Muddy Consultants Presents: Big Muddy Trail Area Restoration

TL- Alex Watson Graham Burkholder Danny Shannon

Clark Hartmann Jeremy Metz Mike Grassi

University of Missouri - College of Engineering

E3508 Lafferre Hall

Columbia, MO, 65203

Cell: 816-805-6251 Email: alexywatson@gmail.com

Executive Summary

Arrow Rock is a small town about 40 minutes West of Columbia. The Big Muddy Fish and

Wildlife Refuge is just East of the town and is in need of restoration. The main problems are as

follows: flooding makes the trail inaccessible several times a year, the decaying bridge, the

erosion of the old levee, erosion of the trail, and limited parking space for visitors.

After an initial site investigation Muddy Consultants were able to discover more about the trail

area. The existing wooden pedestrian bridge is decaying as a result of high humidity and frequent

flooding. During the site visit Muddy Consultants found that a spring water stream feeds into the

stream and directly into the side of the levee. The spring enters just downstream of the bridge.

This causes turbulence which has eroded much of the old levee. In order to proceed, the stream

needs to be redirected and/or the levee needs to be armored with riprap. The trail that leads up to

the bridge is also in danger of erosion as a smaller stream runs along side. Lastly, Muddy

Consultants found that the site sub surface is almost entirely made up of soft clays and silts. This

soil has a strength of between 250 and 300 psf.

Muddy Consultants was tasked with addressing the issues stated above and doing so under

certain requirements. The trail needs to be accessible during flood events so that visitors can

enjoy the trail at all times. The existing bridge is decaying and is overtopped frequently. It needs

to be replaced with a bridge that will span from the height of the top of the levee. Any

construction must be done with little to no use of large vehicles since the trail is not very heavy

vehicle accessible. New construction needs to have minimal impact on the environment. Future

maintenance needs to be minimal. Finally, Muddy Consultants was given a tentative budget of

$250,000.

Initially, Muddy Consultants believed a truss bridge made of weathering steel, with connecting

catwalk would be the best solution to the main issue. While it would keep the path above flood

waters, this solution is most likely not an option. This is because the bridge will weigh too much

to lift by helicopter. Due to that major issue Muddy Consultants now suggests a bridge made of

two weathering steel I-beams. This type of bridge will cost much less and will be much easier to

construct. Muddy Consultants also suggest armoring the bank opposite the spring water stream

to prevent further erosion of the levee. Step pools are suggested to slow down the flow under the

bridge to further prevent erosion. Muddy Consultants has completed drawings and cost analysis

for the suggested items.

Introduction and Current Situation

Muddy Consultants intends to replace a bridge and improve trail accessibility for the Big Muddy

Fish and Wildlife Refuge. The current bridge cannot always serve its purpose as it is often

underwater during flood events. This bridge deck is made of wood, which is currently rotting.

Tim Haller, the Visitor Services Manager for Big Muddy, has proposed that Muddy Consultants

should come up with a plan to replace this bridge as well as fix some other issues in the area

(Figure 1). As a team, we have decided what we are going to recommend and how to improve

the area.

Figure 1: Bridge and Stream Erosion Looking Upstream

The first key issues are deciding the location for the new bridge as well as what type of bridge to

use. The old wooden bridge is in poor condition as a result of flooding in the area. High

humidity and low sunlight has caused the current bridge to rot (Figure 2). The new bridge will

need to be placed higher up on the levee so it is above flood waters. This is the main issue, but

there are several others that need to be dealt with. The next issue is a spring water stream that

intersects with the bridge stream just downstream of the bridge.

Figure 2: Underside of Bridge; The Rotting Bridge Deck

The spring connects to the bridge stream at about a 90 degree angle. When water flows in from

the spring it creates turbulence that has eroded part of the levee. Muddy Consultants

recommends to redirect this spring water stream for the new bridge to be successful. Our third

issue concerns the rip-rap protecting the current bridge. It is in bad condition and might need to

be replaced. Another issue is a much smaller stream that flows under the trail by the parking lot.

