Design Criteria Memorandum UNION STREET RAILROAD BRIDGE (Trail Connection Project)

Design Criteria
Memorandum
for
UNION STREET RAILROAD BRIDGE
(Trail Connection Project)
Key No. 11085
ODOT, Region 2 Local Agency On-Call
ATA 23456 WOC 1
City of Salem, Urban Development
HDR Project No. 007337: 30289
October, 2005
Vigil-Agrimis, Inc.
819 SE Morrison St., Suite 310
Portland, OR 97214
1001 SW 5th Ave., Suite 1800
Portland, OR 97204-1134
503.423.3700 Phone 503.423.3737 Fax
Technical Memorandum
To:
Alan Lively, ODOT Local Program Coordinator
From:
Tracy Johnson, Vigil-Agrimis, Inc.
Mark Libby, HDR Project Manager
CC:
Jeff Datwyler, City of Salem Project Manager
Date:
October 25, 2005
Re:
Design Criteria Memorandum - Revised
Project:
Union St. RR Bridge (ATA 23456, WOC1)
Introduction
This technical memorandum describes the minimum standards for the design of pedestrian and
bicycle facilities associated with the first phase of development of Union Street Railroad Bridge
crossing over the Willamette River in Salem, Oregon. The project is intended to meet ADA
standards for accessible design and be suitable for non-motorized mixed uses including:
pedestrians, bicyclists, and in-line skaters.
The City of Salem Comprehensive Park System Master Plan (Salem PMP) and American
Association of State Highway and Transportation Officials (AASHTO) design guidelines (see
References) were used as the primary source for standards. These sources did not provide
direction for several elements of the project including ADA accessibility requirements, lighting, and
interpretive signage. Additional sources were consulted and are listed at the end of this document.
Table 1 provides a summary of the design standards from all reviewed sources.
Mixed (Shared) use compatibility – Multiple User Groups
For a combined user group including cyclists, pedestrians, wheelchair users, in-line skaters and
skateboarders the total paved width of the two-way shared use path should be a minimum of 10feet wide. The Salem PMP notes a preferred minimum width of 12 feet. On new structures, the
minimum clear width should be the same as the approach paved shared use path, plus the
minimum 2-foot wide shoulders.
The designated use of sidewalks as a shared use path is generally unsatisfactory and should be
avoided.
Shoulders and clear zones
AASHTO recommends that a 2-foot wide minimum graded area (shoulder) with a maximum 6:1
slope be maintained adjacent to both sides of the path. In areas where the side slope is greater
than 3:1 or slopes down to a water body, a shoulder width of 5 feet is desirable. The Salem PMP
specifies a 2- to 5-foot shoulder width depending on trail slope. A 3-foot clear zone (clear of
vegetation) is preferred where space permits, and an 8-foot clear zone is desirable for trails
adjacent to paved roads where auto traffic is expected.
Horizontal and vertical clearance
Vertical clearance to obstructions should be a minimum of 8 feet unless maintenance and
emergency vehicle access is anticipated. In such cases, vertical clearance may need to be higher.
General horizontal clearance shall be a minimum of 3 feet.
Horizontal and vertical geometry
HDR Engineering, Inc.
1001 SW 5th Avenue
Suite 1800
Portland, OR 97204-1134
Phone (503) 423-3700
Fax (503) 423-3737
www.hdrinc.com
Page 1 of 7
The minimum radius for a paved shared use path is 30 feet, assuming:
•
•
•
•
a design speed of 12 mph for cyclists
a friction factor of 0.31 for a paved surface
2% superelevation
20% lean angle
The minimum radius for a paved shared use path is 90 feet, assuming:
•
•
•
•
a design speed of 20 mph for cyclists
a friction factor of 0.28 for a paved surface
2% superelevation
20% lean angle
Given the significant difference in curve radii between AASHTO’s 12- and 20-mph design speeds
(30-feet vs. 90-feet), consideration should be given to having a 12 mph bicycle design speed along
the trail, particularly in areas where width is constrained. Widening the paved area at the middle of
a curve can also provide additional space for cyclists and pedestrians to negotiate curves. Signage
that encourages or requires cyclists to slow and/or use caution at a curve and at intersections can
also help to minimize conflicts and accidents.
