Fermilab LInC Online

The Bridges of Adams County

Scenario-2

Introduction:

Mr. Randall Dunkin is the Principles of Technology Instructor at the Ohio Valley Vocational School. Located in Adams County, the school's rural setting is within minutes of both the Ohio River and the Brush Creek Watershed. Recognized as one of Ohio's most ecologically important watersheds, the beauty and diversity of wildlife around Brush Creek stands in stark contrast to the devastation and loss of human and animal life that is often experienced by this unique habitat The damage caused to the county's infrastructure and private homes coming from these relatively common but unpredictable flash floods is so large as to be nearly unfathomable to this poverty-stricken region.

Last year, the stream known as Brush Creek along with the Ohio River that serves as our southern boundary wreaked havoc on our county community to the tune of tens of millions of dollars. FEMA helped to replace some of the structural damage, but the loss of life was unreplacable. We live with the understanding that we are annually at risk for the same kind of destruction we experienced in the Spring of 1997.

One of the largest and perhaps most prominent group of structures that continue to serve as reminders of the tragic flood of 1997 are our county's bridges. Noting this destruction and the concomitant roadblocks to travel by county roads still in existence from the flood, Mr. Dunkin is using the damage to the bridges as an opportunity to engage his junior Carpentry students in an authentic, collaborative learning opportunity which will allow them to learn about the principles of engineering through the design, construction and testing of their own model bridges.
Assisted by two different but mutually supportive computer software programs, the Internet, and the principles of technology, the junior Carpentry students will design and build their own model bridges. As our community worked together to recuperate from the flood's effects, the Carpentry students will work cooperatively to design and build their best bridge. Mr. Dunkin's most desired outcome after the learning of skills and the garnering of knowledge by students is that the information gained from this project and the actual bridge models built can be shared with the community in such a way as to beneficially provide input into the process of rebuilding our community's infrastructure.

Students who participate in this project will demonstrate the ability to:

1. utilize the process of science
2. apply their knowledge of bridge design to a real-world problem.

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Scenario:

In an effort to enhance the math and science skills, science process skills and collaborative work skills needed by today's citizen, the teacher introduces the Junior Carpentry class to a problem that relates to their own experience: bridge building and design. Day 1 finds the teacher introducing the idea of bridge building and the design process to the class. General class discussion of personal experiences with bridges and bridge design is entertained. The video "The Flood of '97" is shown to the class, which depicts the Spring flood of Brush Creek and the Ohio River that caused millions of dollars worth of damage and loss of human and animal lives in their home county of Adams. Students are already grouped heterogeneously in teams of four students with respect to ability level, collaborative work skills and computer skills. As the film is shown, students comment on certain buildings and bridges viewed on the film as being in their neighborhood or no longer in existence due to the flood. Students seem interested in the damage that the flood has created and in the emergency measures used to save lives and property immediately after the flood dissipates. On student asks if the teacher has additional films that show the cleanup and safety measures that were used. The teacher says that other videos about the flood will be brought in tomorrow and that we will continue to pursue the topic of bridges and their design.

On Day 2 the teacher shows another video to the class about FEMA's role in the flood damage and a second video which depicts the Tacoma Narrows Bridge being torn apart in high winds. The video is a home movie, so it is not as elegant as the flood video shown on Day 1. The students are amazed at watching the bridge being destroyed and several of them note that our closest bridge across the Ohio River into Kentucky is a bridge with a design not too unlike the Tacoma Narrows Bridge. The class asks to see the video of the Tacoma Narrows Bridge being torn down again so as to get a better understanding of what happened. This time they notice that there are automobiles still parked on the bridge as it falls into the water. The students are asked at this time to brainstorm in their groups to come up with reasons for why many of our local bridges were destroyed so easily in the flood of '97. After several minutes of discussion in their cooperative groups, one group leader offers the explanation that our bridges were built with inexpensive materials because our county could not afford anything better. Another group spokesperson offers that the bridges destroyed in our county by the flood were very old and not in good repair. A third group believes that the bridges were built using the wrong design. The teacher then asks the class to decide which answer is the best one for explaining why the floodwaters caused so many of our bridges to destruct. No consensus is reached. At this time, the teacher informs the class that the County Engineer, Mr. Wallingford, will be talking with them and the Drafting class tomorrow about why the bridges were destroyed by the flood. The teacher instructs each student to consider the questions they want answered by Mr. Wallingford on the next day.