Lastly, Tim Haller would like Muddy Consultants to look at redoing the parking lot nearest to

the bridge. Altogether, Tim Haller would like the new trail and bridge to keep trail-goers above

the flood water. This will allow people to enjoy the wildlife refuge, even during floods.

Figure 3: Spring entering the stream perpendicular to levee causing erosion

to

Objectives and Requirements

Muddy Consultants plans to address several issues in the Big Muddy Fish and Wildlife Refuge

including existing bridge replacement, trail accessibility, flooding control measures, and some

other issues brought up by Tim Haller or noticed by our firm. Our firm recommends replacing

the current bridge with a steel alternative or suspension alternative. Either way, the current

bridge is becoming unstable and rotted, leading to a possibility of danger for future bridge users.

The current trail floods several times a year and our solution is a possible elevated walkway over

the existing trail. This will allow visitors to visit the wildlife refuge while flooding is occurring.

Our new bridge will be at the height of the levee allowing the bridge greater longevity by

reducing exposure to water. Levee cutting is a current issue that needs to be immediately

addressed. We propose a large amount of rip rap in the levee cutting area to reduce erosion and

stabilize the stream bank. The small stream area near the trailhead was looked at and flooding

mitigation will be considered although this area is not going to be our main focus. The current

streambank stabilization methods have almost completely washed away (Figure 4) and are in

need of repair and replacement. Lastly, Muddy Consultants will come up with new strategic

locations to place riprap and geotextile in order to limit erosion in the bridge area. Lastly, our

firm suggests an updated parking options so that visitors may have easier access to the trail and

to promote the trail itself.

Figure 4: Rip rap removed due to high water velocities

Environmental Impact

Muddy Consultants plan to implement a responsible and sustainable environmental strategy to be

used in order to ensure minimal disturbances during the construction of the bridge and trail. Our

design team made an emphasis to lie lightly on the land when considering bridge options and

walkway alternatives. Our firm will also recommend a tree replacement or native vegetated areas

program to improve the trees which may be removed during the construction phase. During the

construction phase Muddy Consultants recommends that proper environmental protections

practices are used such as silt fences and swales where necessary. Overall, we do not see any

major environmental impacts for this project but will continue accessing any risks throughout the

entire design process.

Hydrology

Muddy consultants have computed hydrology information regarding the bridge site in order to

get a gauge of necessary flooding and erosion protections. Using data from NOAA and the

NRCS manual, our team has computed peak flows and velocity for the roughly 1.67mi2

watershed designated by our team below.

Figure 5: Watershed for Flows Passing Through Bridge Site

Using Manning's Equation for flow velocity as well as 7.61in of expected rainfall in this area,

our team has calculated that in a 100-year storm event, flows from the creek and peak at up to 11

ft/s. This seems like an extremely high flow but it is important to keep in mind this number is

only for a worst case scenario expected about every 100 years. Any bridge abutments or columns

will be designed to withstand flows at this magnitude. Next, we computed the flows that could

possibly be passing through the site during a 100-year storm event, another worst case scenario.

Flows have been calculated to be up to 767 cfs in a storm event specifically from the watershed

shown. Additional flows from the Missouri River and further upstream can contribute during

these storm events. Our recommendations are to install hydraulic structures upstream from the

bridge to slow high velocity flows in order to reduce cutting and erosion. An example of a

possible hydraulic structure could be rip-rap step pools. Rip Rap is also recommended to be used

along the levee downstream from the bridge in order to reduce cutting which has become a

serious problem recently. Cost analysis for rip-rap can be found in the cost analysis section of

this report. Additional hydraulic information can be found at the appendix of this report.

Truss Bridge Options

The replacement bridge would be a steel truss bridge made of prefabricated 100 ft spans. The

cost of each of these spans is approximately $118,900 per span before construction. This range is

so large because there is so much variability in the bridge properties such as material, shape, and

other factors specific to the project. This bridge will be designed economically, so a cost closer

to the low end of that range can be expected.

Since this is a pedestrian bridge, the only loads being designed for are pedestrian loads, which,

according to AASHTO, means accommodating a 10,000 lb H5 truck, as well as a uniform

pedestrian load of 90 psf (AASHTO 2009). The spans would be 8 ft wide to allow for

comfortable use. The deck on this bridge would be made of wood or recycled plastic planks. The

truss itself would be a Pratt truss, shown in Figure 7, as this type of truss is the cheapest and most

common for pedestrian bridges (Excel Bridge 2018).

