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Traffic Calming Guidance Resources

Based on engineering judgment, traffic calming strategies should be considered whenever there is a need to reduce vehicle speeds and/or traffic volumes on a roadway or roadway network. These elements are prepared for Caltrans for use on the California State Highway System and it is not a substitute for engineering knowledge, experience, or judgment. The traffic calming measure can be implemented separately or be used in conjunction with other calming measures.

Each traffic calming measure belongs to one of six categories: Signing and Markings, Physical Intersection Modifications, Roadway Narrowing, Vertical Roadway Elements, Physical Roadway Segment Modifications, and Others.

For more information, email Safety Programs.

Resources

Traffic Calming Guidance Elements

SIGNINGS AND MARKINGS
Vehicle Speed Feedback Sign
 Image of a traveled roadway with a speed feedback sign showing posted speed limit and digital feedback about drivers speed
Description: Speed Feedback Signs (SFS), also known as Dynamic Speed Displays, provide drivers feedback about their speed, while reminding drivers of the posted speed limit.
Standard Plans: Roadside Signs RS1 | RS2 | RS3 | RS4 | RS5 | RS6
CA MUTCD: Section 2B.13 Figure 2C-1 (does not indicate maximum posted speed limits for this countermeasure)
Other Guidance: FHWA Spotlighting Speed Feedback Signs
Speed Reduction Markings
 Image of car in a traveled roadway with speed reduction markings, transverse pavement markings placed with progressively reduced spacing to create the perception of increased speed
Description: Speed Reduction Markins, also known as Optical Speed Bars, are transverse pavement markings placed with progressively reduced spacing on both edges of the traveled way to create the perception of increased speed. This illusion encourages drivers to slow down as they pass by the markings.
CA MUTCD: Section 3B.15, Figure 3B-28 | 3B.22
Other Guidance: FHWA Low-Cost Treatments for Horizontal Curve Safety 2016, Chapter 3
In-Street Pedestrian Crossing Signs
 Image of roadway with in-street pedestrian crossing markings and signs to remind road users of laws regarding right-of-way at an unsignalized pedestrian crossing
Description: In-street pedestrian crossing signs are placed within a roadway, either between travel lanes or in a median. The sign may be used to remind road users of laws regarding right-of-way at an unsignalized pedestrian crossing.
Standard Plans: Signs/Delineators A73A | A73C
CA MUTCD: Section 2B.12, Figure 2B-1, Table 2B-1 | Section 7B.12, Figure 7B-6
Other Guidance: FHWA Proven Safety Countermeasures - Crosswalk Visibility Enhancements
Crosswalk Enhancements
 Image of a car approaching a crosswalk enhancements that includes a high-visibility crosswalk markings and advance stop/yield/pedestrian crossing markings and signs
Description: Crosswalk enhancements include high-visibility crosswalk markings and marking patterns, improved lighting, advance stop/yield/pedestrian crossing markings and signs, parking restrictions, curb extensions, raised crosswalks, rectangular beacons (RRFB), and pedestrian hybrid beacons.
Standard Plans: Crosswalks A24F | Roadside Signs RS1 | RS2 | RS3 | RS4 | RS5 | RS6 | APS Push Buttons ES-5C
CA MUTCD: Section 2B | 3B.16 | 3B.18 | Chapters 4E | 4F | 4L
Other Guidance: FHWA Field Guide for Selecting Countermeasures at Uncontrolled Pedestrian Crossing Locations | FHWA Guide for Improving Pedestrian Safety at Uncontrolled Crossing Locations | FHWA Proven Safety Countermeasures - Crosswalk Visibility Enhancements
Pedestrian Hybrid Beacons
 Image of roadway with pedestrian hybrid beacons that are pedestrian-activated overhead signals with two red lenses above a single yellow lens
Description: Pedestrian hybrid beacons (RHBs) are pedestrian-activated overhead signals consisting of two red lenses above a single yellow lens. The lenses remain "dark" until a pedestrian pushes the call button to activate the beacon, which then initiates a yellow to red lighting sequence that directs motorists to slow and come to a stop.
Standard Plans: Mounting ES-4E
Standard Specs: 87-8
CA MUTCD: Chapter 4F
Other Guidance: FHWA Pedestrian Hybrid Beacon Guide | FHWA Proven Safety Countermeasures - Pedestrian Hybrid Beacons
Flashing Beacons
Image of several motorists being warned with flashing beacons that use repeated flashing lights to warn of a potential hazard or an upcoming change in the road conditions
Description: Flashing beacons use repeated flashing lights to warn motorists of a potential hazard. They are used to draw motorists' attention to a sign informing them of an upcoming change in the road conditions that could include unseen intersections, schools, curves, or other hazards.
Standard Plans: Flashing Beacon ES-7J | ES-7K | ES-7L
Standard Specs: 87-7
CA MUTCD: Chapter 4L
Other Guidance: FHWA Low-Cost Treatments for Horizontal Curve Safety 2016, Chapter 4

