Jeffrey Shelton

Applying Dynamic Modeling Methods to IH 35 Through Austin: Exploring Options for Addressing Future Congestion

ABSTRACT The City of Austin is among the fastest-growing cities in the U.S., with the surrounding counties keeping a similar pace. Travel times from downtown Austin to Round Rock, where many commuters live, currently range from 45 to 60 minutes during the average afternoon rush hour. Decision-makers have expressed a need to examine long-term solutions for IH 35 to explore concepts discussed under previous studies. This study applied dynamic traffic assignment coupled with static and dynamic tolling analysis, user class restrictions and multi-class simulation and assignment to examine various long-term scenarios with potential to address growing congestion on this critical corridor. The findings were illuminating: if residential and employment growth continue on their current pace through 2035, the region wide dynamic traffic assignment results applied at the mesoscopic level in this study demonstrate that Central Texas faces a grim future of extreme traffic congestion on IH 35. While an added capacity scenario was identified which can address future IH 35 congestion in some instances, it is of questionable viability for implementation. The scenario with the largest capacity addition did not provide the best results due to limited accessibility and only when the limits were extended dramatically, did researchers find more positive congestion relief. However, this scenario would be the highest investment and would probably be deemed infeasible simply due to cost. A more positive finding was that a hybrid strategy of added capacity, dynamic tolling, and travel demand management solutions demonstrates even greater benefits. When all options were considered, it was realized that added capacity would not be enough; it would need to be coupled with managed lanes, changes in travel behavior, more efficient land use, demand management and increased transit use.

Methodology for Microscopic Traffic Simulation Modelling of Land Port of Entries along the U.S.-Mexican Border: Ysleta – Zaragoza Land Port of Entry Case Study

Land Ports of Entry (LPOEs) are facilities that control access into the U.S., as well as departures of persons and freight. While traffic simulation modeling techniques are not typically used to evaluate LPOE operational processes, they should be considered more often, because LPOEs have a significant impact on surrounding traffic conditions and vice versa. This paper proposes a methodology for developing microscopic traffic simulation models of LPOEs along the U.S.-Mexico border. The methodology consists of seven steps: (i) collect data; (ii) develop traffic or roadway network; (iii) model inspection and toll booths; (iv) develop traffic management strategies; (v) set up traffic demand; (vi) calibrate model; and (vii) validate model. The paper also presents a case study in which this methodology was followed to develop the Ysleta – Zaragoza LPOE traffic simulation model, which can be controlled from a web-based interface to help LPOE personnel without previous transportation modeling experience.

Multiresolution visualization tools to aid in conducting road safety audits

Typical road safety audits use site investigations in addition to historical data to make recommendations. Recent approaches have used simulation modeling to derive surrogate measures to analyze the potential for collisions, driving simulators to analyze human behavior, or other visualization tools to analyze geometric design characteristics. None of these tools can capture the dynamics of proposed changes that subsequently alter traffic patterns. Each proposed improvement has an influence on traffic patterns and must be captured at a regional level to determine whether vehicles choose the same path or defer to an alternative one. This study explored new methods to supplement the Road Safety Audit process. The study used visualization tools to assess the performance of each proposed improvement strategy by conducting a more thorough comprehensive safety study with multiresolution modeling methods in situations when suggested countermeasures would almost certainly redistribute traffic to alternative routes. A case study was selected in which an audit team performed a safety audit of a diamond interchange in El Paso, Texas, that experienced a high number of collisions during peak hours. The visualization of the proposed improvement scenarios helped the Texas Department of Transportation understand better how mitigation strategies would influence traffic flow in and around the study area or whether the proposed changes improved safety or merely shifted the problem to alternative locations. The use of visualization tools can help convey proposed improvements to the public.

Regional Impact of Roadway Construction on Traffic Operations

The objective of this study was to develop a methodology for assessing the impact of road construction that could be used to (a) predict the network-level impact of road construction projects, (b) identify critical roadway segments and corridors in which the impacts of construction are expected to be the most severe, and (c) compare alternative construction scenarios and schedules. Dynamic traffic assignment formed the basis of an approach to assess the regional impact of road construction and compare alternative construction schedule scenarios. The application of the model was illustrated with the use of a hypothetical case of two road construction projects in the roadway system of El Paso, Texas.