I am the Co-Director of the Transportation Technology and People Lab. TTP is a group of multidisciplinary faculty members, researchers, and students evaluating new technologies and applying avanced modeling and data analysis techniques. More details can be found in the TTP lab webpage.

My research focuses on enhancing system efficiency via the development of novel mathematical models based on application of large scale optimization, data mining, and system simulation tools. The primary innovation of my work is in the representation of network uncertainty, robustness, user behavior, and complex system interaction in civil infrastructure networks which together permit a long-term comprehensive analysis. A significant portion of my work deals with mitigating the impact of uncertainty in transportation models. Some of the research topics in which I am interested in working are listed below.

**Stochastic Network Infrastructure Systems Optimization:**Stochastic and Robust Network Infrastructure Modeling and Optimization, Resilience of Network Infrastructure, Algorithms for Reliable Design and Planning of Civil Infrastructure Systems under Uncertainty and Extreme Events**Network Assignment and Planning:**Network Assignment with Adaptive Routing and Information, Large Scale Dynamic Multi-modal Transportation Network Analysis, Modeling Traffic Network Performance under Autonomous Vehicles, Evaluating Intelligent Transportation Systems**Freight and Logistics:**Freight Network Optimization under Uncertainty, Collaborative Freight and Logistics, Sustainable Freight Planning and Green Logistics**Pedagogy:**Active Learning Techniques and Undergraduate Research for Promotion of Lifelong Learning and Innovation Capacity in Students

- M. Shahabi, A. Tafreshian, A. Unnikrishnan, and S.D. Boyles. Joint productionâ€“inventoryâ€“location problem with multi-variate normal demand.
*In Press: Transportation Research Part B: Methodological*, 2018. - T. Rambha, S.D. Boyles, A. Unnikrishnan, and P. Stone. Marginal cost pricing for system optimal traffic assignment with recourse under supply-side uncertainty.
*In Press: Transportation Research Part B: Methodological*, 2018. - P. Puntiya, A. Karoonsoontawong, A. Unnikrishnan, and C. Xie. Tabu Search Heuristic for Joint Location-Inventory Problem with Stochastic Inventory Capacity and Practicality Constraints.
*In Press: Networks and Spatial Economics*, 2017. - F. Nasr-Azadani, R. Khan, A. Unnikrishnan, A. Akanda, M. Alam, A. Huq, A. Jutla, and R. Colwell. Hydroclimatic sustainability assessment of changing climate on cholera in the Ganges-Brahmaputra Basin.
*Advances in Water Resources*, Volume 89, 332-344, 2017. - Z. Zhang and A. Unnikrishnan. A coordinated location-inventory problem in closed-loop supply chain.
*Transportation Research Part B: Methodological*, Volume 89, 127- 148, 2016. - A. Kar, I. Ray, U.B. Halabe, and A. Unnikrishnan. Physicochemical and microstructural characterizations of alkali-activated binder systems.
*International Journal of Structural and Civil Engineering Research*, Volume 5, Issue 2, 2016. - A. Kar, U.B. Halabe, I. Ray, and A. Unnikrishnan. Comparison of linear regression models for properties of alkali activated binder concrete.
*European Scientific Journal*, Volume 11, Issue 27, 2015. - A. Jutla, A. Akanda, A. Unnikrishnan, A. Huq, and R. Colwell. Predictive time series analysis linking bengal cholera with terrestrial water storage measured from gravity recovery and climate experiment sensors.
*The American Journal of Tropical Medicine and Hygiene*, Volume 93, Issue 6, 1179-1186, 2015. - F. Nasr-Azadani, A. Unnikrishnan, A. Akanda, S. Islam, M. Alam, A. Huq, A. Jutla, and R. Colwell. A framework for downscaling river discharge to assess the effects of climate change on endemic cholera.
*Climate Research*, Volume 64, Issue 3, 257-274, 2015. - S. Agrawal, N. Jiang, S. Boyles, M. Shahabi, and A. Unnikrishnan. A network route choice model for bev drivers with different risk attitudes.
*Transportation Research Record: Journal of the Transportation Research Board*, Volume 2498, 75-83, 2015. - J. Pahukula, S. Hernandez, and A. Unnikrishnan. A time of day analysis of crashes involving large trucks in urban areas.