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PHYSICAL INTERSECTION MODIFICATIONS
Roundabouts
 
Description: A roundabout is a form of circular intersection in which traffic travels counterclockwise around a central island and entering traffic must yield to the circulating traffic.
HDM: Chapter 400, Index 405.10
CA MUTCD: Chapters 2B | 2C | 3C | 6H | 9C
Caltrans DIB: 94
Other Guidance: Caltrans Proven Safety Countermeasures Roundabouts | FHWA Traffic Calming ePrimer (3.09) | FHWA Proven Safety Countermeasures | Traffic Operations Policy Directive #13-02
Full Closure
Image of a typical full closure intersection that improves safety by reducing intersection conflict point and cut-through traffic 
Description: Typical full closure implementation can help improve safety by reducing intersection conflict points and cut-through traffic.
Standard Plans: Ramp Closure T14
Caltrans DIB: 93 
Other Guidance: FHWA Traffic Calming ePrimer (3.22)
Intersection Barrier
 Image of an intersection barrier used to limit left-turn movement through an intersection with a raised island forcing drivers to reduce approach speed
Description: An intersection barrier can be used to limit left-turn movements through an intersection. A fixed barrier such as a curb, raised island, or planter limits vehicle movements through the intersection, forcing drivers to reduce approach speeds.
Standard Plans: Curbs A87A
HDM: Topic 404
Other Guidance: FHWA Traffic Calming ePrimer (3.24) | ITE Traffic Calming Facts Sheets - Median Barrier
Partial Closure/Semi-Diverter
 Image of a typical partial closure implementation at an intersection that improves safety by reducing intersection conflict points and cut-through traffic with a planter
Description: Typical partial closure implementation can help improve safety by reducing intersection conflict points and cut-through traffic.
Standard Plans: Traffic Control T13A | T13B
Caltrans DIB: 93
Other Guidance: FHWA Traffic Calming ePrimer (3.23)
Right-In, Right-Out
 Imagery of a typical right-in, right-out to help reduce intersection conflict points, cut-through traffic, and restricting movements that have a higher likelihood of more severe injury crashes
Description: Typical right-in, right-out implementation can help improve safety by reducing intersection conflict points, cut-through traffic, and restricting movements that have a higher likelihood of more severe injury crashes.
HDM: Topic 404
Caltrans DIB: 93
Other Guidance: FHWA Traffic Calming ePrimer (3.24)| HCM 7th Edition Chapters 4, 15, 25, 35 | ITE Traffic Calming Fact Sheet - Forced Turn Island
Tee-up Intersection and Reduce Corner Radii
Image of tee-up intersection or corner radii directly impacts vehicle turning speeds and pedestrian crossing distances
Description: Corner radii directly impacts vehicle turning speeds and pedestrian crossing distances. Minimizing the size of a corner radius is critical to creating compact intersections with safe turning speeds.
HDM: Chapter 400
Caltrans DIB: 94
Other Guidance: Caltrans Complete Intersections 2010 | NACTO Urban Street Design Guide, Corner Radii

