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A new Salt Lake City program plans to revive city traffic-calming efforts after a 19-year hiatus, with a focus on walkability in local neighborhoods.
The program relaunched this year after a rash of fatal pedestrian crashes in the city. It originates from a study funded in 2019, which outlined possible solutions for the city’s most problematic roads.
The study’s final report identified 403.5 miles of roadway within Salt Lake City for possible improvements and divided those streets into 113 prioritized zones — based on crash data, speed data, demographics and community assets like schools.
Some of the highest-priority zones were identified as just west of the state Capitol, an area of Sugarhouse near Fairmont Park, and an area between Redwood Road and the Jordan River south of Interstate 80.
The program’s toolbox includes 19 different “traffic-calming treatments” that address speeding, high traffic volumes, cut-through traffic or general safety concerns, such as:
Speed lumps, humps and tables
Speed lumps, humps and tables are essentially three different versions of speed bumps.
Speed lumps are usually placed in a series across a roadway, and have designed wheel cutouts for emergency vehicles to pass through without slowing, according to the final report. The lumps are slightly less than four inches high and typically cost between $3,000-5,000 to implement.
However, a series of speed lumps is often needed to keep speeds low over a longer distance, and they can result in increased noise from vehicles accelerating. Due to their wheel cutouts, this street treatment also can be difficult to maintain.
Speed humps have a similar appearance to speed lumps, but they do not have cutouts for large vehicles and bicycles. They are typically 3-3.5 inches high and also cost between $3,000-5,000, but they can slow down emergency vehicles and also create difficulties for bicyclists.
Speed tables are flat-topped speed humps approximately 22 feet long, which is typically long enough for the entire wheelbase of a passenger car to rest on top. Their ramps are more gently sloped than speed lumps, so they can be placed on streets that allow higher speeds than those allowed for speed lumps and humps.
Speed tables typically cost $20,000-$30,000 to implement, but aren’t as effective in reducing speeds as speed lumps.
Raised crosswalks cost about $20,000-$30,000 to implement, according to the report. These crosswalks are more visible to approaching drivers, and include a speed table that enhances speed reduction.
This treatment is effective in reducing speeds, but not as much as speed lumps, the report states. Raised crosswalks also improve safety for both vehicles and pedestrians, but can be harder to maintain and result in increased noise.
Speed feedback signs
These digital signs are commonly used in school zones to measure each approaching vehicle’s speed. The signs relay real-time speeds to drivers and are typically mounted on or near a speed limit sign.
These signs typically cost $7,000-$15,000 to implement, according to the report, and do not interfere with speeds for emergency vehicles. Speed and count data can be recorded on these signs, which are often solar powered.
However, the slow-down effect of these signs may not be permanent and the signs can only be used for one traffic direction, the report states.
Pedestrian refuge islands
These are raised islands placed in the middle of a roadway where traffic circulates around them. They help increase pedestrian safety, can be aesthetically pleasing and also reduce speeds.
These islands typically cost about $10,000-$20,000 to implement, but their effectiveness can be limited in the absence of speed deflection treatments, the report states.
Roundabouts typically cost $150,000 or more to implement, and are typically used on higher volume streets to allocate right-of-way competing movements.
They require traffic to circulate counterclockwise around a center island, often substituting for traffic signals. The report states that roundabouts might be most appropriate for new developments or redeveloped areas, due to the large amount of required right-of-way and construction costs.
Roundabouts are safer compared to traffic signals and minimize traffic lines at intersections. They also are less expensive to operate than traffic lights and can be aesthetically pleasing to neighborhoods.
However, roundabouts may require major construction and limit pedestrian crossings compared to traffic lights. They may also present additional obstacles to visually-impaired pedestrians.
When will these be constructed?
Quick-action pilot projects could start as soon as this fall, but an overhaul may not begin until late 2024.
“There’ll be outreach and engagement and development of the plan and the design neighborhood by neighborhood, followed by bidding it out and finding contractors that can build it for us — often, that process takes two years,” Jon Larsen, the city’s director of transportation, said .
Across the board, implementation is dependent on future funding, which Larsen said was requested in this year’s capital improvement budget. Once the program has its team on board, they’ll begin prioritizing roadways to start on with guidance from the city council.
“I know that sounds like a really long time to people; we’re hoping to find ways to speed up that process, and especially having more staff, I feel confident we will be able to,” Larsen said.