Highway Medians Research Articles

Highway Roadside and Median Green Belts Design Method Based on the Theory of Dynamic Vision

Unity and change are the basic principles of highway landscape design. Based on the investigation of highway revegetation, new concept of revegetation design was given. Bad roadside landscape should be sheltered by green belts, and beautiful roadside landscape should be divulged or showed by locally eliminating the green belts, and maximum length of green belts with single pattern should be limited for preventing drivers from dozing. Based on the theory of dynamic vision, this paper presents the formulas for computing the stake numbers of setting or eliminating the green belts according to the requirements of landscape design, and the formulas for computing the maximum length of green belts with single pattern. The results are helpful to the highway roadside and median green belts design.

Design and Research of a New Highway Median Guardrail Based on ANSYS

This paper reviewed of the development of highway guardrail status briefly, combined with the median guardrail design principles and requirements, then committed to design a new median guardrail which can improve the overall performance. By using finite element software ANSYS, the new guardrail imposed by the load which the size of the load force the same as auto collision impact, then observed the results to solve and test the strength of guardrail. At last, there was a prospect for future research.

Analyzing the influence of median cross-section design on highway safety using vehicle dynamics simulations

Although vehicle dynamics simulations have long been used in vehicle design and crash reconstruction, their use for highway design is rare. This paper investigates the safety of highway medians through iterative simulations of off-road median encroachments. The commercially available software CarSim was used to simulate over one hundred thousand encroachments, representing the entire passenger vehicle fleet and a wide range of encroachment angles, departure speeds, steering inputs, and braking inputs. Each individual simulation output was then weighted using data from previous studies to reflect the probability of each specific accident scenario occurring in a real-life median encroachment. Results of this analysis illustrate the relative influence of median cross-section geometry on the resulting accident outcomes. The simulations indicate that the overall safety of a highway median depends on the occurrence of both vehicle rollover and median crossover events, and the cross-section shape, slope, and width are all shown to greatly affect each of these incidents. An evaluation of the simulation results was conducted with vehicle trajectories from previous experimental crash tests. Further assessment of the aggregate simulation results to actual crash data was achieved through comparison with several databases of crash statistics. Both efforts showed a strong agreement between the simulations and the real-life crash data.

First Report of Xylella fastidiosa Associated with Oleander Leaf Scorch in Louisiana.

Oleander (Nerium oleander L.) is an evergreen shrub native to the Mediterranean Region and Southeast Asia. Despite being poisonous, it is a popular ornamental plant for use in landscapes, gardens, parks, roadsides, and highway medians. During the fall of 2008, several oleander plants with leaf scorch symptoms were observed at Arsenal Park in Baton Rouge, LA. Symptomatic oleander samples were also received from a commercial nursery in Baton Rouge, LA and a homeowner in Thibodeaux, LA. Symptoms resembled leaf scorch caused by Xylella fastidiosa Wells et al. and included chlorotic mottling of the leaves that started from the tips and margins and progressed toward the midribs. As disease developed, leaf tips and margins became necrotic. Severely infected plants defoliated and died. Leaf petioles from 13 samples (8 from Arsenal Park, 3 from the commercial nursery, and 2 from the homeowner) from symptomatic plants gave positive reactions for X. fastidiosa by ELISA (Agdia, Inc., Elkhart, IN). Leaf petioles from six healthy oleander plants gave a negative reaction for X. fastidiosa by ELISA. Isolation of X. fastidiosa was attempted from eight ELISA-positive and six ELISA-negative oleander samples. Leaf petioles weighing 0.05 g from each sample were used for isolation. The petioles were surface sterilized in 70% ethanol for 1.5 min and then in 2% sodium hypochlorite for 1.5 min, followed by three 1-min washes in sterile water. The petioles were chopped into small pieces under aseptic conditions and soaked in 500 μl sterile water for 30 min. One hundred microliters of the suspension were spread onto periwinkle wilt (PW) plates and incubated in the dark at 28°C. After incubation for 7 days, bacterial colonies typical of X. fastidiosa appeared on five of eight ELISA-positive sample plates. No colonies were observed on six ELISA-negative sample plates. Single colonies were transferred to fresh PW plates to obtain pure cultures. Bacterial colonies from five pure cultures were suspended in nuclease-free water and boiled for 10 min to obtain DNA. DNA from eight symptomatic and six healthy oleander plants was extracted with a DNeasy Plant Mini kit (Qiagen Inc., Valencia, CA) according to the manufacturer's guidelines. Primers (QHOLS-08 and QHOLS-05) (1) specific to the oleander strain of X. fastidiosa amplified a 274-bp portion of DNA from both symptomatic oleander tissues and pure culture of X. fastidiosa isolated from symptomatic tissue. No such amplification was observed in healthy tissue. These primers amplify a portion of DNA encoding a hypothetical protein of unknown function that has been shown to be unique to oleander strains of X. fastidiosa. The PCR product was sequenced and compared with the whole genome shotgun sequence of the oleander strain Ann-1 of X. fastidiosa (GenBank Accession No. AAAM03000099), which resulted in 100% identity with nucleotides 11343 to 11616 in contig 228. X. fastidiosa has been previously reported to cause oleander leaf scorch in California (3), Florida (4), and Texas (2). To our knowledge, this is the first report of X. fastidiosa associated with oleander leaf scorch in Louisiana, extending the geographic range of this important bacterial disease.