Figure 6: Example of a Pratt truss shape

The bridge can be constructed in one of two ways. Figure 8 shows the differences. In the first

approach, the bridge would be a straight 300 ft shot from the top of the levee to the trail made of

three 100 ft spans. This method would create the most direct path for visitors, and would require

the least maintenance, as it will be entirely made of steel. It would, however, also require several

trees to be cut down or otherwise relocated, and the cost of fabricating and placing these spans

would take up most of or exceed the budget. The second method is a single 100 ft span of the

truss bridge from the top of the levee, and a meandering wooden catwalk the rest of the distance,

adjacent to the current trail. This reduces the number of trees that would need to be relocated,

and greatly lowers the cost. The only downside is the somewhat increased need for maintenance

on the catwalk, although there are strategies for mitigating that need, which will be covered later

in this report.

Figure 7: Example of the paths of the three 100’ spans vs one 100' span with catwalk

I-Beam Bridge Option

After receiving a quote from a bridge manufacturer for a 120ft span across the creek, Muddy

Consultants decided to come up with another solution to help minimize costs for the Fish and

Wildlife Service. Another option besides a prefabricated bridge can be a custom bridge of I-

beam girders holding up the decking and railing that is chosen. A single span option will be free

of the problems the Fish and Wildlife Service are facing with the current bridge such as piers

being undercut. This option would only require two I-beam girders attached at both ends with

Three Spans

N Single span and catwalk

concrete piling. However, Muddy Consultants also recommends constructing a MSE wall at the

levee side to reduce girder span lengths. This MSE wall will need to be protected by rip-rap for

high velocity flow scenarios. It may be possible to connect the I-beam girders directly to the

MSE wall eliminating the need for a concrete pile on the levee side. In all, the I-beam bridge

will save Big Muddy more than $50,000 compared to the steel truss bridge.

Figure 8: Proposed I-Beam Bridge Crossover with Abutments

Spanning the entire creek, the I-beams could start to get costly after 25ft as this is the maximum

length most manufactures will carry without a custom order being made. As far as

constructability goes, typical weights for these types of I-beams are 31.8lb/ft.

Steel Options

If a steel truss bridge is used to replace the current wooden bridge, the type of steel will be an

important aspect. There are three options for this project: painted steel, galvanized steel, and

weathering steel. Each type of steel has its own benefits and drawbacks.

Painted steel can be very aesthetically pleasing, but it has a few drawbacks. The biggest issue is

that it requires occasional touchups and may need to be completely repainted every 15 years.

This of course depends on the quality of paint used. One of the most important criteria for the

client is to decrease maintenance. If these touchups are not performed, the steel will oxidize

more rapidly and thus decrease the service life of the bridge. This makes painted steel less

desirable. On top of that painted steel is actually more expensive than weathering steel.

However, it is still far less expensive than galvanized steel.

Weathering steel is the second option for the proposed bridge. This type of steel is also

aesthetically pleasing considering the proposed location. The outer layer of the weathering steel

oxidizes over 3 – 12 months. This outer layer slows oxidation for the rest of the steel and can

allow the bridge to last up to 120 years (Corus Construction and Industrial 2005). Since the steel

naturally forms a protective layer it requires very little maintenance. Weathering steel is also the

cheapest option between the three types of steel. It is 5% cheaper than painted steel (Corus

Construction and Industrial 2005). The biggest issue with weathering steel is that it does not do

well in excessively humid environments; however, excessively humid refers to climates of

continuous humidity. A cycle of wet and dry is beneficial to weathering steel’s controlled

corrosion process. The trees drop their leaves in the fall which greatly reduces the humidity in

the area during the colder months. Therefore, this site will not have any problems with excessive

corrosion.