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Mr. Wallingford addresses the Drafting class and the Carpentry class together in the multimedia room. He first presents a slide show of the damage done by the flood, which depicts houses, business buildings, and automobiles destroyed. The second half of the slides addresses the bridges of Adams County, and includes the collapsed bridges as well as the ones filled with debris that the flood left behind. Mr. Wallingford informs the students that there were contributing factors to the damage done to the bridges by the flood, and that these contributing factors stem from the changing demographics of Adams County. As the county increases its population, more land is cleared for housing developments which increases the water run-off in areas which have bridges. This increased run-off in the bridge areas, he states, undercuts the bridges and weakens them making them more susceptible to damage or destruction by floodwaters. He says that the advanced age of the bridges combined with the increase in bridge traffic are also factors in the bridge failures, regardless of floodwaters. Mr. Wallingford ends his presentation by inviting the students to visit his office and to take a field trip with him to inspect firsthand many of the bridges of Adams County for themselves. The students are excited about the trip, but are informed by their teacher that all emergency medical forms must be on file before they will be allowed to take the field trip to the bridges. The teacher is also excited about the trip because he has never experienced bridges from an engineer's practical standpoint.

Day 4 is an exciting day for the students of the Drafting and Carpentry classes, as they board the school bus to Mr. Wallingford's office. Engineer Wallingford first gives them a tour of his office, including the maps and blueprints of the various bridges that are currently considered a risk. He shows the class a technical report on the bridge near the Vocational School that many of the students cross each day on their way to school. The report indicates that this particular bridge needs repair badly. The students are beginning to talk about alternate routes to school away from this bridge. From this location, the students and teachers again board the bus to visit one of the collapsed bridges from the flood. Mr. Wallingford allows the students to inspect the piers and the trusses which are mangled but still looking strong. Some of the students cannot believe that water could do this much damage to concrete and steel. Back on the bus again, the class is shuttled a few miles down the road to another bridge across Brush Creek. As the students begin to inspect the bridge, it shows no sign of damage or disrepair. Mr. Wallingford then takes them under the bridge to show them the cracks in the concrete that are forming, and points out where some of the concrete has fallen out of the cracked concrete onto the ground. A student asks how often the bridges are inspected, and Mr. Wallingford states that there is a regular inspection protocol followed by the county. Another student asks how much it would cost to replace this bridge, and Mr. Wallingford replies that it would cost approximately $100,000 to replace what looks to be a very small bridge across a small creek. At this point, the field trip is over and the students are taken back to the school. The trip has taken nearly an entire school day, but the students have pictures taken with their digital camera that they can use for their project and to publish on the project Web site.

On Day 5, the students in Drafting and Carpentry are asked to discuss the field trip in an open forum and to entertain possible designs that they would suggest for the bridges that would replace the damaged or destroyed bridges of our county. They are directed to the bridge project student page for Web sites and a list of resources that deal with bridges and bridge design. Working in teams of two at this point, each student is directed to begin the process of developing a research paper of 400-500 words due one week from today in which the history of bridges, the components of bridge strength, and a possible bridge design or two that they might like to use is included in the report. A minimum of three sources is to be used to write the paper. Students are informed that the report is to be typed using a word processing software program provided in the computer lab, and that spelling and grammar will be graded even though it is a science class. A few groans are heard from the poorer spellers, who are then reminded of the spell check feature on the software program by the teacher. Continuing the process of assessment which was introduced at the beginning of the year, students are reminded to submit their day-to-day assessment diary, their weekly group process assessment and their individual work habits assessment forms before leaving the class. Each week, the assessments are submitted to the teacher as a matter of routine.

