The Spring 2016 issue contains the usual wide variety of contemporary transportation topics that is the distinguishing characteristic of JTRF. Topics in this issue include the following:

• Highway bridge component deterioration
• Driving knowledge and motor vehicle fatalities
• Airline fuel hedging
• Crop supply chain and transportation emissions
• Modified transportation systems and home location
• Multimodal connectivity of BRT stations
• Illumination of Overhead Guide Signs

In “Regression Model Evaluation for Highway Bridge Component Deterioration Using National Bridge Inventory Data,” Pan Lu and co-authors develop an external validation procedure to quantitatively compare the forecasting power of different regression models for highway bridge component deterioration. They compared several regression models using the proposed procedure and traditional apparent model based on goodness of fit. The procedure developed by the authors has four steps, which are (1) select prediction analysis period, (2) data is segregated into two parts, one containing the latest data within the analysis period and the rest of the data used to develop regression parameters, (3) the predictive model is used to predict the data in the desired time horizon compared to the true data, which are the set-aside data and (4) the forecasting skill trend over time is analyzed.

Walter Simmons, Andrew Welki, and Thomas Zlatoper analyze the effect of driving knowledge on highway safety in “The Impact of Driving Knowledge on Motor Vehicle Fatalities.” The authors estimate regression models on state-level data over the 2005-2010 period. The models contain a representative set of motor vehicle fatality determinants including driving knowledge. Driving knowledge is measured by performance on the GMAC Insurance National Drivers Test. The authors found that real per-capita income, precipitation, seat belt use, and a linear trend were negatively related to the motor vehicle death rate and are statistically significant. Also, the ratio of rural to urban driving, temperature, the percentage of young drivers, the percentage of old drivers, and alcohol consumption were positively related to the death rate and statistically significant. The authors found that the performance on the GMAC test has a statistically significant life-saving effect.

In “Airline Fuel Hedging: Do Hedge Horizon and Contract Maturity Matter,” Siew Hoon Lim and Peter Turner examined weather the length of hedge horizon and distance to contract maturity affect the effectiveness of jet fuel cross hedging (some underlying asset highly correlated to jet fuel price). To answer the question in the title the authors examine the hedging performance of four common jet fuel proxies: West Texas Intermediate (WTI) crude oil, Brent crude oil (Brent), heating oil, and gasoil. The authors found that regardless of the distance to contract maturity, weekly hedge horizon has the best effectiveness for jet fuel proxies like heating oil, Brent, WTI, and gasoil. They found that heating oil is the best jet fuel proxy for all hedge horizons and contract maturities. Also the hedge effectiveness of heating oil is higher for one-month and three-month contracts.

T. Edward Yu and co-authors conduct a study that minimizes total cost for single feedstock supply chains for two dedicated energy crops in “Dedicated Crops Supply Chains and Associated Feedstock Transportation Emissions: A Case Study of Tennessee.” The dedicated energy crops are perennial switchgrass and biomass sorghum. Using a spatial optimization model of greenhouse gas emissions from the transport of feedstock to the conversion facility were estimated for the respective feedstock supply chains. The authors found that different demand for land types of the two feedstocks and the geographically diverse landscape across the state affect the economics of bioenergy crop supply chains and feedstock transportation emissions. The authors concluded that switchgrass is more suitable than biomass sorghum for biofuel production in Tennessee based on the supply chains cost and feedstock hauling emissions.

In “Welfare Measures to Reflect Home Location Options When Transportation Systems Are Modified,” Shuhong Ma and Kara Kockelman examine the welfare (willingness to pay impacts) of transportation system changes. The authors do this by bringing residential location choice into a three-layer nested logit model to anticipate regional welfare impacts of transportation system shifts using consumer surplus. The model is applied to a sample of 60 Austin, Texas zones to estimate home buyers’ welfare impacts across various scenarios with different transit fares, auto operating costs, travel times, and home prices. The results suggest that new locators’ choice probabilities for rural and suburban zones are more sensitive to changing regional access, while urban and central business zone choice probabilities are more impacted by home price shifts. Also they noted that auto costs play a more important role in residential location choices in these simulations than those of transit.

Mintesnot Woldeamanuel and Craig Olwert develop a multimodality Index (MI) to evaluate the accessibility and convenience of transit use in “The Multimodal Connectivity at Bus Rapid Transit (BRT) Stations and the Impact on Ridership.” They point out that the integration of the Orange Line BRT system in Los Angeles with other travel modes, including bicycles, regular buses, and cars, was analyzed using field observations and LA Metro data to create an MI. The major objective is to determine if ridership is higher at stations with better multimodal connectivity. The authors found that multimodal connectivity varies across stations on the Orange Line BRT system. However, a positive relationship exists between ridership and the MI, indicating that MI is a reliable predictor of transit ridership and a useful tool for transit planning.

In “Effective Light Source for Illuminating Overhead Guide Signs and Improving Roadway Safety,” Mohammed Obeidat and Malgorzata Rys compare the illumination of five alternate light sources. The authors analyze the illumination of High Pressure Sodium (HPS), Metal Halide (MH), Mercury Vapor (MV), induction lighting and Light Emitting Diode (LED). The authors conducted a laboratory experiment to compare the light distribution of each light source. Also, a cost analysis was performed to compare initial, maintenance, and operating cost components of the light sources. The authors found that HPS was the optimum light source, and induction lighting was the least cost source of the five light sources and provided the best overall performance when considering initial costs, operating cost, expected maintenance, and sign illuminance.