Galvanized steel is the third and final option for the bridge spans. The biggest hit against

galvanized steel is its cost. It is far more expensive than the other two types because the steel is

dipped in molten zinc. The zinc coating protects the steel from oxidizing. As far as oxidation

mitigation goes, galvanized steel is better than the other two. Another issue with galvanized

steel is the aesthetics. A large, shiny, silver bridge may look out of place in the middle of a

wildlife refuge.

Muddy Consultants suggest using weathering steel for the proposed bridge. It is the most

economic option, and perhaps the most aesthetically pleasing for the given environment. The

fact that weathering steel requires little maintenance over its design life is also an important

factor in this choice. Weathering steel does not perform well in “excessive humidity.” However,

Big Muddy does not fit this description since it is not continuously humid through the seasons.

This means weathering steel will not oxidize too quickly and is therefore the best candidate for

the proposed bridge.

Type of Steel

Criteria Weathering Painted Galvanized

Initial Cost

Maintenance

Corrosion

Resistance

Aesthetics

Table 1: Benefits and Drawbacks for Each Type of Steel

Bridge Placement Options

Originally, Muddy Consultants planned to have the prefabricated bridge delivered to the site and

then use a helicopter to get it in place. This seemed the best option because it is close to, if not,

impossible for large machinery to access the site. Unfortunately, the bridge will be too heavy for

a helicopter to lift. CONTECH estimated that the heaviest crane pick for the proposed 120ft

bridge would weigh 45,400lbs. The United States Military’s largest helicopter is the Sikorsky

CH-53E Super Stallion. It can only carry 14.5 tons externally (Helipress 2017) which means the

helicopter could not lift the bridge. The only other option is using cranes to lift the bridge into

place. Big Muddy is not the ideal place for cranes since there are many trees and the soil is very

soft. There are cranes that can lift the proposed bridge, but they are too big to access the bridge

site. That is true unless a lot of trees are cut down. For these reasons Muddy Consultants now

recommends the I-beam system discussed earlier, instead of a steel truss bridge.

Proposed Bridge Abutment

Muddy Consultants proposes that Mechanically Stabilized Earth (MSE) Walls be constructed at

each end of the bridge to serve as abutments. MSE walls were selected due to their relatively low

cost, ease of construction, and lack of maintenance required throughout the design life. MSE

walls are common for single span bridges (Bourdeau & Zevgolis 2007), and their reduced

“bump” at the ends of the bridges is ideal for bike and ATV traffic. Additionally, MSE Walls are

less susceptible to differential settlement compared to other abutment options (Bourdeau &

Zevgolis 2007). Muddy Consultants recommends that new fill is brought to the site and is used

as the backfill for the MSE walls due to the low strength of the clay currently at the site.

Proposed Catwalk

Muddy Consultants proposes that an elevated catwalk be built next to the existing trail to allow

access to the area during flooding (Figure 9). The catwalk is to be built next to the existing trail

to allow for use of the trail during construction of the catwalk. The catwalk should comply with

current ADA standards upon completion of construction to allow everyone to enjoy the trail.

Muddy Consultants proposes that the catwalk deck is to be made from either pressure treated

plywood or HDPE (High Density Polyethylene) plastic lumber. The main advantage of plywood

over plastic is that its initial cost is two to three times less than that of recycled plastic.

Additionally, it is more commonplace, therefore making it easier to acquire the materials with

the desired strength and appearance. Even though recycled plastic is more expensive up front, the

client is likely to save more money later on because recycled plastic does not deteriorate like the

wood and requires less maintenance. Most wood decks have a 15 year life span (123 Remodeling

2015), but when exposed to excessive moisture without proper maintenance, the lifespan can be

even less. HDPE plastic lumber has a 50 year lifespan, and most manufacturers even provide a

50 year warranty on their product (123 Remodeling 2015). Additionally, by selecting recycled

plastic as a building material, the client is re-using a product that would otherwise end up in a

landfill.

