The Summer 2015 issue contains the usual wide variety of contemporary transportation topics that is the distinguishing characteristic of JTRF. Topics in this issue include the following:
- Sustainability in marine terminals
- Highway interchange lighting prioritization
- Severity of vehicle crashes at highway-rail grade crossings
- Effect of compressed work week on transportation network performance
- Traffic demand models for mid-size networks
- Severity of pedestrian crashes at highway-rail grade crossings
- Effects of increased shuttle train movements on rail pricing in the Northern Plains
In “Sustaining Sustainability in Marine Terminals: A Strategic Framework,” Neha Mittal and co-authors examine “green” initiatives of top-five global marine terminal operators using a core competency framework. The authors classify the initiatives as technology centric, process centric, and relationship centric and develop strategies to implement the initiatives. They found that technological initiatives are easy to adopt and yield quicker impacts in reducing emissions. On the other hand, process centric and relationship centric initiatives are more difficult to deploy and take longer to yield benefits, but are difficult for competitors to imitate.
Srinivas Pulugurtha and Ravishankar Narayanan compare their interchange lighting prioritization called the “Total Design Process” to traditional methods in “Weights from a Safety Perspective for Interchange Lighting Prioritization.” The authors gathered data from 80 interchanges along nine road segments in North Carolina in both rural and urban areas to identify new factors, and to compare results obtained from current and updated lighting priority index tools. The authors found that considering the number of nighttime crashes by severity, instead of night-to-day crash ratios, for prioritization of lighting system installation or maintenance, would reduce the bias toward interchanges with fewer crashes.
In “Analyzing Severity of Vehicle Crashes at Highway-Rail Grade Crossings: Multinomial Logit Modeling,” Wei Fan and co-authors use a nominal response multinomial logit model to identify important factors in injury severity differences of vehicle crashes. They also explore the impact of these factors on three severity levels of vehicle-related crashes at highway-rail grade crossings (HRGCs). The authors found that when rail equipment with high speed strikes a vehicle, the chance of a fatality increased. They also found that pickup trucks and concrete and rubber surfaces were more likely to be involved in more severe crashes. However, truck-trailer vehicles, snow and foggy weather, development area types (i.e., residential, commercial) and higher traffic volumes were more likely to be involved in less severe crashes.
Venkata Duddu and Srinivas Pulugurtha evaluate and assess the effect of a compressed work week strategy on transportation network performance in “Assessing the Effect of Compressed Work Week Strategy on Transportation Network Performance Measures.” The network performance measures include link-level traffic speed, travel time, and volume to capacity ratio using data from Charlotte, North Carolina. They found that reducing 15% to 20% of the traffic during the morning peak hours using a compressed work week would increase travel speeds by up to 5 mph on at least 64% of center-lane miles. They also found that a compressed work week would decrease the travel time by up to two minutes on at least 61% of center lane miles.
In “What Matters Most in Transportation Demand Model Specifications: A Comparison of Outputs in a Mid-size Network,” Donna Chen, Kara Kockelman, and Yong Zhao examine the impact of travel demand modeling (TDM) disaggregation techniques for mid-size communities. Specific TDM improvement strategies are evaluated for predictive power and flexibility with case studies based on the Tyler, Texas, network. The authors found that adding time of day disaggregation, particularly in conjunction with multiclass assignment to a basic TDM framework, has the most significant impacts on outputs. Other strategies that had an impact on outputs include adding a logit mode choice model and incorporating a congestion feedback loop.
Aemal Khattak and Li-Wei Tung quantify the impacts of various factors on three different severity levels of pedestrian injuries in crashes at highway-rail grade crossings in “Severity of Pedestrian Crashes at Highway-Rail Grade Crossings.” The authors employed an ordered probit model estimated with maximum likelihood with crash seventy as the dependent variable. The severity levels of pedestrian injuries were classified as no injury, injury, and fatality. The explanatory variables were grouped in five categories, including pedestrian characteristics, crash characteristics, crossing characteristics, train characteristics, and environment. The authors found that pedestrian fatalities were associated with higher train speeds and with female pedestrians. Crossings with more highway lanes and those with standard flashing light signals were associated with lower likelihood of pedestrian fatalities.
In “Hard Red Spring Wheat Marketing: Effects of Increased Shuttle Train Movements on Railroad Pricing in the Northern Great Plains,” Elvis Ndembe examines the impact of shuttle trains on hard red spring wheat transport from North Dakota. The author specified a model of railroad pricing estimated with OLS. The explanatory variables include the following:
- Length of haul
- Distance to a barge loading location
- Number of railcars in the shipment
- Weight per railcar
- Time trend
- Seasonal dummy variables
- Shuttle train shipment dummy variable
- Origin region dummy variables
With one exception, all the explanatory variables have the theoretically expected sign and are statistically significant. The author found that intermodal competition and shuttle trains played a significant role in rail rate reduction in North Dakota during the 1999-2012 period.