*Accident Analysis and Prevention*, Volume 75, 155- 163, 2015. - S. Boyles, S. Tang, and A. Unnikrishnan. Parking search equilibrium on a network.
*Transportation Research Part B: Methodological*, Volume 81, 390-409, 2015. - M. Shahabi, A. Unnikrishnan, and S. Boyles. Robust optimization strategy for the shortest path problem under uncertain link travel cost distribution.
*Computer Aided Civil and Infrastructure Engineering*, Volume 30, Issue 6, 433-448, 2015. - M. Shahabi and A. Unnikrishnan. Robust hub network design problem.
*Transportation Research Part E: Logistics and Transportation Review*, Volume 70, 356-374, 2014. - M. Shahabi, A. Unnikrishnan, E.J. Shirazi, and S. Boyles. A three level location-inventory problem with correlated demand.
*Transportation Research Part B: Methodological*, Volume 69, 1-18, 2014. - J.C. Duthie and A. Unnikrishnan. An optimization framework for bicycle network design.
*ASCE Journal of Transportation Engineering*, Volume 40, Issue 7, 2014. - H. Wang, A. Unnikrishnan, S. Hernandez, and R.L. Cheu. A capacitated centralized carrier collaboration multihub location problem: a tabu search approach.
*Transportation Research Record: Journal of Transportation Research Board*, Volume 2466, 22-30, 2014. - S. Tang, T. Rambha, R. Hatridge, S. Boyles, and A. Unnikrishnan. Modeling parking search on a network using stochastic shortest paths with history dependence.
*Transportation Research Record: Journal of Transportation Research Board*, Volume 2467, 73-79, 2014. - A. Kar, I. Ray, U. B. Halabe, A. Unnikrishnan, and B. Dawson-Andoh. Characterizations and quantitative estimation of alkali-activated binder paste from microstructures.
*International Journal of Concrete Structures and Materials*, Volume 8, No. 3, 213-228, 2014. - M. Shahabi, A. Unnikrishnan, and S. Boyles. An outer approximation algorithm for the robust shortest path problem.
*Transportation Research Part E: Logistics and Transportation Review*, Volume 58, 52â€“66, 2013. - M. Shahabi, S. Akbarinasaji, A. Unnikrishnan, and R. James. Integrated inventory control and facility location decisions in a multi-echelon supply chain network with hubs.
*Networks and Spatial Economics*, Volume 13, Issue 4, 497-514, 2013. - R. James, A. Unnikrishnan, and R. Sharma. Statistical regression models for predicting swelling pressure of compacted expansive soils.
*International Journal of Geotechnical Engineering*, Volume 7, Issue 4, 431-438, 2013. - A. Karoonsoontawong and A. Unnikrishnan. Tabu search heuristics for inventory routing problem with route duration limits and stochastic inventory capacity constraints.
*Transportation Research Record: Journal of Transportation Research Board*, Volume 2378, 43-53, 2013. - A. Kar, U.B. Halabe, I. Ray, and A. Unnikrishnan. Nondestructive characterizations of alkali activated fly ash and/or slag concrete.
*European Scientific Journal*, Volume 9, Issue 4, 52-74, 2013. - A. Kar, I. Ray, A. Unnikrishnan, and J. F. Davalos. Composite modeling to predict shrinkage of concrete containing supplementary cementitious materials from paste volumes.
*Construction and Building Materials*, Volume 43, 139- 155, 2013. - A. Unnikrishnan and D.Y. Lin. User equilibrium with recourse: network design problem.
*Computer Aided Civil and Infrastructure Engineering*, Volume 27, Issue 7, 512-524, 2012. - A. Unnikrishnan, M. Shahabi, and M. Figliozzi. Integer multicommodity flow with recourse model for network assignment problem of capacitated freight with disruptions.
*Transportation Research Record: Journal of Transportation Research Board*, Volume 2269, 11-19, 2012. - S. Hernandez, A. Unnikrishnan, and S.S. Awale. A less-than-truckload centralized carrier collaboration multi-hub location problem: A hybrid hub-and-spoke network.
*Transportation Research Record: Journal of Transportation Research Board*, Volume 2269, 20-28, 2012. - R. Kumar, A. Unnikrishnan, and S.T. Waller. a heuristic scheme for the heterogeneous vehicle routing problem on trees based on generalized assignment and bin-packing upper bounds.