Figure 9: Plan View of Proposed Catwalk

Geotechnical Investigation

Since no existing soil information was provided for the site, Muddy Consultants performed field

tests on the soil. A split spoon sampler was driven into the ground (Figure 10) and pocket

penetrometer tests were performed on the soil sample at two different depths. The pocket

penetrometer gave unconfined compressive strength readings of 0.9 tsf at the surface and 1.5 tsf

6ft below the ground surface. These readings correlate to undrained shear strength (Su) values of

450 psf and 750 psf respectively. Based on these readings, the soils were defined as soft clay and

medium clay respectively (Coduto 1999). Our team does not anticipate that rock will be

encountered within the top 20 ft of soil being considered in our design. The groundwater table

depth was assumed to be at the surface due to flooding at the site. Based on these assumptions

and the soil sample obtained from the field, a preliminary soil profile was created (Figure 11).

Figure 10: Soil sample from Big Muddy Trail site

Figure 11: Preliminary soil profile for the Big Muddy Trail site

Pocket

Penetrometer

Split Spoon

Sampler

Proposed Catwalk Foundation

For the catwalk foundation, our team proposed that drilled piles be used due to the softness of the

clay on site and the lack of heavy machinery required. Our team suggests that the piles be either

timber or concrete. Timber piles have the lower cost and are easier to construct than concrete

piles, however, they are not as durable as concrete piles when subjected to cycles of wetting and

drying. Therefore, Muddy Consultants recommends using concrete piles if the extra money is

available. Pile lengths, diameters, and spacing were designed to hold an H5 truck and 90 psf

pedestrian live load according to AASHTO’s Pedestrian Bridge Standards. Muddy Consultants

recommends placing pair of 1.5 ft diameter piles spaced 25 feet apart and drilled 19 ft below the

ground surface. This design was based on the ultimate capacity of the piles with a factor of safety

of 3.0. Figure 12 shows a graph of skin friction, base resistance, and ultimate load capacity of the

piles vs depth. Skin friction and base resistance values were found based on the pocket

penetrometer readings from the site investigation. The ultimate load capacity of the piles is the

sum of the skin friction and base resistance. Additionally, this design was chosen because it will

require the least volume of materials compared to other spacing, length and diameter options

(Figure 13), and it will have sufficient uplift capacity (Figure 14). Figure 15 shows a sketch-up

for the timber supports and the concrete supports.

Figure 12: Skin friction, base resistance, and ultimate load vs depth for a 1.5’ diameter pile

0.0

2.0

4.0

6.0

8.0

10.0

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14.0

16.0

18.0

20.0

0 10 20 30 40 50 60

Dep

th (

ft)

Load (k)

Skin Friction (Fs)

Base Resistance (Qb)

Ultimate Load (qult)

Figure 13: Material volume for various pile spacing and depth options

Figure 14: Uplift capacity for various pile spacing and depth options

0.00

10.00

20.00

30.00

40.00

50.00

60.00

70.00

5' Spacing7' Depth

10' Spacing10' Depth

15' Spacing13' Depth

20' Spacing16' Depth

25' Spacing19' Depth

Mat

eria

l Vo

lum

e (y

d^3

)

Pile Spacing and Depth Options

Material Volume

0

5

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5' Spacing7' Depth

10' Spacing10' Depth

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Up

lift

Cap

acit

y (k

)

Pile Spacing and Depth Options

Uplift Capacity (k)

Figure 15: Supports for Catwalk

Connections

To ensure safety of pedestrians and wildlife, as well as for the well-being of the bridge, proper

connections must be made between all parts of the bridge and catwalk. For the catwalk,

connecting the support beams to the piles is the primary concern. Using 1 inch diameter

galvanized A325 steel bolts, the following connection will be provided for the pile. In concrete

piles, the anchor bolts can be embedded or drilled into the pile. The two planks used to make the

supporting beam will be connected to the pile, shown in Figure 16, then connected once more 16

inches apart on each side, with the ends of the beams being 21 inches from the center of each

pile. Another set of bolts will connect the planks 7 inches from the end of the planks, as shown

below (Figure 17) (FEMA 2005).

1.5’ 19’ 19’

Supports spaced 25’ along length of catwalk

Figure 16: Diagram showing how wooden beam connects to piles.

Figure 17: Reference for splicing wooden beams and layout of bolts at connection to pile.

