Please Save Frith

1
Please Save Frith
2
Main Menu
3
Introduction What is Frith?
Frith Road Bridge?
The Frith Road Bridge, crossing the Pine River in
St. Clair County, is a historic metal truss
bridge that does not meet the county's
requirements for weight and traffic capacity. The
St. Clair County Road Commission wants to build a
replacement bridge. They are willing to give the
historic bridge to Pine River Nature Center.
4
Introduction
Where is the Bridge?
Pine River Nature Center
Pine River
Current Bridge Location
5
About Truss Bridges Truss Intro
What Truss Bridges Are
Truss bridges are bridges whose main structure is
a triagular framework.
The Original Blue Water Bridge is a special type
of truss bridge and is known as a cantilever
bridge.
6
About Truss Bridges Pony vs Through
Truss Bridge Types
If the trusses run beside the deck, with no cross
bracing above the deck, it is called a pony truss
bridge.
If cross-bracing is present above the deck of the
bridge, then the bridge is referred to as a
through truss.
7
About Truss Bridges - Deck and Arch
Truss Bridge Types
If trusses run under the deck, then the bridge is
a deck truss bridge.
This bridge is not a truss bridge, although it is
referred to as a trussed arch, since the arch is
built of a triangle framework.
8
About Truss Bridges Truss Parts
Parts of a Truss Bridge
The different parts of a truss bridge are all
named. Some of the parts
Top / Upper Chord
Vertical Member
Diagonal Member
Bottom / Lower Chord
Portal Bracing
Sway Bracing
V-lacing on vertical member
9
About Truss Bridges - Connections
Connections Riveted / Pinned
The pieces of the framework of a truss bridge are
held together by connections. Connections can be
either riveted or pinned.
Riveted
Riveted
Riveted
Pinned
Pinned
Pinned
Pinned connections can be identified by the bolt
going through the loops of the members.
10
About Truss Bridges - Pratt
Configuration of Trusses
There are several ways of configuring the
diagonal members of truss bridges. The most two
common configurations are Pratt and Warren.
In a Pratt configuration, diagonal members angle
towards the center and bottom of the bridge.
Sometimes extra and often smaller diagonal
members may be present that do not follow this
rule.
11
About Truss Bridges Warren
Configuration of Trusses
In a Warren configuration, diagonal members angle
in alternating directions, forming a v shape.
Vertical members may separate some of these v
shapes.
Although not always, Pratt configurations tend to
be on older turn of the century truss bridges,
and Warren configurations tend to be on the newer
1920s-30s truss bridges.
12
About Truss Bridges Complexity
Complexity and Beauty
Truss bridges are a very complex type of bridge.
Intricate geometry and engineering works together
to hold these structures up. There are many more
configurations, shapes of truss bridges, and
there can be combinations of those. Truss bridges
are a work of intricate art as well. Whether it
is a huge landmark bridge, or a small bridge
tucked away in the country, each one is unique in
its own way. These bridges were built in a time
when a lot more attention was paid to detail and
aesthetic appearance.
13
About Truss Bridges Reality
Truss Bridge Reality
Despite their complexity, truss bridges are a
thing of the past. The truss bridge era began
roughly in the 1880s and ended roughly in the
1930s. Modern bridge building has reached an
unprecedented simplicity. Truss bridges are
usually replaced with what amounts to a simple
slab of concrete held together by reinforcing
rods. These modern bridges are built to a
standard plan and they all look the same. Some
modern bridges are so plain that you might not
even notice if you are crossing one. Bridges
built today are no longer eye-catching landmarks.
14
About Truss Bridges Reality
Truss Bridge Reality
The Church Road Bridge located south of M-46 near
Carsonville in Sanilac County was replaced in the
Summer of 2004. The pictures below contrast the
through truss bridge to the replacement concrete
span.
15
About Truss Bridges Reality
Truss Bridge Reality
Although a few have been preserved, the majority
of truss bridges have been demolished, are going
to be demolished, or are simply abandoned to rot
away. This is why we need to save the Frith Road
Bridge!
16
Technical Information Frith Road
The Frith Road Bridge
The Frith Road Bridge is a Pratt through truss.
Its connections are pinned .
17
Technical Information Spans and Size
Spans and Size
The Frith Road Bridge includes wooden approach
spans at each end and the main steel truss
span. The deck of the bridge is 16 feet
wide. From the bottom of the deck to the top of
the sway bracing, the bridge is 20 feet.
Including the approaches, the bridge is 180 feet
long. Excluding the approaches, the bridge is
about 113 feet long.
18
Technical Information Approaches
Approaches
Simple beam spans provide an approach to the
bridge. There are two approach spans at the west
end, and one approach span at the east end. They
are constructed of wood stringers and supported
by concrete. Each span is 22 feet long.
West Approach (2 Spans)
East Approach (1 Span)
19
Technical Information Approach Supports and
Abutments
Approach Supports and Abutments
The approach spans are held up by the abutments,
and the main span supports. The west approach
also has a concrete pier. The west approach
concrete support appears to have been repaired at
some time
The abutments for the bridge are of concrete, and
are similar in appearance to the approach
supports. Compared to other historic truss
bridges, these abutments are simple in design and
very small.
20
Technical Information Main Span Supports
Main Span Supports
The main truss span is supported by steel
caissons, which are filled with concrete on the
inside. Some of these caissons have slowly been
beginning to tip over, which will begin to put
the bridge at risk if not dealt with.
21
Technical Information Deck
Deck Structure
The deck is wooden with an asphalt layer on top.
This is not the original deck. Support under the
bridge comes from both steel i-beams as well as
wooden beams. The only place where paint appears
to be is on the steel i-beams. This paint is a
rusty red in color.