Native Perennial Grasses in Highway Medians: Pre- and Postplant Techniques for Establishment in a Mediterranean Climate

AbstractWithin highway rights-of-way, native perennial grasses provide desirable services to support natural and human constructed ecosystems. However, native perennial grass establishment in annual grass dominated roadsides of semiarid and Mediterranean climates of the western United States requires specific cultural and chemical management treatments to control weeds. In 2004, field studies were conducted in Sacramento Valley, California to determine the effect of herbicide, disc cultivation, and species selection on native perennial grass establishment and annual weed persistence. Perennial grass species mixes common to drier and wetter upland areas in northern California were drill seeded at two sites (I-5 North and I-5 South) that had been burned in 2003 and received weed control (i.e., herbicide, cultivation, mowing) in spring 2004. Herbicides were the most important treatments for native perennial grass establishment and weed reduction. Native perennial grass species persistence was largely unaffected by cultivation or native plant accessions at these sites. Native perennial grass density increased at I-5 North in the second year of growth (2006) resulting in a plant density totaled across all herbicide regimes of 3.9 plants m−1 compared to 2.5 plants m−1 at I-5 South. Vigorous native perennial grass growth in the more fertile and less droughty soils of I-5 North helped to limit annual weeds through competition, which is anticipated to reduce the need for chemical and mechanical control in years following early establishment.

Emergency Psychiatry in Houston: Caring for Victims of the Katrina Catastrophe

Emergency Psychiatry in Houston: Caring for Victims of the Katrina Catastrophe

Emergency Psychiatry in Houston: Caring for Victims of the Katrina Catastrophe

Emergency Psychiatry in Houston: Caring for Victims of the Katrina Catastrophe

Effects of Rural Highway Median Treatments and Access

The safety records of rural and suburban four-lane highways in Arkansas as a function of median treatment and access density were examined. The study excluded roadways with posted speeds lower than 64 km/h (40 mph) and excluded fully controlled access roadways. When entering an urban area, the segments were normally terminated when the first traffic signal or stop sign was encountered. By using 3 years of crash data, the analyses revealed a number of relationships relating crash frequency to median, volume, and access frequency attributes. Crash severity and crash type were also examined. As median width increased, there was a weak but statistically significant decline in the crash rate. There was a weak but statistically significant increase in the crash rate as access density increased. The roadways with shoulders and depressed medians had the lowest crash rates, and the roadways with no median (i.e., painted centerline) and curbs had the worst safety record. An inspection of these data suggests that there may be a correlation between median type and land use type: certain types of median are more likely to be present in certain land use environments. This raises the possibility that in this and in other studies of the safety effects of median treatments, the findings may be influenced or skewed by correlations between median type and land use or surroundings or by other factors.

