TRB Showcase of Portland State University student research in transportation: Part 1

Friday, January 13, 2012, 12:00pm to 1:00pm PST
Wei Feng, Sirisha Kothuri, Brian Davis (PSU)

The video begins at 4:13.

Wei Feng: Impacts of Economic, Technological and Operational Factors on the Economic Competitiveness of Electric Commercial Vehicles in Fleet Replacement Decisions

Electric commercial vehicles (ECV) have the potential to substantially reduce greenhouse gas emissions, noise, and pollution in urban areas. In addition, ECVs have lower per-mile operating costs and potentially lower maintenance costs. However, the initial purchase cost of ECVs is significantly higher than the purchase cost of a conventional diesel vehicle. From a purely economic perspective, there is a cost tradeoff between the low operating and maintenance costs of ECVs and their high initial capital costs.  In this paper, a fleet replacement optimization framework is employed to analyze the competitiveness of ECVs. Scenarios with different fleet utilization, fuel efficiency and sensitivity analysis of ten additional factors indicate that ECVs are more cost effective when conventional diesel vehicles’ fuel efficiency is low (8.2 miles/gallon) and daily utilization is more than 54 miles. Breakeven values of some key economic and technological factors that separate the competitiveness between ECVs and conventional diesel vehicles are calculated in all scenarios. For example, in low conventional diesel vehicle fuel efficiency and low daily utilization scenario, ECVs are more competitive when their purchase prices are less than $135,586.

Sirisha Kothuri: Preliminary Development of Methods to Automatically Gather Bicycle Counts and Pedestrian Delay at Signalized Intersections

The increase of bicycle and pedestrian traffic in many urban areas has led to growing interest in multimodal performance measures.  Traditionally, counts of pedestrians and bicycles have only been collected for short durations at spot locations.  The lack of reliable long-term data precludes systematic performance monitoring and analysis of trends. This paper summarizes preliminary efforts to develop a long-term monitoring and collection system that leverages existing infrastructure to monitor bicycle and pedestrian activity. Communication and logic protocols have been implemented to gather bicycle counts and pedestrian delay using existing hardware (loop detectors, signal controllers) and software at select intersections within the City of Portland, Oregon. Bicycle counts are being gathered using advance loops in bike lanes. Two novel methods for collecting pedestrian delay at signalized intersections are proposed in this paper. One method uses transit priority logging feature in the signal controller software to track individual pedestrian phase actuations and corresponding delay. The other method uses internal logic commands to capture pedestrian delay estimates in relevant bins. Both methods provide delay and number of pedestrian actuations which can be used to characterize the pedestrian LOS at an intersection. The results from the study reveal that automation of data collection techniques for generating multimodal performance measures can assist in analyzing performance and long-term trends. The methods developed in this study can benefit other regions in understanding the effects of signal timing settings on multimodal performance.

Brian Davis: The Competitiveness of Commercial Electric Vehicles in the LTL Delivery Industry: A Model and Application

A detailed model is developed to calculate logistics performance, energy use, and costs of electric vehicles and comparable diesel internal-combustion engine vehicles. This effort is a novel study of commercial electric vehicles because the implications of routing constraints, route parameters, and electric truck characteristics are analyzed integrating three models: (a) a vehicle ownership cost minimization model, (b) a model to calculate the power consumption and maximum potential range of an electric or conventional truck as a function of average velocity and weight, and (c) a continuous approximation model to estimate fleet size, distance traveled, and ensure that practical routing constraints are satisfied. The model is applied to the study the competitiveness of three vehicles of similar weight and size in the US market:  a widely available conventional diesel truck and two electric trucks. Scenarios and breakeven points are calculated and analyzed for a large number of parameter combinations.  In order for electric trucks to be competitive, the savings in energy costs over the lifetime of the truck must be great enough to counteract the much higher initial purchase cost.  The results provide new insights regarding the truck characteristics and logistical constraints that determine whether a conventional or electrical truck is more cost effective.