22
Technical Information V-Lacing
V-Lacing
V-lacing is present on the sway bracing and
vertical members.
23
Technical Information Portal Bracing
Portal Bracing
The portal bracing on the Frith Road Bridge is
referred to as an A-Frame design.
Portals and guardrails (if original) are widely
varied, and were a portion of the bridge where
the builders could use their imagination.
The Frith Road Bridges portal bracing would have
been considered plain and simple when it was
built. Nevertheless, it is still a very
attractive part of the bridge.
24
Technical Information Turnbuckles
Turnbuckles
Turnbuckles are present on the diagonal members
which were designed to adjust tension. One set of
the turnbuckles appears to have been replaced
long ago.
Newer turnbuckles welded on.
25
Technical Information Diagonal Bracing Rods
Diagonal Bracing Rods
The diagonal bracing between the top chords
appears to have been rebuilt or repaired.
Part of the original connection.
Redone connection.
26
Technical Information Guardrails
Guardrails
The original guardrails have been replaced with
modern guardrails. This was supposedly done in
the 1970s. A historical photograph of the bridge
indicates that the bridge originally had simple
metal pipes for guardrails.
These guardrails are mounted directly to the
v-laced vertical members of the bridge, rather
than to the deck or i-beams below. The weight of
the guardrails, which essentially are hanging on
the bridge, are slowly enlarging the holes where
the bolts go through the vertical member.
27
Technical Information Crash Damage
Crash Damage
Frith Road Bridge was closed January 9, 2004
after a car hit the guardrails and damaged one of
the vertical members.
Because the guardrails are attached directly to
the vertical members, the guardrail transferred
the impact pressure directly to the bridge.
28
History The Beginning
The Beginning
Construction of the Frith Road Bridge was
undertaken in 1914 supposedly by the township,
and remained under township jurisdiction until
1934. Historic maps indicate that the current
truss bridge was not the first crossing at the
location. A school was located in the area near
the bridge. On March 13, 1934, Frith Road,
including the bridge, was transferred to the St.
Clair County Road Commission.
29
History - Significance
Statewide Significance
The Frith Road Bridge was one of the last pin
connected Pratt through truss bridges built in
Michigan.
Its length is considered long due to the approach
spans. It is 180 feet in all.
It is a good example of the traditional Pratt
through truss bridge design.
30
History Local Importance
Local Importance
Frith Road Bridge has a large amount of local
significance and rarity.
Frith Road Bridge is the last through truss
bridge on St. Clair County Roads.
The demolition of the Church Road Bridge near
Carsonville in the summer of 2004 made this
bridge the last through truss bridge in the
eastern part of the thumb.
If current plans to relocate or demolish the
Indian Trail and Speaker Road pony truss bridges
succeed, Frith Road Bridge will be the last
highway truss bridge of any kind in St. Clair
County.
31
History A Rough Survey
A Rough Survey
In my efforts to locate and photograph area truss
bridges, I learned how scarce truss bridges are
by writing the road commissions and requesting
locations of any truss bridges
Sanilac County is left with one pony truss
bridge, scheduled for demolition.
!
Macomb County has three pony truss bridges, all
abandoned and in very poor condition.
!
Tuscola County has one pony truss, scheduled for
demolition in 2005.
!
Oakland county has no truss bridges!
X
32
History A Rough Survey
A Rough Survey
Saginaw County is the closest happy story, with
two restored through truss bridges, and several
other abandoned truss bridges. The closest
restored bridge is 70 miles away from the Pine
River Nature Center and is just outside
Frankenmuth.
33
Bridge Condition - Paint
Paint
The Frith Road Bridge Needs Help!
The Frith Road Bridge is a steel bridge, and
should have a layer of paint to protect it. The
Frith Road Bridge has rusted so much that there
is no paint visible on any part of the bridge,
with the exception of possible paint on the
i-beams below the deck.
34
Bridge Condition Rust Damage
Rust Damage
Rust A Truss Bridge Killer
The severe rust which has developed has caused
considerable damage to many areas of the bridge
under or beside the deck.
35
Bridge Condition Connections
Connections
Connections along the deck have taken a lot of
damage from the rust.
36
Bridge Condition Broken Rods
Broken Rods
Some bracing rods under the deck have rusted so
bad that they have broken off and bent.
37
Bridge Condition Rivet Rust
Rivet Rust
Some of the rivets inside the top chord near the
deck have rusted so bad, that they look like some
sort of strange fungal growth on the bridge!
38
Bridge Condition Looking at the Bright Side
Looking at the Bright Side
At the opposite end, the situation is much
brighter, and not just because of the sunlight
there is much less rust damage up here.
39
Bridge Condition Looking at the Bright Side
Looking at the Bright Side
The Frith Road Bridge is in bad condition, but it
is still definitely restorable. The bridge has
sat un-cared for long enough it is time to start
working to save it!
40
Restoration - Beyer Road
Example Restoration
Example Restoration Beyer Road Bridge
This bridge is located just west of Frankenmuth
and was restored at its original location.
41
Restoration - Repairing Joints
Example Restoration
Example Restoration Beyer Road Bridge
Repairs made to the approach span (left) show how
a rusted joint, as seen on the main span (right)
can be repaired.
42
Restoration - Before and After
Example Restoration
Example Restoration Beyer Road Bridge
Before
and
After
43
Restoration - A New Life
Example Restoration
Restoring a historic truss bridge really does
give the bridge a new life Hopefully, this new
life can be given to the Frith Road Bridge!
44
Restoration - Grand Finale
A New Life
Restoring a historic truss bridge really does
give the bridge a new life Hopefully, this new
life can be given to the Frith Road Bridge!
45
Restoration - Please Save Frith