The bolts will go through the support beam and the pile. A notch will be cut into each pile to

ensure proper bearing, as shown in Figure 18. The beam should ideally have no gaps between it

and the pile, and should allow for 4 inches from the top of the pile and beam to the centerline of

the top bolt. The planks on the deck can simply be nailed or screwed into each beam to provide

connection (FEMA 2005).

Figure 18: Standard wooden pile connection cross-section

The truss bridge would have connections that are standard at Contech. These details use three

bearing plates held under each corner with two anchor bolts connected with a washer and two

nuts (Figure 19 and 21) (Contech 2012).

Figure 19: Truss bridge bearing connection to abutment.

The truss members will be held together in a splicing method shown in Figure 20.

Figure 20: Truss member spliced connections

The deck will also be made of planks, and be screwed into the stringers and bottom chords of the

bridge, seen in Figure 21.

Figure 21: Cross section of bearing at abutments and connection details of the deck.

Rip Rap

With the construction of the catwalk and bridge the current stream situation needs to be remedied

regarding the current erosion issues. The main concern would be the side of the levee that is

eroding away due to the spring perpendicular to it. This is shown in Figure 3. Rip rap would be a

good option to mitigate erosion while also being a cost-effective option. Accounting for the 100-

year storm worst-case scenario as mentioned earlier, the recommended size of rip rap required

for the stream would be 10". This was calculated using the equation in Figure 22.

Figure 22: Rip Rap Size Formula

For the levee erosion area, approximately 20 tons of rip rap would be required to properly fill the

area. Per the NRCS design guide on rip rap, the slope for 10"+ diameter rip rap would have to be

32 degrees (NRCS Engineering). This would require that the current levee area that has eroded to

be regraded to the specified slope. The proper depth of rip rap to ensure longevity of the project

would be 18" deep. A full side view of the rip rap can be seen in Figure 23.

Figure 23: To-Scale Side View of Levee Rip Rap

For the stream bed underneath the current bridge, erosion is an issue as well. To counter-act the

erosion the inclusion of a step pool would be recommended to slow down the flow of water

through that area. Figure 24 shows how the step pools would look and work in the proposed

location. The current proposal would be to add rip rap for a 100 ft stretch upstream of where the

bridge is located across the entire width of the current stream. For this project, approximately 90

tons of rip rap would be required to construct the step pools.

Figure 24: Proposed Step Pool Implementation

Cost Analysis

For this project, there is a budget of $250,000. Some of the considerations in the cost analysis

would be considered “optional” in the replacement of the bridge system. Muddy Consultants is

always looking to provide the best design work for each client, which is why extra options are

included within the cost analysis. This way, the client can construct exactly what they want

depending on how much they are willing to spend.

Table 2: Cost Breakdown for Each Project Component

Project Cost ($)

Bridge 65,000

Catwalk 144,000

Rip Rap 4,950

The first cost analysis that needs to be performed would be for the 100 foot bridge itself. The

current suggestion is for a single span bridge to be placed at the same height as the levee. This

would allow the citizens and park visitor to view the flood from above as is highly recommended

by the client. The cost for this bridge can be split up between materials costs. Two W14X22 steel

I beam girders for the bridge would be $4,000 (Midwest Steel and Aluminum). For the decking,

treated lumber at an 8 foot width would cost $1,000 for the 100 foot span (Home Depot). The

MSE walls would cost $10,200 (FDOT Structures Manual). This would bring the total cost for

the bridge up to $15,200 for the materials. With labor included, this would raise the cost to

around $65,000 (Excel Bridge). The catwalk and the bridge would fall under the $250,000

budget. The client could then decide to construct other suggestions such as step pools with the

remaining budget.

A catwalk would be necessary to span the floodplain to reach the new, elevated bridge. Timber

pilings would be the cheaper option, but they would only give a design life of around 17 to 30

years. For the concrete pilings, it would cost $144,000 for the entire length of the catwalk, which

includes the labor cost (Permatrak).

