Achieving next-generation transportation infrastructure

Policy Perspectives on Infrastructure MIT School of Architecture and Planning Policy recommendations convened by the MIT Norman B. Leventhal Center for Advanced Urbanism October 2021

Achieving next-generation transportation infrastructure through lifecycle performance assessment, design excellence, and digital fabrication The bridges, roads, and public built environment of the coming decades should minimize environmental and economic costs, enhance the beauty of public space, and incorporate state-of-the-art construction technologies

By John Ochsendorf, Caitlin Mueller, Keith Lee, and Alena Titova.

Summary

The bridges, highways, and dedicated public transportation structures that millions of Americans rely on each day are at a critical breaking point. Decades of neglect and delayed maintenance have left the nation’s transportation infrastructure in a vulnerable state of frequent failure, causing at best disruptions in trade and commute times, and at worst, catastrophic disaster. Just repairing and replacing thousands of structurally deficient pieces of infrastructure is not enough, we must update the ways this overhaul will be designed, engineered, and constructed.

In modernizing our nation’s bridges, highways, and rail systems, federal programs should require thinking beyond initial upfront costs, and consider their long-term effects on the overall economy and the environment. We propose that the federal government create, and encourage the use of a unified set of tools and databases to evaluate the environmental and economic long-term costs of new designs. Lifecycle performance analysis (LCPA) and lifecycle environmental analysis (LCEA) tools would provide a quantifiable measure of the long-term impact of an existing or proposed structure. By making greater use of existing federal databases and providing incentives for participation from the private sector, the federal government can increase the quality and widespread adoption of lifecycle performance measurement tools.

Scope of Problem

Transportation infrastructure contributes to greenhouse gas emissions in two ways: the emissions from the fossil fuel burning vehicles for which they are primarily designed, as well as the embodied carbon emissions from the structures themselves – the extensive network of bridges, highways, gantries, and other ancillary structures (that support lighting, signage, and toll collection). Embodied carbon includes the greenhouse gas emissions associated with material extraction, transportation, processing, manufacturing, and assembly, and can be quantified for construction materials via lifecycle assessment processes.

Architects and engineers increasingly use embodied carbon as a performance measure in design decisions. This should become standard procedure for transportation infrastructure. Pathways to reduce embodied carbon include using alternative, less carbon-intensive materials (e.g. timber), re-using or upcycling available construction material from existing construction, and using efficient design concepts that require less material to achieve structural tasks. The cost of infrastructure should no longer be restricted to static financial analyses. Instead, we should consider the entire lifecycle from initial material sourcing to maintenance and eventual decommissioning.

The existing practices and methods of infrastructure construction are outdated. While developments in computational design, optimization, and manufacturing have led to major advances in industries such as consumer electronics, opportunities to apply similar capabilities for large-scale construction remain underexplored. This is true around the world, but especially in the United States. While the governments of Switzerland and Germany have begun to provide grants for research and development in automated construction and digital fabrication, the United States lags behind.

Technologies such as large-scale 3D printing, robotic assembly of structures, and Computer Numerical Control (CNC) machining represent the future of construction generally, and have the potential to transform how American infrastructure is built in the next decade. The adoption of contemporary infrastructure design benchmarks and an integration of aesthetic considerations in the design process will also require modernization of manufacturing and construction technologies, as well as the additional training for skilled laborers.

While the U.S. government has invoked Design Excellence as a standard in projects such as federal buildings, there is no federally backed push to achieve Design Excellence in transportation infrastructure. The General Services Administration (GSA) has defined Design Excellence guiding

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principles for federal architecture where buildings must be efficient and economical while also providing “visual testimony to the dignity, enterprise vigor, and the stability of the American Government” with special attention to the US’ regional influences.1 We take inspiration from the GSA to create Design Excellence principles specific to transportation infrastructure. An infrastructure project that achieves Design Excellence must minimize resource consumption and maximize performance throughout its lifespan by harnessing new building methods and technologies.2 Under these conditions, civil and structural engineers would have the opportunity to leverage their talents to develop innovative solutions that are both high-performing and aesthetically distinctive. While some guidelines for bridge design aesthetics exist3 — detailing color, shape, form, texture, and proportion — they are too prescriptive to be applied across the entire US. Instead, the implementation of design competitions for bridge projects can be used to apply case-specific interpretations of Design Excellence by engineers and architects that can then be evaluated by project stakeholders and through a peer-review conducted by a diverse panel of experts in the field and research.

A structure’s aesthetic value will be determined through its solution to a design problem in a manner that is structurally elegant. Yet structural expression alone is not enough; a visually novel design that consumes an exorbitant amount of material is not an example of Design Excellence.

