NYMTC Regional Pedestrian Safety Study - New York Metropolitan ...

crossing exists, to raise the awareness of drivers that a pedestrian crossing is in place, and to
make pedestrians in the crosswalk more visible to drivers. Raised crosswalks also aid in the
reduction of speeds. If the level of the entire intersection is raised it is referred to as a raised
intersection. A study of effectiveness found that there were significant reductions in vehicle
speed at two out of three locations. It also found that there was an increase from 31 percent to 79
percent of motorists stopping for pedestrians at a raised crosswalk with an overhead flasher, but
an insignificant increase at a similar intersection without a flasher. (Huang and Cynecki, 2001)
Chicanes: Chicanes are roadway curb extensions that usually alternate from the one side of the
street to the next. Their main objective is to force drivers to reduce speed by following an S-type
curve vehicle path. One form of chicane is alternate parking (diagonal or parallel). Their main
advantage over speed humps is a reduction of noise.
Chokers (Pinch Points, Midblock Narrowings, Midblock Yield Points, Constrictions): Chokers
are also curb extensions that are created mid-block of a roadway. These curb extensions can take
various forms such as: Curb extensions at both sides of the street – main effect is reduction of
speed at both directions; Curb extensions at both sides of the street plus crosswalk – main effect
is reduction of speed plus a “safe” pedestrian crossing; Curb extensions that effectively leave
only one lane crossing such that vehicles proceed one at a time alternating for each direction –
severe reduction in speed up to a complete halt.
Roadway Lane Width: Roadway lane width is listed separately as a traffic calming control
measure as it could be used by itself or in combination with roadway narrowings. The theory is
that lane narrowing “forces” the driver to become more attentive, which leads to reduced speeds
and crashes. Lane widths of 12 feet and above tend to make the drivers less attentive since they
worry less about the vehicles next to them, resulting in an increased probability of crashes. It is
noted that for two-lane highways this implementation may not be effective since the narrowing
usually is only visual rather than actual – the driver does not feel any danger from his/her right
side so he may simply drive partially on the shoulder. A comprehensive study related to traffic
fatalities and injuries by Noland (2002) notes that "as more arterial and collector lane widths are
increased up to 12 ft or more, traffic fatalities and injuries increase” and concludes that roadways
with lanes less than 11 feet wide are safer. The study was based on 14 years of data from FHWA
covering all 50 states up to 1996.
Therefore, the lane width may be used as a traffic calming measure to reduce fatalities and
injuries. Lane width narrowing should be properly designed such that it indeed forces the drivers
to slow down and become more alert. A previous study by FHWA where only visual narrowing
was attempted had shown there was no effect on traffic speeds. Under those conditions, the lane
width was indeed narrowed, however wider shoulder widths negated any effect on traffic speeds.
Concluding Comments of Traffic Calming
The choice of specific traffic calming measures should take into consideration the requirements
of the particular location, including the character of the area, the type and volume of traffic, and
the needs of emergency vehicles. Several variations of traffic calming measures can be observed
throughout the country, including comprehensive traffic calming strategies that combine several
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