*Transportation Research Record: Journal of Transportation Research Board*, Volume 2283, 1-11, 2012. - E. Ferguson, J.C. Duthie, A. Unnikrishnan, and S.T. Waller. Incorporating environmental justice into the transit frequency-setting problem.
*Transportation Research Part A: Policy and Practice*, Volume 46, Issue 1, 190 -199, 2012. - A. Kar, I. Ray, A. Unnikrishnan, and J.F. Davalos. Estimation of C-S-H and calcium hydroxide for cement pastes containing slag and silica fume.
*Construction and Building Materials*, Volume 30, 505-515, 2012. - A. Kar, I. Ray, A. Unnikrishnan, and J.F. Davalos. Microanalysis and optimization based C-S-H estimation of cementitious systems containing fly ash and silica fume.
*Cement and Concrete Composites*, Volume 43, Issue 3, 419-429, 2012. - E. Bailey, A. Unnikrishnan, and D.Y. Lin. Models for minimizing backhaul costs through freight collaboration.
*Transportation Research Record: Journal of Transportation Research Board*, Volume 2224, 51-60, 2011. - A. Unnikrishnan and M. Figliozzi. An online freight network assignment model with transportation disruptions and recourse.
*Transportation Research Record: Journal of Transportation Research Board*, Volume 2224, 17-25, 2011. - R. Kumar, A. Unnikrishnan and S.T. Waller. The capacitated vehicle routing problem with backhauls on trees: model, properties, formulations, and algorithm.
*Transportation Research Record: Journal of Transportation Research Board*, Volume 2263, 92-102, 2011. - A. Voruganti, A. Unnikrishnan and S.T. Waller. Modeling collaboration in freight networks.
*Transportation Letters*, Volume 3, Issue 1, 51-61, 2011.

- J.D. Lemp, K.M. Kockelman, and A. Unnikrishnan. Analysis of large truck crash severity using heteroskedastic ordered probit models.
*Accident Analysis and Prevention*, Volume 43, 370-380, 2011. - D.Y. Lin, A. Unnikrishnan, and S.T. Waller. A dual variable approximation based heuristic for dynamic congestion pricing.
*Networks and Spatial Economics*, Volume 11, Issue 2, 271-193, 2011. - J.C. Duthie, A. Unnikrishnan, and S.T. Waller. Influence of demand uncertainty and correlations on traffic predictions and decisions.
*Computer Aided Civil and Infrastructure Engineering*, Volume 26, Issue 1, 16-29, 2011. - L.M. Gardner, A. Unnikrishnan, and S.T. Waller. Solution methods for robust pricing of transportation networks under uncertain demand.
*Transportation Research Part C: Emerging Technologies*, Volume 18, Issue 5, 656-667, 2010. - A. Unnikrishnan and S.T. Waller. User equilibrium with recourse.
*Networks and Spatial Economics*, Volume 9, Issue 4, 575-593, 2009. - A. Unnikrishnan, V. Valsaraj, and S.T. Waller. Stochastic and dynamic shipper carrier network design problem.
*Networks and Spatial Economics*, Volume 9, Issue 4, 525-550, 2009. - D.Y. Lin, A. Unnikrishnan, and S.T. Waller. A genetic algorithm for bi-level linear programming dynamic network design problem.
*Transportation Letters*, Volume 1, Issue 4, 281-294, 2009. - A. Unnikrishnan, and S.T. Waller. Freight transportation network design problem for maximizing throughput under uncertainty.
*Transportation Research Record: Journal of the Transportation Research Board*, Volume 2090, 105-114, 2009. - A. Unnikrishnan, V. Valsaraj, I. Damnjanovic, and S.T. Waller. Design and management strategies for mixed public private transportation networks: A meta-heuristic approach.
*Computer Aided Civil and Infrastructure Engineering*, Volume 24, Issue 4, 266-279, 2009. - L.M. Gardner, A. Unnikrishnan and S.T. Waller. Robust pricing for transportation networks with demand uncertainty.
*Transportation Research Record: Journal of Transportation Research Board*, Volume 2085, 21-30, 2008. - N.R. Juri, A. Unnikrishnan, and S.T. Waller. Integrated traffic simulation-statistical analysis framework for online prediction of freeway travel time.