Recommendations

To achieve Design Excellence in transportation infrastructure, the U.S. needs to develop and adopt two key components: a unified method of evaluating the economic and environmental impact of a design, and the framework for a design competition process to realize these evaluation methods at scale. We provide background and recommendations for each component in the following section.

Development of a Unified Evaluation Tool for Lifecycle Economic and Environmental Performance: To assess the quality and lifecycle implications of varying designs, a standard method of comparison is required. We recommend that the National Institute for Standards and Technology (NIST) and FHWA develop unified evaluation tools for lifecycle performance analysis (LCPA) and lifecycle environmental analysis (LCEA).

Economic performance: The price of a completed structure does not reflect its true end cost: an informed estimate of repair, maintenance, and decommissioning costs provide a more accurate reflection of the quality of a design.

The recent closure of the Hernando de Soto Bridge in Memphis due to the delayed response to a member fracture cost the trucking industry an estimated $2.4M per day4. An accurate understanding of the cost of deferred maintenance and repair during the initial procurement process would incentivize more stringent inspection and repair programs. Further, better initial analysis could alter the design of the bridge itself, resulting for example in a design that includes more redundant structural systems that would not require complete closures in the event of a single member failure. LCPA provides the method of evaluating the cost of these failures and their preventive before a final design is completed.

The importance of LCPA for bridges and other transportation infrastructure has been recognized in the academic, private, and public sectors. In 2017, FHWA released guidance5 and an interpretive handbook6 for state departments of transportation (DOTs) to develop LCPA processes appropriate to their needs. This is a valuable first step but more is needed. First, the guidance emphasizes the owner “Design Excellence Program,” U.S. General Services Administration.

David P. Billington, “A New Tradition: Art in Engineering” in Tower and the Bridge: The New Art of Structural Engineering, 6. Design Excellence definition modified from Billington’s conditions for structural art.

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Office of Bridges and Structures, Aesthetic Guidelines for Bridge Design, Minnesota Department of Transportation, 1995.

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Arkansas Trucking Association.

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US DOT FHWA: using a life cycle planning process to support asset management.

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US DOT FHWA: Using an LCP process to support transportation asset management: a handbook on putting the federal guidance into practice.

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cost of maintenance and repair, but not the significant economic impacts from the disruption to bridge users. Second, and more problematically, the guidance is focused on existing structures. For LCPA to be viable in the design phase of new projects, data must be gathered to provide immediate and accurate projections of long-term costs.

Environmental performance: The environmental impact of transportation infrastructure varies significantly. It is insufficient to simply consider the quantity of building materials consumed; from virgin material extraction to eventual disposal or reuse, energy is consumed and emissions are produced throughout all stages of a structure’s life. Lifecycle environmental analysis (LCEA) provides a normalized, quantifiable measure of the equivalent carbon dioxide emissions embodied in a structure. This value of embodied carbon in a given structure is its environmental cost, one that architects and engineers should minimize.

For an effective and accurate LCEA to be possible, significant data must be continuously recorded to cover the wide variabilities in materials, transportation, and construction methods for a given project in the United States. Although databases and tools currently exist at the departments of Agriculture7, Energy8 and Commerce9, there is no streamlined tool or data extraction method for the primary building materials and construction methods of bridges and highways. By extracting the relevant information from existing federal databases for explicit use in the transportation infrastructure sector, an increasingly informed and focused LCEA could be performed to evaluate the environmental impact of bridges and highways.

Recommendations: We recommend the development of LCPA and LCEA tools to allow state DOTs and other transportation infrastructure owners to better evaluate the true performance and cost of a new structure. The principles and frameworks of these tools exist but lack sufficient data and specialization for the transportation infrastructure sector. In addition, incentives to encourage the private sector to use and contribute to these tools and databases are needed. To address these current limitations, we recommend the following joint actions by NIST and FHWA: 1. Develop a transportation-specific LCPA database of existing bridges and highways to calculate baseline measures of long-term economic performance.

2. Develop a transportation-specific LCEA database by extracting and consolidating relevant information from existing federal databases.

3. Once developed, mandate the use of and contribution to the LCPA/LCEA databases for federally funded projects and when existing infrastructure is evaluated by state DOTs. 4. From the experience gained using LCPA/LCEA, develop benchmark values to evaluate the quality of proposed designs in future procurement processes.

Design Competition Pilot Program: The use of LCPA/LCEA benchmarks to evaluate Design Excellence faces an initial hurdle. The private sector must be willing to collect performance data to create robust benchmarks, but there is little incentive to do so during the initial data collection period. The use of high-profile projects as the early adopters for the competition model can be used to incentivize participation in the LCPA/LCEA data collection process through mandatory reporting to NIST/DOT. We recommend that the “ten most economically significant bridges in the country in need of reconstruction,” as identified in the American Jobs Plan (AJP), be used to pilot a Design Excellence competition model.