The Muddy Consultants would add rip rap to the levee where it is currently eroding and also

underneath the new bridge. There is a section of the levee near the bridge that has been eroded

by a nearby spring waterway and must be fixed. This procedure is not an optional expenditure as

this is an issue that needs to be fixed before it gets worse and collapses the levee. The rip rap

needed for the levee erosion prevention would cost about $850 (Wireless Estimator) for the rock

to be shipped to the location. Rip rap with 10”+ diameters would be required for this project due

to the amount of water passing through. Step pools under the bridge would be another area to rip

rap since it is experiencing erosion as well. However, this area is not currently a large issue and

the expense for this certain project could be considered non-necessary. It could still be beneficial

to slow the water down in this area though, through the use of step pools. For a 100 foot length

of step pools, it would cost about $4,100 (Wireless Estimator).

References

123 Remodeling. (2015). “5 Decking Materials – costs, benefits and life-span.”

<http://123remodeling.com/decking-materials/> (Apr. 22, 2018).

AASHTO (2009). "LRFD Guide Specifications for the Design of Pedestrian Bridges",

http://www.wsdot.wa.gov/eesc/bridge/designmemos/11-2009.pdf (4/11/18)

Bourdeau, P. & Zevgolis, I (2007). “Mechanically Stabilized Earth Wall Abutments for Bridge

Support”

Coduto, Donald P. (1999). Geotechnical Engineering: Principles and Practices. Upper Saddle

River, NJ: Prentice Hall.

Concrete Network, https://www.concretenetwork.com/concrete-prices.html (4/22/18)

Contech (2012). "Pedestrian Truss Bridge Details",

http://www.conteches.com/DesktopModules/Bring2mind/DMX/Download.aspx?PortalId=0&Ent

ryId=1890 (4/11/18)

Excel Bridge, http://www.excelbridge.com/for-owners/cost (4/22/18)

FEMA (2005). "Wood Pile-to-Beam Connections", https://www.fema.gov/media-library-

data/20130726-1536-20490-3614/fema499_3_3.pdf (4/22/18)

FDOT Structures Manual,

http://www.fdot.gov/structures/structuresmanual/2007january/DesignGuidelines/SDG9.2CostEst

imatingProcess.htm (4/21/18)

Home Depot, https://www.homedepot.com (4/21/18)

NOAA

https://hdsc.nws.noaa.gov/hdsc/pfds/ (4/21/18)

NRCS Manual

https://www.nrcs.usda.gov/wps/portal/nrcs/site/national/home/ (4/21/18)

Midwest Steel and Aluminum,

https://www.midweststeelsupply.com/store/hotrollsteelbeam (4/21/18)

Permatrak, https://www.permatrak.com/news-events/bid/97419/boardwalk-construction-

estimates-how-much-does-a-boardwalk-cost (4/22/18)

NRCS Engineering,

https://www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/nrcs144p2_025594.pdf (4/22/18)

Wireless Estimator, http://wirelessestimator.com/content/industryinfo/702 (4/22/18)

Corus Construction and Industrial. (2005). ‘Weathering Steel Bridges’.

http://resource.npl.co.uk/docs/science_technology/materials/life_management_of_materials/publ

ications/online_guides/pdf/weathering_steel_bridges.pdf (Apr. 20, 2018).

American Galvanizers Association. (2018). ‘Hot-Dip Galvanized Steel vs. Weathering Steel’.

https://galvanizeit.org/uploads/publications/Galvanized_Steel_vs_Weathering_Steel.pdf (Mar.

17, 2018).

Helipress. (2017). ‘The top 5 heavy-lift helicopters in the world’.

http://www.helipress.net/schede-708-the_top_5_heavy_lift_helicopters_video (Apr. 21, 2018).

Appendix

Hydrology Calculations

CN=86

Ia/P=0.04

Ia= 0.326

Avg Slope= 0.2%

r = a/pw

a = 17ft*4ft = 68ft^2

pw = 17ft

r = 4

s = 0.2

n = (Engineeringtoolbox.com) Floodplains Trees = 0.15

V= up to 11ft/s

Unit peak Discharge (graphical method) = 450 csm/in

WQv= P * I

Rv = 0.05 + (0.009*15%)

Rv= 0.185

P = 7.61in

WQv= 1.4

Qp = qu*A*WQv

Qp = 767 cfs Over entire watershed

CONTECH Prefabricated Bridge Cost Estimate