*Transportation Research Record: Journal of the Transportation Research Board*, Volume 2039, 24-31, 2007.

- R. Sharma, and A. Unnikrishnan. Evaluation of student perception of civil and environmental engineering undergraduate research.
*Proceedings of the 97th Annual Meeting of the Transportation Research Board*, Washington, D.C, 2018. - P. Puntiya, A. Karoonsoontawong, A. Unnikrishnan, and C. Xie. Tabu Search Heuristic for Joint Location-Inventory Problem with Stochastic Inventory Capacity and Practicality Constraints.
*Proceedings of the 97th Annual Meeting of the Transportation Research Board*, Washington, D.C, 2018. - M. Shahabi, A. Tafreshian, A. Unnikrishnan, and S. Boyles. Joint production-inventory-location problem with correlated demand.
*Proceedings of the 95th Annual Meeting of the Transportation Research Board*, Washington, D.C, 2016. - J. Elyard, A. Unnikrishnan, D. Martinelli, A. Nichols, C. Frosch, R. James, and M. Shahabi. Evaluation of public perception and outreach efforts for roundabouts in Fairmont, West Virginia.
*Proceedings of the 95th Annual Meeting of the Transportation Research Board*, Washington, D.C, 2016. - S. Boyles, S. Tang, and A. Unnikrishnan. Parking search equilibrium on a network.
*Proceedings of the 94th Annual Meeting of the Transportation Research Board*, Washington, D.C, 2015. - S. K. Agrawal, S. Boyles, N. Jiang, M. Shahabi, and A. Unnikrishnan. A network route choice model for battery electric vehicles with different risk attitudes.
*Proceedings of the 94th Annual Meeting of the Transportation Research Board*, Washington, D.C, 2015. - J. Pahukula, S. Hernandez, and A. Unnikrishnan. A time of day analysis of crashes involving large trucks in urban areas.
*Proceedings of the 94th Annual Meeting of the Transportation Research Board*, Washington, D.C, 2015. - S. Boyles, S. Tang, and A. Unnikrishnan. Dynamic traffic assignment and the parking search process.
*Fifth International Symposium on Dynamic Traffic Assignment*, Salerno, Italy, 2014. - H. Wang, A. Unnikrishnan, S. Hernandez, and R.L. Cheu. A capacitated centralized carrier collaboration multihub location problem: A tabu search approach.
*Proceedings of the 93rd Annual Meeting of the Transportation Research Board*, Washington, D.C, 2014. - M. Shahabi, A. Unnikrishnan, and S. Boyles. A new algorithm for the non-additive shortest path problem.
*Proceedings of the 93rd Annual Meeting of the Transportation Research Board*, Washington, D.C, 2014. - S. Tang, T. Rambha, R. Hatridge, S. Boyles, and A. Unnikrishnan. Modeling parking search on a network using stochastic shortest paths with history dependence.
*Proceedings of the 93rd Annual Meeting of the Transportation Research Board*, Washington, D.C, 2014. - R. Venkatraman, S. Boyles, R. James, and A. Unnikrishnan. Adaptive routing behavior with real time information under multiple travel objectives.
*Proceedings of the 93rd Annual Meeting of the Transportation Research Board*, Washington, D.C, 2014. - A. Karoonsoontawong and A. Unnikrishnan. Tabu search heuristics for inventory routing problem with route duration limits and stochastic inventory capacity constraints.
*Proceedings of the 92ndt Annual Meeting of the Transportation Research Board*, Washington, D.C, 2013. - A. Kar, I. Ray, A. Unnikrishnan, J.F. Davalos, and A. Chen. Prediction of shrinkage of concrete containing fly ash and/or silica fume using composite modeling.
*Proceedings of ASCE Conference on Earth and Space 2012: Engineering, Science, Constructions, and Operations in Challenging Environments*, California, 732- 743, 2012. - A. Unnikrishnan, M. Shahabi, and M. Figliozzi. A model and heuristic solution approach for the capacitated freight on-line network assignment with transportation disruptions and recourse.
*Proceedings of the 91st Annual Meeting of the Transportation Research Board*, Washington, D.C, 2012. - S. Hernandez, A. Unnikrishnan, and S.S. Awale. A less-than-truckload centralized carrier collaboration multi-hub location problem: a hybrid hub-and-spoke network.
