Bertha, which claims to be the world's largest diameter TBM, has more than 3,500 followers on Twitter.

Project owners are using social media, such as Twitter, to gain public awareness about their construction work. As such, several tunnel boring machines (TBMs) are carving out some time to share their "observations" with the Twitterverse. We recently held an offline chat with the Tweeting TBMs about their experiences; their answers follow below.

ENR: How do you work Tweeting into your busy project schedule?

@BerthaDigsSR99: It’s a challenge sometimes, but I don’t have much of a choice. Tweeting is requirement of my contract. Fortunately, Twitter’s 140-character limit turns out to be a lifesaver. It’s not like I have to churn out a novel.

@MackenzieTBM: I consider myself a tad introverted, so I defer most of my tweeting time to my colleague, NEORSD mascot @WallyWaterdrop.  My job is to finish my dig and get the Euclid Creek Tunnel ready for flow. But sure, during downtime or maintenance breaks, if I’m inspired, I’ll tap out a tweet or two. There’s so much that people don’t know about the work we do, so if I’m another voice to help share that story, I’m happy to speak out.

@BigAlmatheTBM: Until I get to San Francisco, my biggest problem is technological. I’m on a barge on the Pacific Ocean, and Internet service is spotty out here.

Why do you like Tweeting?

@LadyBirdTBM: I’ve got so much to say. It comes spewing out of me like excavated dirt. Plus, it keeps me in contact with the surface. I’m so alone!

@MomChungtheTBM: Twitter reminds me that I’m part of something bigger than myself (and at 750 tons, I’m pretty big). I’m here in this amazing city, building a tunnel that thousands of people will use every day. But since I’m underground all the time, I don’t get to meet very many San Franciscans. Twitter helps connect me with the people I’m working for and remind me of the reasons why I’m working.

Bertha, as a record-setting TBM, and working on a high-profile project, do you consider yourself a trendsetter?

@BerthaDigsSR99: The fanfare that surrounds this project is fun, but I can’t let it distract me. I'm big for a reason, and it has nothing to do with setting trends. I have an important job to do, a job that I take very seriously. This project isn't about me. It’s about building a tunnel that will replace the viaduct and reshape the SR 99 corridor. I’m just looking forward to doing my part.

How many followers do you have? Are there any notable personalities or anyone you wish were a follower?