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ROADWAY NARROWING
Road Diet
Image of a typical road diets where roadway treatments reduce the number of travel lanes and/or lane widths to address transportation deficiences. 
Description: Typical road diets include roadway treatments that reduce the number of travel lanes and/or lane widths in order to address transportation deficiencies. Road diet allows reclaimed space to be allocated for other uses, such as bike lanes, sidewalks, bus islands and shelters, bus lanes, landscaping, pedestrian refuge islands, turn lanes, or parking.
HDM: Chapter 300
Caltrans DIB: 94
Other Guidance: FHWA Traffic Calming ePrimer (3.20) | FHWA Road Diet Policies
Neckdowns/Chokers
Image of a choker, a horizontal extension of the curb at a midblock of a street which gives a narrower roadbed section 
Description: A choker is a horizontal extension of the curb at a midblock of a street resulting in a narrower roadbed section. Other terms for choker include neckdown, midblock narrowing, midblock yield point, pinch point, constriction, or edge island. If the choker is marked with a crosswalk, it is sometimes called a safe cross.
HDM: Topic 303, Index 303.4(1)
Caltrans DIB: 93 | 94
Other Guidance: FHWA Traffic Calming ePrimer (3.17)
Curb Extension/Bulbouts
Image of an intersection that has bulbouts curb extensions that shorten the crossing distance and provide more area and visibility for pedestrians 
Description: Bulbouts are curb extensions that shorten the crossing distance and provides more area and visibility for pedestrians.
Standard Plans: Curbs A87A | Curb Ramp A88A | Temp Ped Ramp T33 | Temp Ped Curb Ramp T34
HDM: Indexes 303.4 | 404.4
Caltrans DIB: 93 | 94
Other Guidance: FHWA Traffic Calming ePrimer (3.16)
On-Street Parking
Imagery of on-street parking tha can assist in lower operating speeds by constricting driver experience with increased side friction 
Description: On-street parking can assist in achieving lower operating speeds by constricting driver experience with increased side friction.
Standard Plans: Accessible Parking On-Street A90B
HDM: Chapter 300
CA MUTCD: Sections 2B.46 | 2B.47 | 2B.48 | 3B.19
Caltrans DIB: 82-06
Other Guidance: AASHTO Highway Safety Manual | FHWA Traffic Calming ePrimer (3.19) | ITE Traffic Calming Fact Sheet - On-Street Parking
Raised Median Island/Traffic Island
Image of traffic islands and raised median islands that introduce a curb adjacent to vehicles and has the effect of slowing vehicles 
Description: Traffic islands are typically used for channelization but could also be used for traffic calming, since it introduces a curb adjacent to vehicles and has the effect of slowing vehicles. Pedestrian refuge islands and raised median islands are commonly used together.
Standard Plans: Island passageway A88B
HDM: Topic 405.4, Table 405.4 | Topic 904
CA MUTCD: Sections 2C.63 | 2C.64 | 2C.66 | Chapter 3I
Caltrans DIB: 82-06 | 93 | 94
Other Guidance: FHWA Traffic Calming ePrimer (3.18)

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VERTICAL ROADWAY ELEMENTS
Speed Hump
 Image of a speed hump an elongated mound in the roadway pavement surface extending across the travel way at a right angle to the traffic flow
Description: A speed hump is an elongated mound in the roadway pavement surface extending across the travel way at a right angle to the traffic flow.
CA MUTCD: Sections 2C.29 | 3B.25 | 3B.26 | Figure 3B-30
Caltrans DIB: 93
Other Guidance: FHWA Traffic Calming ePrimer (3.10) | ITE Updated Guidelines for the Design and Application of Speed Humps
Speed Cushions
Image of a speed consisting of two or more raised areas placed laterally across a roadbed with gaps that enable a wide truck to pass through the feature without any vertical deflection 
Description: A speed cushion consists of two or more raised areas placed laterally across a roadbed. A speed cushion has gaps between the raised areas to enable a vehicle with a wide track to pass through the feature without any vertical deflection.
CA MUTCD: Sections 2C.29 | 3B.25 | 3B.26 | Figure 3B-30
Caltrans DIB: 93
Other Guidance: FHWA Traffic Calming ePrimer (3.11) | ITE Updated Guidelines for the Design and Application of Speed Humps
Speed Table/Raised Crosswalk
Image of a speed table that runs transverse to the direction of traffic with a ramp up followed by a flat section and ramp down 
Description: A speed table is a vertical traffic calming device, similar to a speed hump, that runs transverse to the direction of traffic. Speed tables are longer than speed humps, typically having a ramp up of approximately six feet followed by a 10 feet minimum flat section and a ramp down of six feet.
CA MUTCD: Sections 2C.29 | 3B.18 | 3B.25 | 3B.26 | Figure 3B-30
Caltrans DIB: 82-06 | 93
Other Guidance: FHWA Traffic Calming ePrimer (3.12 | 3.14) | ITE Traffic Calming Fact Sheet - Speed Table/Raised Crosswalks | NACTO Urban Street Design Guide - Speed Table
Offset Speed Table
 Image of an offset speed table that is a speed tale spit in half down the street centerline with longitudinal separation between the two halves, which allows emergency vehicles to pass through with minimal delay
Description: An offset speed table provides the speed limiting benefits of a speed table, while allowing emergency vehicles to pass through with minimal delay. An offset speed table is a speed table split in half down the street centerline with longitudinal separation between the two halves.
CA MUTCD: Sections 2C.29 | 3B.18 | 3B.25 | 3B.26 | Figure 3B-30
Other Guidance: FHWA Traffic Calming ePrimer (3.13) | ITE Traffic Calming Fact Sheet - Speed Tables/Raised Crosswalks | NACTO, ITE Offset Speed Tables for Reduced Emergency Response Delay
Transverse Rumble Strips
Image of transverse rumble strips that have raised or grooved patterns perpendicular to the direction of travel in the roadway travel lane providing an audible and tactile warning of a downstream decision point 
Description: Transverse rumble strips are raised or grooved patterns installed perpendicular to the direction of travel in the roadway travel lane. They provide an audible and tactile warning of a downstream decision point.
Standard Plans: Portable Transverse Rumble Strip T13
CA MUTCD: Sections 3J.02 | 6F.87
Other Guidance: FHWA Factors Influencing Operating Speeds and Safety on Rural and Suburban Roads
Raised Intersection
 Image of a speed consisting of two or more raised areas placed laterally across a roadbed with gaps that enable a wide truck to pass through the feature without any vertical deflection
Description: A raised intersection is a vertical traffic calming device that raises the entirety of an intersection by three to four inches. The ramp sections of the intersection are approximately six feet in length with no greater than a 5% slope.
Caltrans DIB: 82-06
Other Guidance: FHWA Traffic Calming ePrimer (3.15) | ITE Traffic Calming Fact Sheet - Raised Intersection | NACTO Urban Street Design Guide - Raised Intersection

