Highway Capacity Manual改訂の動向--テイラ-教授の講演より

The relationship between truck accidents and geometric design of road sections: Poisson versus negative binomial regressions.

A. Federal Highway Administration

The major contributor to global warming is human-generated greenhouse gases (GHGs) emissions that pollute the air. GHGs emissions are a global issue dominated by emission of carbon dioxide (CO2). Notably, CO2 accounts for an estimated 77% of GHGs and thus has a huge impact on the environment. The capture, sequestration, and utilization of CO2 emissions from flue gas are now becoming familiar worldwide. These methods are a promising solution to promote sustainability for the benefit of future generations. Previously, many researchers have focused on capturing and storing CO2; however, less effort has been spent on finding ways to utilize flue gas emissions. Moreover, several issues must be overcome in the field of carbon capture and sequestration (CCS) technology, especially regarding the cost, capacity of storage and the durability of the storage reservoir. In addition, this paper addresses new technology in carbon capture and sequestration. To make CCS technology more feasible, this paper suggests a sustainable method combining CCS and biofuel production using CO2 as a feedstock. This method offers many advantages, such as CO2 emission mitigation and energy security through the production of renewable energy. Due to the many advantages of biofuels, the conversion of CO2 into biofuel is a best practice and may provide a solution to pollution while encouraging sustainability practises.

Pollution to solution: Capture and sequestration of carbon dioxide (CO2) and its utilization as a renewable energy source for a sustainable future

Stakeholder management for public private partnerships

Work zone capacity values for rural and urban freeways without continuous frontage roads were defined and determined. Data were collected using Nu-Metrics counters and classifiers at 24 work zones in North Carolina. The research included analysis of speed-flow behavior, evaluation of work zone sites based on lane configuration and site location, and determination of the location within the work zone where capacity is lowest. It was shown that the intensity of work activity and the type of study site (rural or urban) strongly affected work zone capacity. The data suggested that the location where capacity is reached is also variable based on the intensity of work. For heavy work in a two-lane to one-lane work zone configuration, the capacity values proposed at the active work area are approximately 1,200 vehicles per hour per lane for rural sites and 1,500 vehicles per hour per lane for urban sites. It is recommended that two distinct volumes be used when queue behavior in a freeway work zone is analyzed. The collapse from uninterrupted flow (designated work zone capacity) and the lower queue-discharge volume both should be considered.

Capacity for North Carolina Freeway Work Zones

This two-part feature presents unconventional alternatives for arterials that, under certain circumstances, move traffic more efficiently than conventional arterials with fewer negative impacts than widening, bypasses or interchanges. The second part discusses paired intersections, which use directional crossovers for high through-traffic volumes and low cross-street through-traffic volumes; the jughandle alternative, which uses ramps diverging from the right side of the arterial to accommodate all turns from the arterial; the continuous flow intersection, which features a ramp to the left of the arterial upstream of the main intersection to handle traffic turning left from the arterial; and the continuous green T, which works only for three-approach intersections. Descriptions, variations, history, advantages and disadvantages are highlighted for each of the four alternatives. Traffic volume and necessary extra right of way for each alternative should also be considered.

http://onlinepubs.trb.org/onlinepubs/circulars/ec019/Ec019_e3.pdf

Unconventional left-turn alternatives for urban and suburban arterials--part one

The purpose of this study was to determine the effect on accidents of lane widening, shoulder widening, and shoulder surfacing. Detailed traffic, accident, roadway, and roadside data were collected on 4,951 miles of two-lane roadway in seven states. Statistical testing was used along with an accident prediction model to detemine the expected accident reductions related to various geometric improvements. Accident types found to be most related to cross-section features included run-off-road, head-on, and sideswipe (same direction and opposite direction) accidents. The roadway variables found to be associated with a reduced incidence of these related accident types (and included in the predictive model) are wider lanes, wider shoulders (paved slightly safer than unpaved), better roadside condition, flatter terrain, and lower traffic volume. Lane widening was shown to reduce related accidents by 12 percent for 1 foot of widening (for example, 10-foot lanes to 11-foot lanes), 23 percent for 2 feet of widening, 32 percent for 3 feet of widening, and 40 percent for 4 feet of widening. The effects of shoulder widening on related accidents was determined for paved and unpaved shoulders. For shoulder widths between zero and 12 feet, the percent reduction in related accidents due to adding paved shoulders is 16 percent for 2 feet of widening, 29 percent for 4 feet of widening, and 40 percent for 6 feet of widening. Accident reductions due to adding unpaved shoulders were slightly less than for paved shoulders.

Safety effects of cross-section design for two-lane roads

Today’s transportation professionals are challenged to meet the mobility needs of an increasing population with limited resources. At many highway junctions, congestion continues to worsen. Drivers, pedestrians, and bicyclists experience longer delays and greater exposure to risk. Today’s traffic and safety problems are more complex and complicated. Conventional intersection/interchange designs are sometimes found to be insufficient to mitigate transportation problems. Consequently, many engineers are investigating and implementing innovative treatments in an attempt to think outside the box. This report covers four intersection designs and two interchange designs that may offer additional benefits compared to conventional at-grade intersections and grade-separated diamond interchanges. The six alternative treatments covered in this report are displaced left-turn (DLT) intersections, restricted crossing U-turn (RCUT) intersections, median U-turn (MUT) intersections, quadrant roadway (QR) intersections, double crossover diamond (DCD) interchanges, and DLT interchanges. The information presented in this report provides knowledge of each of the six alternative treatments including salient geometric design features, operational and safety issues, access management issues, costs, and construction sequencing and applicability.

Alternative Intersections/Interchanges: Informational Report (AIIR)

Signalized intersections on high-volume arterials are often congested during peak periods, causing a decrease in through movement efficiency on the arterial. Much of the vehicle delay incurred at conventional arterial intersections is caused by high left-turn demand. Unconventional inter section designs attempt to reduce intersection delay and travel times by rerouting left turns away from the main intersection. Seven unconventional designs—the quadrant roadway intersection, median U-turn, superstreet median, bowtie, jughandle, split intersection, and continuous flow intersection designs—that could apply to a wide range of standard, four-leg intersections are compared. Previous comparisons of intersection delay and travel time between conventional designs and these unconventional designs have been piecemeal and have largely used hypothetical volumes. Simulation experiments were conducted using turning movement data from seven existing intersections of varying sizes to compare the travel time of convention...

Joseph E. Hummer

Papers

Capacity for North Carolina Freeway Work Zones

Unconventional left-turn alternatives for urban and suburban arterials--part one

Safety effects of cross-section design for two-lane roads

Alternative Intersections/Interchanges: Informational Report (AIIR)

Travel Time Comparisons Between Seven Unconventional Arterial Intersection Designs