*Proceedings of the 91st Annual Meeting of the Transportation Research Board*, Washington, D.C, 2012. - R. Kumar, A. Unnikrishnan, and S.T. Waller. A heuristic scheme for the heterogeneous vehicle routing problem on trees based on generalized assignment and bin-packing upper bounds.
*Proceedings of the 91st Annual Meeting of the Transportation Research Board*, Washington, D.C, 2012. - E. Bailey, A. Unnikrishnan, and D.Y. Lin. Capacitated loop problem and allocation mechanism for shipper collaboration.
*Proceedings of the 91st Annual Meeting of the Transportation Research Board*, Washington, D.C, 2012. - A. Unnikrishnan and D.Y. Lin. Probit based stochastic user equilibrium with recourse: Network design problem.
*Proceedings of the 90th Annual Meeting of the Transportation Research Board*, Washington, D.C, 2011. - E. Bailey, A. Unnikrishnan, and D.Y. Lin. Models for minimizing backhaul costs through freight collaboration.
*Proceedings of the 90th Annual meeting of the Transportation Research Board*, Washington, D.C, 2011. - A. Unnikrishnan and M. Figliozzi. An online freight network assignment model with transportation disruptions and recourse.
*Proceedings of the 90th Annual Meeting of the Transportation Research Board*, Washington, D.C, 2011. - R. Kumar, A. Unnikrishnan, and S.T. Waller. The capacitated vehicle routing problem with backhauls on trees: model, properties, formulations, and algorithm.
*Proceedings of the 90th Annual Meeting of the Transportation Research Board*, Washington, D.C, 2011. - J.D. Lemp, K.M. Kockelman, and A. Unnikrishnan. Analysis of large truck crash severity using heteroskedastic ordered probit models.
*Proceedings of the 90th Annual Meeting of the Transportation Research Board*, Washington, D.C, 2011. - M. Thompson, A. Unnikrishnan, A. Conway, and C.M. Walton. Reducing heavy truck emissions: A survey of regulations and policies.
*Proceedings of the 89th Annual Meeting of the Transportation Research Board*, Washington, D.C, 2010. - A. Nimbarte, A. Unnikrishnan, and F. Aghazadeh. Loading of Cervical Spine during isometric overhead exertions.
*Proceedings of the Industrial Engineering Research Conference*, Cancun, 2010. - A. Unnikrishnan and S.T. Waller. Freight transportation network design problem for maximizing throughput under demand uncertainty.
*Proceedings of the 88th Annual Meeting of the Transportation Research Board*, Washington, D.C, 2009. - D.Y. Lin, A. Unnikrishnan, and S.T. Waller. A two-stage decomposition heuristic for dynamic congestion pricing.
*Proceedings of DTA 2008, International Symposium on Dynamic Traffic Assignment*, Leuven, Belgium. - L.M. Gardner, A. Unnikrishnan, and S.T. Waller. Computational methods to arrive at robust prices in transportation networks with demand uncertainty.
*Proceedings of the 10th International Conference on Applications of Advanced Technologies in Transportation*, Greece, 2008. - L.M. Gardner, A. Unnikrishnan and S.T. Waller. Robust pricing for transportation networks with demand uncertainty.
*Proceedings of the 87th Annual Meeting of the Transportation Research Board*, Washington, D.C, 2008. - A. Unnikrishnan, V. Valsaraj, I. Damnjanovic, and S.T. Waller. Modeling private public partnership in maintenance, rehabilitation and construction of roadway infrastructure systems.
*Proceedings of the 87th Annual Meeting of the Transportation Research Board*, Washington, D.C, 2008. - N. R. Juri, A. Unnikrishnan, and S.T. Waller. Integrated traffic simulation-statistical analysis framework for the online prediction of freeway travel time.
*Proceedings of the 86th Annual Meeting of the Transportation Research Board*, Washington, D.C, 2007. - J. C. Duthie, A. Unnikrishnan, and S. T. Waller. Network evaluation with uncertain and correlated long term demands.
*Proceedings of the 85th Annual Meeting of the Transportation Research Board*, Washington, D.C, 2006. - A. Unnikrishnan, S. Ukkusuri and S. T. Waller. Sampling techniques for evaluating the traffic equilibrium problem under uncertain demand.
*Proceedings of the 84th Annual Meeting of the Transportation Research Board*, Washington, D.C, 2005.