HomeMy WebLinkAboutITEM IV-ACITY OF * *
*AUBURN
WASHINGTON
To: Public Works Committee, Mayor Lewis
From: Pablo Para
CC: Dennis Dowdy, Dennis Selle, Rob Roscoe
Date: January 12, 2011
Re: City Speed Cushion Standard Practices
Memorandum
Engineering Division
Purpose
The purpose of this memo is to provide information to the Public Works Committee regarding
the current Speed Cushion standard practice in the City of Auburn.
Background
There are currently numerous types of vertical deflection speed control devices in use across
the country. The most common are known as "speed bumps," "speed humps," "and speed
cushions". The lengths and widths of these devices allowed in public streets can vary
significantly. The more abrupt the device is the more effective it will be in slowing traffic. The
less abrupt the device is the more it accommodates higher traffic speeds. Design guidelines
recommend using only speed humps or cushions for applications on public streets.
Several years ago, in concert with implementing the City's Traffic Calming Program, the City
chose the current Speed Cushion standard. This design with wheel gaps was selected as the
optimal standard as it satisfied the concerns of the Auburn Fire Department while having a fairly
abrupt configuration to more effectively reduce speeding. Since this standard for speed
cushions has been in use it has been effective in reducing speeds and has been favorably
accepted by the majority of neighborhoods where they have been installed. Most complaints
received regarding the devices come from individuals living outside these neighborhoods.
While other Speed Cushion standards may be adopted by the City, indications are that the
current standard supports the Council policy of "Safety Over Convenience".
Installation Requirements & Restrictions
Speed Cushions are only permitted on local residential streets with maximum speed limits of
25 MPH. Before speed cushions are recommended for installation an engineering analysis is
completed and alternative methods for mitigating speeding and cut-through are implemented.
These primary speed control methods include;
• Targeted police enforcement
• Placement of temporary speed radar trailers
• Neighborhood safety meetings.
Page 1 of 2
AUBURN *MORE THAN YOU IMAGINED
If speeding and cut through problems persist then the installation of Speed Cushions are
considered and a survey of the neighborhood is completed to determine the level of community
support.
Design Guidelines
The City's current standard for Speed Cushions is allowed within public streets. All Speed
Cushions in the city are marked and signed per MUTCD requirements which include chevron
pavement markings, warning signs and 15MPH advisory speed placards.
Attached for your reference is a drawing showing sample Speed Bump, Speed Cushion and
Speed Hump devices including the City's current Speed Cushion standard.
Page 2 of 2
AUBURN *MORE THAN YOU IMAGINED