ADA accessibility
Grades on paved surfaces shall comply with ADA 28 CFR Part 36. Paths graded at less than 5%
slope have no special requirements for landings or handrails, and are preferred where feasible.
Sections that are between 5 and 8.33% slope are considered ramps as specified in the ADA
Guidelines. In such cases, the design shall provide for landings every 30 feet or 30-inch grade
change, with handrails on both sides of the ramp. Where they are required, handrails shall be
affixed to interior of guard rails at a height of 34 to 38 inches. Handrails shall be no more than 1.5
inches in diameter to allow for gripping by people with a range of hand sizes. Cross slope on ramps
shall not exceed 2%.
Structural elements on bridge
Bridge components will be designed in accordance with the AASHTO Guide Specifications for
Design of Pedestrian Bridges, 1997, and the AASHTO Standard Specifications for Highway
Bridges, 17th Edition, 2002, where applicable.
Live Load:
Pedestrian Live Load – 85 psf
Vehicle Load – 10,000 lb. (H-5 Truck) for clear deck width from 6 ft. to 10 ft.
20,000 lb. (H-10 Truck) for clear deck width over 10 ft.
Wind Load:
Trusses and Arches – 75 psf
Girders and Beams – 50 psf
Load Combinations:
In accordance with the AASHTO Standard Specifications for Highway Bridges, except:
Wind on Live Load, WL, shall equal zero.
Longitudinal Force, LF, shall equal zero.
Deflections:
≤ L/500 for members due to service pedestrian live load
≤ L/300 for cantilever arms due to service pedestrian live load
≤ L/500 for horizontal deflection due to lateral wind load
HDR Engineering, Inc.
1001 SW 5th Avenue
Suite 1800
Portland, OR 97204-1134
Phone (503) 423-3700
Fax (503) 423-3737
www.hdrinc.com
Page 2 of 7
Guard Rails
AASHTO recommends a minimum railing height of 42 inches for paths on structures. The Rails-ToTrail Conservancy recommends a 54-inch minimum railing height where bicycle traffic is expected.
Spaces between rails in either horizontal or vertical directions should be less than 4 inches, such
that a 4-inch diameter sphere is unable to pass through any opening.
Lighting
Lighting should be placed outside of the clear zone, except on the bridge. Given the multi-modal
use expected on the Union Street Railroad Bridge crossing, light levels should be in the range of 56 lx (0.5-0.6 foot candles) for the interior sections along the trail. Where the path meets commercial
areas, light levels should be increased to 10 lx (1 foot candle), and at traffic intersections light levels
should be increased to 20 lx (2 foot candles). Stairs shall be illuminated at much higher levels: 200
lx (20 foot candles) for light colored stair surfaces and 500 lx (50 foot candles) for dark colored stair
surfaces.
General Signage
Signage should be clear, legible and well-placed, providing users with information they need in a
timely manner. Signage should have a minimum vertical clearance of 4 feet and a maximum vertical
clearance of 5 feet. Horizontal clearance from the edge of the trail shall be a minimum of 3 feet and
a maximum of 6 feet. Spatial constraints may make it difficult to achieve these minimum standards.
Character height on signage depends on the distance from which the user needs to read the sign,
but ADA specifies that uppercase characters shall be no less than 3 inches tall. If characters
smaller than 3 inches are to be used, height should be based on viewing distance per ADA 28 CFR
Section 36, 4.30.3. Any characters less than 3-inches high shall also meet the tactile requirement
(raised a minimum of 1/32"). A preferred maximum character height of 3 inches is recommended,
for this project, in order to maintain reasonable sign sizes.
Interpretive Signage
Interpretive signage should be setback a minimum of 18 inches from the edge of the trail, with 24
inches being the preferred distance. The height of the sign should be no less that 36 inches and no
more than 42 inches. A Braille strip should be located on the outer edge of any interpretive sign.
Streetcar Design Criteria
Streetcar design criteria is included in this document for discussion purposes, as it may pertain to a
potential future streetcar system. The existing railroad rails would be removed during initial trail
construction phases.
