TJKM offers a wide range of services with specialized expertise in transportation planning, traffic operations, freeway and corridor studies, traffic engineering design (including PS&E), intelligent transportation systems (ITS), traffic safety, and multimodal studies. TJKM currently has its headquarters in Pleasanton and offices in San Jose, Santa Rosa, Oakland, Sacramento, and Fresno.

TJKM has been involved in more than 8,000 transportation projects throughout California and Nevada. For more than 40 years, more than 3,500 satisfied clients have entrusted TJKM with their consulting needs. TJKM serves a full range of clients, including municipalities, congestion management agencies, metropolitan planning organizations, Caltrans, transportation agencies, private developers, other consulting firms, and attorneys. Serving both public and private clients, TJKM’s knowledge of municipal frameworks, coupled with their reputation for completing projects on time and within budget, has given us a prominent and respected standing within the industry.

We know the unique requirements, area, and stakeholders, providing insight and expertise that informs a variety of solutions–backed by the resources and perspective of a leading firm. We perform at the local level with the knowledge it takes to clearly communicate. We are experts at presenting complex concepts in terms that every stakeholder can understand.

TJKM is a Certified Disadvantaged Business Enterprise (DBE) and a Small Business Enterprise (SBE) within the State of California.


TJKM was founded by Richard Tammen, Arnold Johnson, Chris Kinzel, and Robert Mimiaga in 1974. The original office was located in Walnut Creek for the first 10 years. In the early 1980s, TJKM moved to Pleasanton and played a substantial role in the planning and development of the Hacienda Business Park, where the company currently maintains its headquarters.

On September 1, 2012, TJKM was acquired by Nayan Amin and Ruta Jariwala. Since then we have expanded our expertise in the field of traffic operations, travel demand modeling, complete streets, and traffic adaptive signal systems to enhance the transportation infrastructure for all modes of transportation. Since 2013, TJKM annual growth has exceeded 35%, with 85% of our business coming from repeat clients. Our repeat business and our dedication to building relationships support our growth and success, and is a testament to our proven ability to exceed our client’s expectations.


Nayan 2

Nayan Amin, TE


Mr. Amin has more than 24 years of both public and private sector experience in transportation planning, traffic impact studies, transportation management plans, construction scheduling, construction area signs, signing and striping, traffic signal coordination, traffic operations, transit priority, traffic signal systems, freeway and arterial management studies, intelligent transportation systems planning, and design and construction oversight. He has developed optimized signal timing plans and implemented them for more than 2,000 traffic signals throughout the United States.

Nayan served as Project Manager for MTC PASS Project for 2010-12 cycles, responsible for development of optimized signal timing plans and implementation for more than 1,000 traffic signals throughout the San Francisco Bay Area. Additionally, he has extensive experience on projects related to transit priority, incident management flush plans, traffic responsive, and traffic adaptive systems. He also specializes in macro and microscopic model development and application for analysis of traffic impacts. His experience also includes multi-modal operations, light rail, bus rapid transit, pedestrians, bicyclists, and traffic safety and operations.

Ruta J.

Ruta Jariwala, TE, PE


Ms. Jariwala has more than 14 years of professional experience in traffic operations, transportation planning, freeway and arterial management studies, signal coordination, traffic signal systems, traffic impact studies / environmental impact reports (EIRs) and intelligent transportation systems planning, design, and construction oversight. She also has experience on projects related to transit priority, incident management flush plans, traffic responsive, and traffic adaptive systems.

She has extensive experience in macro and microscopic model development and application for analysis of traffic operations for express lane studies. Her experience also includes multi-modal operations, light rail, bus rapid transit, pedestrians, and bicycle and traffic safety studies. She has worked on numerous signal coordination projects throughout California, where she was responsible for development and implementation of optimized signal timing plans.


Chris K.

Chris Kinzel, TE, PE

Vice President

TJKM co-founder and current Vice President, Chris Kinzel, served as President for more than two decades. Chris graduated from the University of California at Berkeley with a Master’s degree in Transportation Engineering and also holds a Bachelor’s degree in Civil Engineering from California State University, Fresno. Chris is registered as a civil engineer and as a traffic engineer in California.

As a former municipal engineer, today Chris focuses on working with city and county traffic engineers to determine the most effective strategies for reducing traffic congestion. He has also worked with hundreds of California developers and homebuilders performing development studies and presenting results at various private and public meetings. Chris made numerous presentations to the public and has taught traffic engineering courses for the University of California and the University of Santa Clara. He wrote the Traffic Studies chapter of the Traffic Engineering Handbook, published by Prentice-Hall in 1991.

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Atul Patel, PE, PTOE

Director, ITS & Design

Mr. Patel has more than 20 years of professional experience in both the public and private sector and is a registered Traffic Engineer in California and Civil Engineer in Texas and Arizona. He has served as the Project Manager in the design and implementation for numerous traffic signal designs and Intelligent Transportation Systems communications network projects for public agencies throughout California. Many of the design projects included traffic signal interconnect conduit and cable to the adjacent signals, video detection and video surveillance systems, emergency vehicle preemption systems, fiber optic communication hubs, installation of ADA curb ramps, railroad signal preemption, signing and striping plans, and preparing technical specifications and cost estimates. Many of the projects included providing bid and construction assistance services after the design phase.

Atul’s professional expertise also includes preparation of ITS plans, traffic handling plans, traffic operational analysis, Safe Route to School studies, bicycle and pedestrian circulation studies and parking studies.

Lawrence Liao

Lawrence Liao

Director, Travel Demand Modeling

Mr. Liao has more than 16 years of experience in the areas of travel demand forecasting and software tool development. Lawrence has developed or updated travel demand models at various levels – from cities, counties, MPOs to states. He has also provided travel modeling support for various projects, such as traffic impact studies, general plan update, environmental impact reports/environmental impact statements, corridor studies, transit-oriented development, corridor system management plans, managed lane modeling, as well as federal research projects. In addition, Lawrence also developed customized software tools to post process microsimulation model output and facilitate data exchange across software platforms.

He is experienced in all major travel demand modeling software packages, including Cube, TransCAD, EMME, VISUM, Tranplan, and MinUTP, as well as, common programming languages, such as, Python, Java, MS Office VBA, C++, Pascal, and Fortran. Lawrence is one of only five certified Cube Trainers in the world and is a former technical support lead at Citilabs — the software vendor for Cube-Voyager package. He has provided Cube technical support, conducted numerous Cube model training, and is an expert in Cube-Voyager/TP+ scripting.