Traffic Calming

Traffic Calming is a way to promote responsible motorist behavior and safe driving speeds through street design without relying on traffic control devices such as signals, signs or police enforcement. If implemented correctly, these design strategies can reduce the number and severity of crashes, as well as noise level for adjacent land uses. The Traffic Calming strategies should be predictable and easy to understand by all road users.

NEIGHBORHOOD TRAFFIC CIRCLESource: Kimley-Horn and Associates

CÍRCULO DE TRÁFICO VECINAL

DESIGN FEATURES

Neighborhood Traffic Circles:

Neighborhood Traffic Circles are raised or delineated islands placed at intersections that reduce

EXISTING R/W (TYP) vehicle speeds by narrowing turning radii, narrowing the travel lane, and, if planted, obscure the

LÍMITE DE PROPIEDAD EXISTENTE (TÍPICO) visual corridor along the roadway. Islands can consist of raised medians or can be a combination of striping and low-cost vertical separation devices such as flexible delineators.

A mountable curb may be installed along the outer portion of the circle to accommodate larger vehicles going through the intersection (e.g., fire truck or moving van).

Traffic Circles are considered a horizontal deflection measure. Without adequate deflection, motorists can pass through the traffic circle without lowering vehicle speed.

Chicanes are a series of raised or delineated curb extensions or edge islands on alternating sides of a street forming an S-shaped travel way.

Curb extensions and edge islands should be tapered at 45 degrees.

Edge lines should be marked to designate the travel lane.

Chicanes may require drainage design, and may have a 1’ to 2’ gap from the curb to resolve drainage issues.

Chicanes:

Chicanes (Continued):

Signing may be used to alert drivers of a downstream shift in the roadway alignment.

Chicanes often require parking removal, but may allow for public space and street activation.

Raised intersections involve elevating an entire intersection to the level of the adjacent sidewalk and ramping each approach to the intersection. The raised portion is the width of the intersection and should extend 10-15’ on each leg. Signing may be added to encourage vehicles to slow down and yield to pedestrians. Tactile warning strips shall be added at edges to enable site impaired people to detect the crossing. Raised Intersections can be built with a variety of materials including asphalt, concrete or pavers. The crosswalks on each approach are also elevated as part of the treatment, to enable pedestrians to cross the road at the same level as the sidewalk. Bollards or other vertical separation device should be installed at the intersection corners to prevent vehicles from driving onto the sidewalk.

Successful implementation often involves local neighborhood participation to best identify issues and educate users on the intent of the new design. A variety of techniques may be used together and are typically most effective when spaced appropriately throughout an entire roadway length.

Raised Intersections:

OTHER CONSIDERATIONS

Source: NACTO, Urban Street Design Guide Source: NACTO, Urban Street Design Guide

REFERENCES

FHWA, Traffic Calming Countermeasures NACTO, Urban Street Design Guide APA, U.S. Traffic Calming Manual