Brian Brenner, Professor of the Practice, Tufts University
One of the first steps in designing a new bridge is preparation of a bridge type study. This conceptual design compares different alternatives for a new bridge and provides recommendations on what type to advance in subsequent preliminary and final design. For MassDOT, a bridge type study follows the requirements and format of a “Bridge Type Selection Worksheet.” The requirements for this report are described in the MassDOT LRFD Bridge Design Manual.
A team of experienced bridge engineers can develop conceptual designs and draft a report, but how about Artificial Intelligence? I was curious, so I asked ChatGPT. This AI engine works by…. I have no idea how it works. Hopefully someone else can provide an explanation. Similar to Google, you can ask ChatGPT questions. Unlike Google which provides a list of references, ChatGPT prepares a more detailed answer to your question, in the form of seemingly coherent sentences and paragraphs. The responses are typically given to you in seconds after posing a question.
To give this a go, I asked ChatGPT the following:
“Prepare a bridge alternatives analysis for a new bridge to be designed and built. It is to span 60 feet over a small river, carrying two lanes of traffic and two sidewalks.”
ChatGPT thought about it (assuming AI engines “think”) for a few moments, and then provided the following response:
The project involves the design and construction of a new bridge spanning a small river with a clear span of 60 feet. The bridge is intended to accommodate two lanes of traffic and two sidewalks, providing a safe and efficient crossing for both vehicles and pedestrians. To ensure the success of this project, a comprehensive alternatives analysis must be conducted to evaluate various design options and select the most suitable bridge type.
Alternative 1: Concrete Girder Bridge
Alternative 2: Steel Truss Bridge
Alternative 3: Timber Arch Bridge
Alternative 4: Composite Fiber-Reinforced Bridge
Evaluation and Recommendation:
The choice of bridge type should be based on a comprehensive evaluation of the project's specific requirements and constraints, including budget, construction schedule, maintenance resources, and aesthetic preferences.
Based on the analysis:
Ultimately, the choice of bridge type should align with the project's priorities. Considering factors such as budget, maintenance capabilities, and aesthetic preferences, it is recommended to proceed with a detailed engineering and cost analysis for the Composite Fiber-Reinforced Bridge as it offers a promising combination of durability and low maintenance, which can be advantageous for a long-term infrastructure project.
Here are a few comments on ChatGPT’s work:
The “draft” type study is coherent, but the choices of alternatives don’t necessarily make sense in the context of practical bridge design. Also, ChatGPT’s report is pretty generic and does not fit any format requirements that a particular bridge owner such as MassDOT would require.
On the other hand, it may be possible to “train” ChatGPT or AI engines to drill down based on specific requirements and areas of knowledge. So, for example, if I had worded the initial question more tightly and provided specific MassDOT guidelines for how the report was to be formatted, perhaps the response would be closer to the mark.
In that vein, it may be possible for AI ultimately to provide credible initial drafts of formatted reports. Actual human engineers would still be needed to provide expertise, review and polish for the final report and recommendations. With this approach, AI might be used to prepare a lot of the initial “leg” work to get the document started, instead of the need to start from scratch each time. Conceptual design, after all, is a synthesis of existing knowledge without providing much detailed engineering. This is something that AI approaches seemingly can contribute to. It is not that different from the process of organizing existing bridge data in support of a conceptual design.
So, it does seem that even with AI, human bridge engineers would still be needed to contribute to the designs. For now.
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