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Day 6, 7 and 8 will have the students visiting some of the Web sites provided them at the student page of the bridge project in order to gain information (http://www.cwru.edu/cse/eciv/bridge.html) for their bridge report. Some of the students are at work visiting sites on the Internet, some are sending e-mail to engineers and architects for tips on building bridges while a few others have chosen to use the bridge building and photo books donated by Mr. Wallingford to the school. All students are expected to use the Internet as a part of their information gathering process, and to record the sites visited and the e-mail addresses procured so that they will have a record of their efforts. This information can also later be used to create a bibliography page for the bridge project Web site. On Day 9 of the project, the teacher provides students with a look at his own model bridge, which he made using only balsa wood and wood glue. With the weight of the bridge being only 511 grams, the teacher says that his bridge can support his weight without being destroyed. Most of the students do not believe that statement, so the teacher slowly and carefully puts one foot on the bridge and then takes the other foot away from the floor so that the bridge is supporting his entire weight of 220 pounds. The teacher then explains to them that there have been many bridges made of the same materials that held much more weight than his bridge is capable of doing. The students ask how that can be accomplished, and the teacher introduces a balsa wood triangle. This, he tells them, is one of the secrets. The teacher instructs the class to be aware of the triangle shape in the bridges that they are choosing as their favorites. The teacher then reminds the class that tomorrow is the due date for the bridge report and also for the assessment sheets of that week.

Day 10 arrives and with it come the written reports from students about bridge history, strength and design. The teacher informs the students that the reports will be assessed by Day 11 and returned to them so that the reports can be used for upcoming work on their bridges. The Case Western Reserve University bridge building competition video is presented to the students, and the rules for bridge building competitions are given out. During this class period, the teacher addresses an old tale that has been around for as long as he can remember about a worker on the Maysville, Kentucky bridge being murdered and thrown into a concrete pier supporting the bridge. Of course, no body was ever found supposedly because it was inside the concrete pier. The teacher then shares an old nursery rhyme with his high school juniors, and as he sings the first verse they exchange glances and laugh. "London Bridge is falling down, falling down, falling down, London Bridge is falling down, my fair lady." Continuing with the song, the next verse is not as familiar: "Set a man to watch all night, watch all night, watch all night, set a man to watch all night, my fair lady." The teacher explains that people once felt that a bridge required a human spirit. They sometimes buried a human sacrifice in the bridge's foundation so that the spirit could "watch all night". According to the teacher, although we no longer sacrifice a night watchman when we build a bridge, the myth lives on in modern times.

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On the eleventh day of the project, the teacher returns the bridge reports to the students and directs the students to sketch their bridge on plain paper, including all measurements within the dimensional envelope, a side view, a roadbed with an opening in the center, a top view, and end view. The teacher instructs them to take their time and be careful in their sketches. This activity takes all of this day and nearly all of Day 12. Some of the student teams express their opinion that there should be a category for a winning bridge that does not depend on the strength capabilities of the bridge, but on the aesthetic properties of the design. A meeting with the Drafting class leads to developing a second class of competitions based on the aesthetic qualities of the bridge. A committee of two Drafting students and two Carpentry students is chosen by the students to contact judges for this new competition.

Once the sketch is approved by the teacher, the student is instructed to transfer the sketches to graph paper. The student should show the actual width of each piece with a double line, and double check all measurements for proper dimensions. When this is accomplished, the team will receive their materials. The bridge should be constructed so that both sides are built first, then fit roadbed pieces between sides, and finally fit the top pieces between the sides. Inspect the model bridge for places that may need more glue or strengthening, and then label your bridge. To prepare for construction, begin using the bridge building design and testing software on the computer. By designing their bridges using the bridge software, the student can analyze the bridge for weak components and for strength in a different way than visual inspection. Quickly it is discovered by most students that the process of design is not a random activity, but a science based on specific principles. All concerned realize early on that the bridge testing software allows tremendous savings in materials and costs, thereby simulating the value of the same kinds of computer simulations in real life by design engineers. Our school has limited funds, and the bridge testing software program allows us to compete favorably with those schools who can afford nearly unlimited amounts of materials. Testing of the bridge designs by the software programs will take the most of the next two weeks, as the various members of the bridge design are tested, improved or removed and redesigned for ever increasing strength-to-weight ratios. Students save their best designs and begin work to improve them as soon as class begins on the next day. On Day 13, the triangle is again discussed. This time, students make a triangle, a square, and a pentagon out of balsa wood and wood glue. The members of each of these polygons are of equal length. On Day 14 after the glue has dried, the three polygons are manually tested for strength characteristics by the students. It is hoped that the student will discover the relative nondistortability of the triangle as compared to the other two polygons. Hence, a triangle can support heavy loads with its relatively small weight. Each week will see the end of the week assessments handed to the teacher by every student.

