TRB 2016 Blue Ribbon Committee
16th National Transportation Planning Applications Conference


Corresponding Author: Jon Markt, HDR Engineering

Presented By: Jon Markt, HDR Engineering, Inc.


Technology is changing the world around us, including transportation. What does a future interstate look like in the face of these changes? Road trains of self-driving cars? Driverless freight trucks? Virtually incident-free travel? Travel lanes as narrow as 8’? Iowa DOT has plans to widen Interstate 80 statewide and before committing Iowans to paying for a 4-lane to 8-lane freeway expansion, the DOT partnered with HDR and Iowa State University to determine how future technologies could impact interstate operations.

The study team developed an approach to right-size and future-proof Interstate 80 to promote adaptable design to the uncertain future the corridor faces. Step one of the study approach is to strategically identify future scenarios to set key technology adoption assumptions at the outset of traffic and safety analysis. Technology will be evaluated both in terms of how transportation supply and demand might be affected by technology. Demand forecasts from the Iowa DOT statewide model will be adjusted to include evolving trends as diverse as generational decreases in auto ownership, the impact of e-commerce, and latent demand of autonomous vehicle owners previously unable to drive a vehicle.

Step two is to synthesize existing research on technology impacts to safety and traffic flow. In the analysis of traffic flow, future scenarios will be evaluated to determine traffic quality of service and reliability using a combination of analytical and simulation procedures. Microsimulation of classes of both human-operated and automated vehicles will be conducted to validate past research on automated vehicle impacts under the unique conditions of rural interstate travel. Interstate safety evaluations will be conducted using methods from the AASHTO Highway Safety Manual and Crash Modification Factors synthesized from existing research. The traffic capacity and safety analysis results will feed reliability analysis using methods from SHRP2 research to identify technology benefits to traffic operations beyond those postulated from traffic capacity analysis alone.

The final step of the study will be to synthesize freeway capacity and speed as a function of technology market penetration, allowing DOT to keep the findings of this study as flexible as the rapidly changing technology market.


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