road_diets/case_studies/

The case studies acknowledge the trade-offs with some road diet projects, often congestion, delays, or increased accidents of a certain category. I've been investigating relationships of capacity and demand, so the Highway Capacity Manual might have some notes as well. It seems that the road was already at capacity, so reducing capacity wouldn't have been recommended unless the City also invested in alternate modes of transportation, new routes, or other ways to mitigate.

Interested to hear what you find on this.