Given the nature of the streetcar being a multi-modal application and being a relatively new
application; the streetcar does not have documented design criteria that is sited by an organization
such as AASHTO. The criteria sited is the technical specification of the vehicle manufacturer (The
Inekon Group).
It is worth noting that ODOT Rail Safety Division may take an active role developing the criteria as
the project approaches final design stages. They did not play a significant role in the Portland
Streetcar design criteria, but reserve the right to be involved in the process. They do not have
defined criteria concerning streetcars, but want to make sure it will be safe for the public.
Vehicle Specifications:
The streetcar vehicle is 66 feet long, 8'-10" wide, by a height of 12'-9" and has an average vehicular
weight (empty) of 63,500 lbs. Due to the relatively short wheel base of the vehicle, the minimum
horizontal curve radius is 60 feet. The maximum grade the streetcar can operate over is 9 percent,
and the minimum length of vertical curve is 62 feet to provide a smooth transition and ride for
HDR Engineering, Inc.
1001 SW 5th Avenue
Suite 1800
Portland, OR 97204-1134
Phone (503) 423-3700
Fax (503) 423-3737
www.hdrinc.com
Page 3 of 7
passengers between differing grades. A 25-foot minimum spiral will be incorporated between
tangents and curves to transition the superelevation needed for the vehicle.
Horizontal and Vertical Clearances:
Horizontal clearance to any obstruction should be 8'-11", increased by 1½" per degree of curvature
throughout the curved areas. Due to the low speeds of the vehicle and the nature of application, it is
meant to intermingle with the pedestrian traffic; therefore, there will not be an additional allowance
between the vehicle and bicyclist or pedestrian.
Vertical clearances shall be a minimum 14'-0" and a maximum of 20'-6", which includes the
Overhead Catenary System (OCS) contact wire. The typical OCS pole spacing is 65-80 feet on
tangents, but curves will require reduced pole spacing depending on the radius.
Track Section:
The streetcar rail should be imbedded into the trail, e.g. a concrete slab or asphalt pavement. Other
surfaces could be used, but will have to provide a tight fit against the outside edge (field side) of rail.
On the inside edge (gauge side) of the rail, the surface will have to be notched out to provide room
for the flange of the vehicle wheel. This notch in the surface shall be a minimum of 2 ¼", and a
maximum of 2 ¾" wide at a depth of 1 ½". This notch may be a concern to bicyclists, but does not
seem to be an issue with the Portland Streetcar as it functions in many multi-use areas without
warning devices.
Table 1: Summary of Design Standards
Category
Element
Criteria
MIN.
Trail Width
Note: Shoulder and clear area
dimensions are below
Shoulders and Clear Zones
(measured from edge of trail)
Horizontal and Vertical
Clearance
Horizontal and Vertical
Geometry
(assumes 2% superelevation)
ADA Accessibility
Structural Bridge Elements
mixed use pathway
mixed use pathway (primary)
trail shoulder
trail shoulder
clear zone (dist. to vegetation)
buffer (dist. to road edge)
10'
10' (12'
preferred)
2'
2'
3'
8'
vertical clearance (general)
horizontal clearance (general)
8'
3'
curve radii (12 mph design speed)
30'
curve radii (20 mph design speed)
trail cross-slope
trail slope w/o handrails
trail slope with handrails
handrail height
grab bars (w/ 1.5” clear behind)
90'
pedestrian live load
vehicle load
wind load – trusses and arches
wind load – girders and beams
HDR Engineering, Inc.
5%
34"
1.25" dia.
85 psf
10,000 lb.
75 psf
50 psf
1001 SW 5th Avenue
Suite 1800
Portland, OR 97204-1134
MAX.
as space
allows
5'
as required
Reference
(See sources list)
AASHTO(1)
Salem PMP
AASHTO(1)
Salem PMP
Salem PMP
Salem PMP
AASHTO(1)
AASHTO(1)
AASHTO(1)
2%
<5%
8.33%
38"
1.5" dia.
20,000 lb.
