By Lt. Col. Stanley P. Rader, D.E., P.E., M.SAME, USAF (Ret.)
Undergraduate engineering programs have a dual responsibility to provide students with both a sound technical education culminating in design competence and the ability to successfully apply this education in the context of real-world engineering projects after graduation. Engineering programs are increasingly turning to project-based learning as a valuable method of achieving these two objectives.
Is it possible to provide undergraduate engineering students with an experience that includes both design from a consulting engineer’s perspective and construction from a contractor’s perspective in one integrated effort? Could such an effort include aspects of public service and civic assistance? The answer, through the lens of the U.S. Air Force Academy’s Civil & Environmental Engineering Department, is a resounding yes.
The project-based learning vehicle used at the Air Force Academy was a year-long collaboration with the U.S. Forest Service to design and construct a replacement pedestrian bridge in the Maroon Bells Wilderness of the central Colorado Rocky Mountains. Col. Greg Rosenmerkel, USAF (Ret.), a Forest Service Engineering Staff Officer and an Air Force Academy graduate, proposed that Civil Engineering students design and construct a 35-ft span pedestrian bridge over West Maroon Creek on one of the most heavily used Forest Service trails in the nation. The Forest Service is sorely underfunded for infrastructure maintenance; Air Force Academy-provided design and construction services would result in significant benefits for the taxpayer and the thousands of visitors per year to this national treasure. A total of 10 Civil Engineering majors and one Operations Research student volunteered to undertake the bridge design and construction project in the fall of 2015. None of the cadets had completed an engineering design course prior to beginning this endeavor.
PLANNING & DESIGN
The Maroon Bells Bridge project presented unique challenges that required the cadets to pay special attention to constructability considerations during design. First, the proposed replacement site was in a designated wilderness area. By statute, use of mechanized equipment and power tools is prohibited in wilderness areas. Therefore, transport of construction materials and equipment could only be accomplished by human effort or pack animals. Actual construction had to be done using unpowered hand tools. The fact that the cadets would be directly impacted by their design decisions provided a priceless learning experience for the aspiring engineers-in-training.
The bridge replacement site was a four-hour drive from the Air Force Academy. Return trips to gather overlooked information would not be feasible. The cadet/faculty design team completed the initial site visit to the Maroon Bells Wilderness location in August. In addition to receiving orientation briefings provided by the Forest Service, the cadets inspected and measured the existing bridge to be replaced, took cross-section measurements, collected soil samples, and completed dynamic cone penetrometer tests. A month later, the advisor and a smaller team, made a second visit to obtain a topographic survey. Using data gathered during the two visits, the cadets began the process of designing the replacement bridge and completing the construction planning process.
UNIFYING DISCIPLINES
The project was valuable as it required the cadets to apply principles and processes taught by each of the Civil & Environmental Engineering Department’s four divisions. The cadets were introduced to geotechnical, environmental, structural and construction engineering theory and methods during the course of the bridge design. They had difficulty determining stream design flows and 100-year flood boundaries for a mountain stream that had not been previously evaluated or mapped. They had to account for a 146-lb/ft2 snow load, knowing it was likely that they would have to carry in the 36-ft long beams designed to support this load over a winding mountain trail.The cadets chose to break into geotechnical, hydrology/hydraulics, and structural teams to complete the respective sub-discipline designs. They also formed a team to complete the required project scheduling, equipment planning and cost estimating duties.
During the project, the cadets had access to a Forest Service bridge engineer as well as Department of Civil & Environmental Engineering faculty members for consultations. The product of nearly two academic semesters of work was a set of pedestrian bridge plans and specifications that were approved by the Forest Service in near-record time, and stamped and signed in accordance with its requirements after consultation with the academy’s legal staff regarding liability considerations.
INTO THE WILDERNESS
Completing design projects on paper has long been a requirement for undergraduate engineering students—actually constructing the design is rare. Of the 11 students who began the project’s planning and design phase, eight were able to spend time in the Maroon Bells Wilderness building the bridge. Construction took place during a three-week span in July and August of 2016. Work days were long, but satisfying. The cadets cut and drilled bridge elements at a location about a mile from the bridge replacement site. The prefabrication site was outside the wilderness boundary, so cadets could use power tools connected to a generator for prefabrication tasks.
The most physically challenging parts of the project were moving the four 36-ft long 500-lb beams from the prefabrication site to the bridge site, getting them across the mountain stream, and setting them in the four steel bearing shoes on each concrete bridge abutment.
There was a powerful sense of accomplishment during the ribbon-cutting ceremony when cadets and Forest Service staff celebrated completing the project under budget and ahead of schedule.
Over a period of two days, it took 18 people, including cadets, Forest Service staff, and Aspen Ski Company volunteers, using cargo straps, to move and set each beam. Bridge diaphragms, deck, posts and handrails then were installed using traditional unpowered hand tools, such as hand saws, brace and bit, hammers and screw drivers. The final requirement of the project was for the cadets to demolish the old pedestrian bridge and carry it out of the wilderness area.
PAYING IT FORWARD
There was a powerful sense of accomplishment during the ribbon-cutting ceremony when cadets and Forest Service staff celebrated completing the project under budget and ahead of schedule. As future Air Force Civil Engineering officers, the cadets will likely encounter joint operations environments in which they will need to coordinate beyond Air Force organizational boundaries and become familiar with sister service or allied nations practices and procedures.
This project provided real-world experience doing just that. The cadets had to dig deep into Forest Service manuals and regulations, and had to adjust to means and methods that did not necessarily match those of the Air Force. The exposure to cross-organizational operations should serve the cadets well once they enter the operational service.
The mission of the Civil & Environmental Engineering Department is to build and maintain nationally accredited undergraduate civil and environmental engineering programs with a clear linkage to the operational Air Force. The project-based learning epitomized in the Maroon Bells Bridge project has contributed powerfully to accomplishment of this mission—both through the theory-to-practice experience and the opportunity for these future leaders to develop and strengthen community service habits. The department plans to leverage this inaugural initiative into a recurring opportunity for its future Air Force Civil Engineering leaders.
Lt. Col. Stanley P. Rader, D.E., P.E., M.SAME, USAF (Ret.), is Associate Professor, Department of Civil & Environmental Engineering, U.S. Air Force Academy; stanley.rader@usafa.edu.
The views expressed in this article are those of the author and do not necessarily reflect the official policy or position of the U.S. Air Force Academy, U.S. Air Force, Department of Defense, or U.S. Government.
[Article first published in the November-December 2017 issue of The Military Engineer.]