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PHYSICAL ROADWAY SEGMENT MODIFICATIONS
Lateral Shifts
 Image of a lateral shift, a realignment of an otherwise straight street that causes travel lanes to shift used to reduce motor vehicle speed along the street with a median island
Description: A lateral shift is a realignment of an otherwise straight street that causes travel lanes to shift. The primary purpose of a lateral shift is to reduce motor vehicle speed along the street. A typical lateral shift separates opposing traffic through the shift with the aid of a median island.
CA MUTCD: Sections 6C.08
Caltrans DIB: 93
Other Guidance: FHWA Traffic Calming ePrimer (3.4) | ITE Traffic Calming Fact Sheet - Lateral Shift
Chicanes
Image of chicanes, a series of narrowing elements that alternate from one side of the street to the other, forming an S-shape, curvilinear roadway alignment 
Description: Chicanes are a series of narrowing elements, such as curb extensions, that alternate from one side of the street to the other, forming an S-shaped, curvilinear roadway alignment. They introduce horizontal curvature to the road, breaking up the "runway effect" of wide and straight streets.
HDM: Topic 303.4 | 404
Caltrans DIB: 93
Other Guidance: FHWA Traffic Calming ePrimer (3.5) | ITE Traffic Calming Fact Sheet - Chicane

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OTHERS
Street Trees and Landscaping
 Imagery of street trees and landscaping that contribute to a reduction in the rate of crashes with the perception of a narrowing roadway, where a driver is more likely to encounter pedestrians, bicyclists, and cross-traffic
Description: Street trees and landscaping can contribute to a reduction in the rate of crashes. This effect is often attributed to a perceived narrowing of the roadway, a sense of rhythm and human scale created by framing the street, and the perception that the driver is in a place where they are more likely to encounter pedestrians, bicyclists, and cross-traffic.
HDM: Indexes 201 | 309 | 405.1 | 901.2 | 904.3 | 904.5
Caltrans DIB: 82-06
Other Guidance: Caltrans Encroachment Permits Manual Section 506 | FHWA Speed Management ePrimer | NCHRP Report 737 - Design Guidance for High=Speed to Low-Speed Transition Zones for Rural Highways
In-Roadway Lights
 Image of in-roadway lights installed in the roadway surface to warn road users that they are approaching a condition on or adjacent to the roadway
Description: In-Roadway Lights (IRWLs) are a special type of highway traffic signal installed in the roadway surface to warn road users that they are approaching a condition on or adjacent to the roadway.
CA MUTCD: Chapter 4N

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Proven Safety Countermeasures

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