It’s tough to choose the best wholesale transportation broker when everyone says they’re the one! And you wouldn’t seek out a baker to fix your car or a pilot to build your house – so why use a generalist when you need a specialist? For more than 30 years, TAU has helped place insurance risks specifically in this arena.
This is our space.

Unmatched Experience and Knowledge

Our team has expertise in every aspect of specialty transportation insurance. From trucking cargo to hazardous material, each member of our team has a deep understanding of the products, services, and markets related to these specialized areas.
You are in the right place.
At TAU, transportation is our sole focus – and has been for over 30 years. Our principals and underwriters have over 80 years of combined experience dedicated to the automotive industry, which has earned us a well-respected reputation in the transportation market.
This recognition has opened global channels with leading insurance carriers, allowing us to deliver competitive options from a wide variety of markets for North American commercial auto liability, auto physical damage and motor truck cargo insurance.
With an innovative mindset, TAU has a distinctive approach to management that gives our underwriters more flexibility and authority – and as a result, enables them to provide the highest level of care to our clients.
We also don’t work with the masses – we look for retailers who are committed to transportation insurance and value long-term relationships. This discernment allows us to spend more time solving the complex challenges our retail partners face.
So, if you’re looking for fast, accurate, and competitive transportation insurance quotes from knowledgeable specialists who are also great people – you’ve found the solution!
The time is now. Reach out today for an appointment consideration.
Consider TAU for expertise on the following coverages:
Commercial Auto Liability Insurance
Commercial Excess Auto Liability Insurance
Commercial Auto Physical Damage Insurance
Motor Truck Cargo Insurance
Excess Motor Truck Cargo Insurance
Dealers Open Lot Insurance
Garage Keepers Legal Liability Insurance
Non-Trucking Liability Insurance
Excess Terminal Insurance
Business Auto


Colby Waltenburg

Colby Waltenburg, President of TAU, has over 25 years of experience in Property & Casualty wholesale brokerage management. His specific expertise is in underwriting and placing transportation business, which is what led him to join Transatlantic Underwriters (TAU), where he continues doing what he loves most. Colby brought his strong relationships with insurance carriers and vast transportation knowledge to the company, and truly enjoys solving the puzzle of a challenging risk.

When he’s not busy at work, Colby enjoys spending time with his five children, who are all homeschooled by his amazing wife, Kristen. He also enjoys playing soccer and other sports when off the clock, and he’s a HUGE Star Wars fanatic.
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Donna Smith, Chief Financial Officer (CFO) for TAU, has over 30 years of experience in both U.S. and international insurance markets. Her strong financial management and operations expertise aids her in managing all finance, accounting, operational and administrative functions at the company. Donna employs a customer-motivated philosophy in collaboration with the management team, which has set the strategic vision and goals to achieve significant growth and outstanding customer satisfaction. Prior to joining TAU in 2019, Donna served as CFO at Coastal Brokers for 28 years.

Donna is an avid Auburn Tigers fan and enjoys cheering on her team when she’s not crunching numbers. War Eagle! She also enjoys traveling, being out on the lake, tailgating and spending time with family and friends.
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Chief Financial Officer


Vice President
Vice President Cheryl Hartz is a self-professed “Guideline-Geek” with over 25 years of industry experience. Cheryl rose quickly, climbing the ranks from file clerk to underwriter as she learned the ins and outs of the business – gaining vast knowledge that she applies to every risk that crosses her desk. An expert in all things Transportation E&S Underwriting, Cheryl has created long-standing relationships with her agents, who have many options in this industry but choose to partner with TAU and Cheryl due to honesty, integrity and transparency.

Cheryl and her husband Steve are currently enjoying raising their youngest son, Oliver. Cheryl enjoys family, church, spending time outdoors, a great cup of coffee and visiting her six grandkids!
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Angela Harrison is an experienced underwriting professional in the Property & Casualty insurance industry with more than 20 years of experience. She began her insurance career underwriting and managing an expansive fleet book, in addition to a large drive-away book of business. In 2018, Angela worked to develop a major fleet product, leading the mid-fleet team to write over $90M in direct written premium. To this day, her specialty remains focused on fleet transportation risks, including trucking, business, and public auto.

Angela loves spending her free time with her three adult children, friends and husband, Michael. She loves to explore by traveling to new places, trying new restaurants and venturing near and far. Angela is also a huge Buffalo Bills fan! #billsmafia
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Senior Fleet Underwriter


Shannon Nauta has been with TAU since 2019 and has over 20 years of insurance experience, beginning on the retail agency side and transitioning to wholesale approximately 15 years ago. She truly enjoys the underwriting process and providing prompt service to her agents, with whom she has forged valuable relationships over the years.

When she’s not helping her agents, Shannon enjoys spending time with her husband and daughters. As an empty nester, she and her husband are always in search of weekend adventures or planning their next vacation.
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Karolyn Karras, Claims Administrator and Renewal Underwriter, has over 30 years of experience in the insurance marketplace with both domestic and foreign facilities. As Claims Administrator, she is responsible for handling and processing claims, acting as a liaison between adjusters, agents and carriers. In her underwriting capacity, Karolyn promotes continued profitable growth with new business and retention of existing business. She appreciates the dual role, which provides her with flexibility and more opportunity to apply her expertise.

In her spare time, Karolyn enjoys spending time with family and friends, getting away with her husband to the casino and wine tasting, of course.
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Claims Administrator &
Renewal Underwriter



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(800) 297-5536


319 Atlanta Street SE Unit 220
Marietta, GA 30060
(770) 977-5610


3558 Deer Park Drive Suite 106
Stockton CA, 95219
(209) 279-1072
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