Federal LCA Commons.

US Life Cycle Inventory.

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NIST BEES/BIRDS/BIRDS NEST. 7.

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Internationally, competition models for large-scale bridge projects have been successful in generating cost-effective, aesthetically distinctive, and high-performing design. The Swiss model of design competitions in the mid-20th century spurred rapid development and innovations in efficient concrete analysis, design, and construction. Similar approaches in Belgium, Germany, and the Netherlands have resulted in high-performing design systems in thin steel and timber. All such cases have required the concurrent advancement of their manufacturing and construction industries to realize these innovative design concepts. With a competition-based procurement framework, the U.S. has an opportunity to become a global leader in design innovation, structural performance, and modernized skilled labor.

For the bridge pilot program, a variety of leading structural engineering firms should be invited by the DOT and federal design bodies, such as the U.S. Committee for Fine Arts, to compete. A committee of both federally and regionally appointed experts — structural and civil engineers, architects, and researchers/academics — would adjudicate and peer review the entrants’ designs on the basis of LCPA and LCEA values, as well as their aesthetic quality and regional suitability. While there is an overhead cost for compensating the entrants’ initial designs, this cost would be minimal compared to the overall price of construction and maintenance. The pilot program should seek suggestions from the public to ensure that designs address community needs such as bike lanes, lighting, and views. This input would then inform the parameters for the design competition. This, in turn, would stimulate further research and development, creating opportunities for academic partnerships and worker training investment.

Criteria-based allocation of federal funds for transportation infrastructure projects is not novel. Existing programs such as DOT’s INFRA10 and FHWA’s CHBP11 require state DOTs to meet metrics such as overall cost, functionality, and degree of design innovation. These existing grant requirements provide a pathway towards a broader implementation of the Design Excellence competition approach beyond the Ten Bridge pilot program. The experience provided by the Ten Bridge pilot project can inform the revision of these smaller grant programs; the existing criteria can be incrementally amended to adopt principles of Design Excellence, and additional funding can be allocated to implement competitionbased procurement processes.

In addition to landmark bridges, design competitions have the potential to be scaled down for ancillary structures such as pedestrian bridges, luminaries, tunnels, signage and more. Besides individual projects, the competition model has the potential to inform regional projects such as overpass bridges that can be bundled together – based on similar dimensions, soil conditions, and other requirements — under a single winning design.

Conclusion

1. With the development of transportation infrastructure-specific LCPA/LCEA tools, the U.S. Department of Transportation should directly fund the design competition approach with Design Excellence metrics for the AJP-identified “10 most economically significant bridges” in need of replacement.

2. Through legislation or agency action, the Department of Transportation should establish a committee to develop infrastructure-specific Design Excellence criteria for the AJP pilot bridge competition.

3. Congress should increase the funding for existing infrastructure grant programs such as INFRA and FHWA CHBP, and the agencies should experiment with the Design Excellence competition approach as a basis for awarding funding.

Infrastructure for Rebuilding America.

Competitive Highway Bridge Program (CHBP) presently awards funds ($225 million in 2019) to state DOTs with low population densities to fund highway bridge replacement and rehabilitation

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About the Authors

John Ochsendorf Class of 1942 Professor, Professor of Architecture and Civil and Environmental Engineering, MIT Department of Architecture, MIT Department of Civil and Environmental Engineering, jao@mit.edu Caitlin Mueller Associate Professor of Building Technology, MIT Department of Architecture, caitlinm@mit.edu Keith Lee, PhD student, MIT Department of Architecture, keithjl@mit.edu Alena Titova, MArch student, MIT Department of Architecture, titova@mit.edu

About policy perspectives on infrastructure

Policy perspectives present responses from faculty in MIT’s School of Architecture and Planning to the American Jobs Plan.

The effort was convened by the MIT Norman B. Leventhal Center for Advanced Urbanism.

MIT School of Architecture and Planning sap.mit.edu At the MIT School of Architecture and Planning (SA+P), we believe that humanity’s toughest problems occupy the same ground as their solutions: the space between people and their environment. This is our territory. From the day MIT opened its doors and introduced Course 4 as the nation’s first academic program in architecture, our faculty, students, and alumni have explored the human landscape to discover—and deliver—better futures.

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MIT Norman B. Leventhal Center for Advanced Urbanism lcau.mit.edu Urban environments constitute one of the most complex societal challenges of today’s world. The LCAU seeks to drive collaborative, interdisciplinary research focused on the design and planning of large-scale, complex, future metropolitan environments, to advance urban scholarship and practice that makes cities more equitable, sustainable, and resilient by design.