vision2020@moscow.com: Calming Traffic, Research (fwd)
Calming Traffic, Research (fwd)
Bill London (london@wsunix.wsu.edu)
Mon, 11 Aug 1997 12:39:32 -0700 (PDT)
Here's a reprint of a report on the success of the traffic calming program
in Seattle. The traffic calming devices they use there (traffic circles
at intersections) are well-supported by the neighbors, reduce accidents,
and calm traffic effectively.
While the Polk STreet project doesn't use traffic circles (since
there are no residential intersections involved), I believe similar
results will occur with the curb extensions planned for this street.
BL
>
>TRAFFIC CIRCLES REPLACE STOP SIGNS !!!!!
>
>James Mundell, Senior Traffic Engineer for the City of Seattle (600
>Fourth
>Ave, #410, Seattle, WA 98104-1879; Tel: 206-684-0814; Fax:
>206-470-6934)
>presented a paper this month at the Institute of Transportation
>Engineer's
>1997 Annual Meeting, "Neighborhood Traffic Calming: Seattle's
>Traffic Circle
>Program" which indicates that their program is extremely successful.
>Highlight include:
>
>* 600+ traffic circles have been constructed and the city recieves
>requests
>for about 700 more each year (they can only fund about 30).
>
>* During the 1991 to 1994 period, 119 traffic circles were
>constructed. A
>before and after comparision of these streets indicates an amazing
>reduciton
>in both accidents (187 down to 11) and accident injuries (153 to 1),
>despite
>previous trends of steady increases in accidents! Accident rates
>have
>remained at very low levels in subsiquent years.
>
>* Four-way stop signs do not have the same effect on traffic
>reduction.
>
>* Only two circles have been removed out of more than 600
>installed, and
>none have been removed during the last twelve years. Residents are
>guaranteed that the city will remove a traffic circle, after
>construction,
>if requested by 60% of households within a block radius. Resident
>surveys
>indicate 80-90% support for traffic circles after they are
>installed.
>
>--snip--
>
>Many of the intersections with circles previously had four-way
>signs. Of
>four such interesections studied there was an average 90% reduction
>in
>annual accidents (from 49 to 5) and a 97% reduction in injuries (38
>to 1)
>after circle installation.
>
>Mundell states, "A common question that is asked, relates to the
>cost
>effectiveness of traffic circles, because they are much more
>expensive than
>installing stop signs. Traffic circles are sometimes viewed as an
>esthetic
>improvement and that intersections should be made safer by
>installing yield
>or stop signs at considerably less expense. The significant
>reduction in
>accident attributable to traffic circles demonstrates that they pay
>for
>themselves many times over in reduced accident costs in just the
>first year."
>
>Traffic engineers tell me that the speed control impact of stop
>signs
>appears to decline over time, particularly if there is no
>enforcement.
>However, this does not appear to occur with physical structures such
>as
>traffic circles.
>
>Traffic circles also appear to have aesthetic benefits (everybody
>loves a
>planter) and I suspect that they tend to increase nearby residential
>property values (a number of studies indicate that traffic
>management in
>residential areas increases property values). City of Seattle
>surveys
>indicate that 80-90% of residents approve of the circles after they
>are
>installed.
>
>Anybody interested in traffic calming may want to obtain the current
>issues
>of the ITE Journal, both of which focus on traffic calming. The July
>issue
>has articles on "ITE Traffic Calming Definition" plus surveys of
>traffic
>calming activities in Australia, Canada, Europe and in
>neotraditional
>
>neighborhood design. The August issue is supposed to include more
>articles
>on the subject, but I haven't seen it yet.
>
>Some of you may also be interested in my own paper, "Evaluating
>Traffic
>Calming Benefits, Costs and Equity Impacts, available from our
>Institute. It
>summarizes the literature on various impacts of traffic calming, and
>develops a framework for evaluating the benefits and costs in a
>particular
>situation.
>
>
>Sincerely,
>
>Todd Litman, Director
>Victoria Transport Policy Institute
>"Efficiency - Equity - Clarity"
>1250 Rudlin Street
>Victoria, BC, V8V 3R7, Canada
>Phone & Fax: (250) 360-1560
>E-mail: litman@islandnet.com
>Website: http://www.islandnet.com/~litman
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