AASHTO(1)
ADA
ADA
ADA
ADA
ADA
AASHTO(3)
AASHTO(3)
AASHTO(3)
AASHTO(3)
Phone (503) 423-3700
Fax (503) 423-3737
www.hdrinc.com
Page 4 of 7
Guard Rails
Note: In at least one direction
the maximum spacing must
be no more than 4"
member deflections
cantilever deflections
horizontal deflections
top railing height
top railing height (w / bikes)
vertical and horizontal space
between rails
L/500
L/300
L/500
42"
vertical and horizontal space
between rails
bikeway light levels (parks)
bikeway light levels (commercial
areas)
bikeway light levels (traffic
intersections)
Lighting
General Signage
Interpretive Signage
HDR Engineering, Inc.
pedestrian light level (park)
pedestrian light level (stairs, light
colored surface)
pedestrian light level (stairs, dark
colored surface)
pedestrian light level (commercial
areas)
vertical sign clearance
horizontal sign clearance
character height
braille strip
setback from pathway
height
54"
AASHTO(3)
AASHTO(3)
AASHTO(3)
AASHTO(1)
RTTC Trail book
6"
AASHTO(3)
4"
UBC
6 lx (.6 fc)
IESNA
10 lx (1.0 fc)
IESNA
20 lx (2.0 fc)
22 lx (2.2 fc)
LATSS, AASHTO(2)
5 lx (0.5 fc)
IESNA
200 lx (20 fc)
IESNA
500 lx (50fc)
IESNA
10 lx (1.0 fc)
4'
5'
3'
6'
3"
3" preferred
outside edge of sign
18"
24" preferred
36"
42"
IESNA
AASHTO(1)
AASHTO(1)
ADA (for minimum)
LATSS
LATSS
LATSS
1001 SW 5th Avenue
Suite 1800
Portland, OR 97204-1134
Phone (503) 423-3700
Fax (503) 423-3737
www.hdrinc.com
Page 5 of 7
HDR Engineering, Inc.
1001 SW 5th Avenue
Suite 1800
Portland, OR 97204-1134
Phone (503) 423-3700
Fax (503) 423-3737
www.hdrinc.com
Page 6 of 7
References
AASHTO (1)
AASHTO (2)
AASHTO (3)
AASHTO (4)
RTTC
LATSS
Salem PMP
ADA
IESNA
ODOTBPP
UBC
HDR Engineering, Inc.
AASHTO. 1999. Guide for the Development of Bicycle Facilities. American
Association of State Highway and Transportation Officials. Washington, D.C.
AASHTO. 2004. Guide for the Planning, Design, and Operation of Pedestrian
Facilities. American Association of State Highway and Transportation
Officials. Washington, D.C.
AASHTO. 2002. Standard Specifications for Highway Bridges, 17th Edition.
American Association of State and Highway Transportation Officials
Washington, D.C.
AASHTO. 2002. Standard Specifications for Highway Bridges, 17th Edition.
American Association of State Highway and Transportation Officials.
Washington, D.C.
Flink, Charles A., Kristine Olka, and Robert M. Searns. 2001. Trails for the
21st Century: Planning, Design and Management Manual for Multi-Use
Trails. Washington, D.C.: Island Press.
Harris, Charles W. and Nicholas T. Dines. 1998. Time-Saver Standards for
Landscape Architects, Second Edition. Washington, D.C.: McGraw Hill
Publishing Co.
Salem Comprehensive Park System Master Plan. 1999. McKeever/Morris,
Inc.
Code of Federal Regulations, 28 CFR Part 36. ADA Standards of
Accessibility Design. Washington, D.C., September 2002 or most current
edition
Illuminating Engineering Society of North America, Mark Rea, (ed.) IES
Lighting Handbook, Reference Volume and Application Volume, IES, New
York, 1993.
Oregon Department of Transportation. 1995. Oregon Bicycle and Pedestrian
Plan, An Element of the Oregon Transportation Plan, Adopted by the Oregon
Transportation Commission June 14, 1995.
The International Conference of Building Officials. 1997. Uniform Building
Code, Volume I, Administrative, Fire- and Life-Safety, and Field Inspection
Provisions. Section 509.
1001 SW 5th Avenue
Suite 1800
Portland, OR 97204-1134
Phone (503) 423-3700
Fax (503) 423-3737
www.hdrinc.com
Page 7 of 7