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On day 21 of the project, each bridge building team will receive final approval of their software tested design, and the requested materials are handed to the student by the teacher. The teacher gives a safety talk regarding the tools used to cut the balsa wood, and a checklist is given to each team member. A video library of instructional tapes which discuss tension, compression and torsion in bridges is made available for students. Some of the students will explore the tension, compression and torsion values of the balsa wood they must use to create their bridges. Others will be experimenting with different angles to be used on the alignment of the members in the model bridge being built. A few are evaluating another alternative: the amount of glue that should be used for maximum strength of the bond with minimum weight added to the structure. The teacher notices that there are complaints coming from one of the bridge building teams against another team in the same vicinity of the room. The complaint is that one team is stealing the ideas of another team. When informed of this "treachery" by the offended party, the teacher discussed the realities of working in a world of corporate spies and cautioned everyone to hold their ideas a little closer to their heart. The next four weeks are used primarily for construction of the model bridge by the student teams. Students from other schools who have been a part of model bridge building are being contacted by e-mail from their Web sites for information and collaboration on bridge designs by the Carpentry students. The Carpentry Instructor and the Principles of Technology Instructor are both present to answer questions and assist students in the procurement of materials when requested. One team experiments with the effect that soaking the balsa wood in water has on the flexibility of the material. Another group is seemingly testing the effect of adding little chips of balsa wood to the bond. After closer inspection by the teacher, it was discovered that this was a ploy by one of the students from the group who had been the victim of espionage earlier in the project. Apparently it was decided by this group that they would not only keep their original bridge design secret, but that they would plant a decoy of worthless design information for the spy group to discover. The humor in all of this is not lost on the teacher or the students who are aware of the ploy. By Day 40 of the project, all bridges should be completed and their pictures taken with the digital camera for the project web site. The completed bridges are displayed at the local Shopping Mall on a Saturday for an afternoon as students discuss and explain their bridge design to passersby.

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At Day 41, the Drafting class and the Carpentry class will meet in competition to determine which of the constructed model bridges will test out to have the largest strength-to-weight ratio. The competition is to be held using the same rules and regulations as the Case Western Reserve University competition, so that our winning bridge design will be ready to compete in the regional competition after the local competition is over. The parents and local media have been invited to the competition, which will take nearly four hours to complete. While the first team randomly chosen to place their bridge under the test bricks gets ready for their bridge to be broken by the increasing weight load, other student teams are scattered about the room making last minute changes and repairs to their bridges before their turn comes for the test. The first bridge reaches its failure point, and the sickening "crack" signals to the team that their bridge has reached the end of its life. The test official calculates the strength-to-ratio measurement for the first bridge, and the rest of the teams have their first measure of what it will take on this day to win. Finally, a winner is declared as the rest of the model bridges rest in pieces at the bottom of large trash cans. These cans were especially chosen for the task so that the scrap balsa could be salvaged for more bridge building in the future . While the strength competition is going on, a second team of judges is at work evaluating the bridges for their aesthetic qualities. The bridge determined to have the most pleasing aesthetics is announced as a winner in its own right.

On day 42, the winning model bridge designs are analyzed by the class to determine the winning characteristics, rebuilt if necessary, and sent to Case Western Reserve University as our school's entry into the regional competition. While only one team can qualify for each category of the competition, a school bus is provided so that both the Drafting students and the Carpentry students can come along to provide support for the team and to reconnoiter for next year's competition.

Near the end of the project, the results of the bridge-building and the final competition are published on our project Web site by the winning team members and a news article for the local paper is also written and submitted. Plans are then discussed for having the entire Carpentry class build two larger scale models of the winning bridges to be installed on campus with the Drafting class creating the blueprints. The Carpentry Instructor assists the class in selecting the proper wood for the project, and the bridge site selection is considered by having the entire class walk the site for visual inspection. Possibilities at this point for the winning bridge designs are several, including the potential for having the Carpentry class construct and sell several of these bridges for ornamentation or utilitarian purposes to community members. Again, it is hoped that information gained from the project will result in authentic contributions from the students involved to the community at large regarding the construction, design and placement of the new bridges that will have to be built to replace what was lost in the flood of '97.

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