Effects of Rural Highway Median Treatments and Access

The safety records of rural and suburban four-lane highways in Arkansas as a function of median treatment and access density were examined. The study excluded roadways with posted speeds lower than 64 km/h (40 mph) and excluded fully controlled access roadways. When entering an urban area, the segments were normally terminated when the first traffic signal or stop sign was encountered. By using 3 years of crash data, the analyses revealed a number of relationships relating crash frequency to median, volume, and access frequency attributes. Crash severity and crash type were also examined. As median width increased, there was a weak but statistically significant decline in the crash rate. There was a weak but statistically significant increase in the crash rate as access density increased. The roadways with shoulders and depressed medians had the lowest crash rates, and the roadways with no median (i.e., painted centerline) and curbs had the worst safety record. An inspection of these data suggests that there may be a correlation between median type and land use type: certain types of median are more likely to be present in certain land use environments. This raises the possibility that in this and in other studies of the safety effects of median treatments, the findings may be influenced or skewed by correlations between median type and land use or surroundings or by other factors.

The Charm of the Highway Median

The Charm of the Highway Median

In the Aftermath of Tragedy

In the Aftermath of Tragedy

Performance of Vegetative Controls for Treating Highway Runoff

Vegetative storm water controls include grassed swales and vegetated filter strips. The effectiveness of these controls for removing pollutants found in runoff from highways and other urban areas has not been demonstrated to the satisfaction of regulatory agencies; therefore, these technologies have been limited to applications as pretreatment devices for other structural runoff controls. Many highways in Texas and other areas discharge storm water to grassy medians and shoulder areas, which act as both filter strips and grassed swales. The runoff flows overland down the sides of the median as in a filter strip and then parallel to the highway as in a grassed swale. This study investigated the capability of vegetated highway medians for treating storm water runoff in the Austin, Tex. area. Two medians on major highways were monitored to document pollutant removal efficiencies. The medians were designed solely for storm water conveyance and differed in slope and vegetation type. In addition, the highways a...

Factors Affecting Accumulation of Deicing Salts in Soils Around Trees

Parkways, street tree planter boxes, and highway medians and roadsides are locations where soil accumulation of deicing salts is highest. Sodium chloride is the most common deicer applied in the United States. Sodium chloride and other salts accumulating in the root zone may instigate and exacerbate street tree decline. Salts affect soil aggregate stability, porosity, and water and nutrient uptake in trees. Data collected in Chicago, Illinois show much higher soil sodium (1,272 jxg/g) and chloride (348 |ig/g) in the center of newly installed, narrow, raised medians along Lake Shore Drive after one winter, compared to the center of wide medians along the roadway (236 ng/g sodium and 23 (ig/g chloride). Proximity to high speed traffic and its associated spray and splash were reasons for this. In suburban Downers Grove, Illinois, grade level street tree planter soils had extremely high levels of sodium (1,426 |ig/g to 2,277 |ig/g) compared to adjacent raised planter soils. The raised planters did not receive saltladen runoff, splash, plowed snow, or direct application from salt spreaders.

Control of Bagworms on Eastern Red Cedar, 1987

Abstract This experiment was conducted on an eastern red cedar hedge located in a highway median in Lexington, Ky. The plants (8-10 ft tall) were pruned to isolate 24 individual 3-ft branches. The experimental design was a randomized complete block with 6 replications. Bases of branches were banded with Tangletrap to confine experimental larvae. On 14 Jul, bagworms collected from another site were placed on the foliage and allowed to acclimate for 24 h, after which they were culled to 10 larvae/branch. Insecticides were then applied to the point of runoff. The number of live bagworms remaining on each branch was determined on 18 Jul. To test for residual toxicity, 5 additional bagworms were placed on test branches on 21 Jul (1 wk after treatment) and evaluated for survival on 24 Jul.

Small Mammal use of an Interstate Highway Median Strip

Small Mammal use of an Interstate Highway Median Strip

Shading Effects on Growth and Partitioning of Plant Biomass in Cogongrass (Imperata cylindrica) from Shaded and Exposed Habitats

The growth responses of cogongrass [Imperata cylindrica(L.) Beauv.] were studied in a controlled-environment greenhouse with a day/night temperature of 29/23 C, under full available light and 56 and 11% of full light. The cogongrass plants were grown from stem and rhizome propagules originating from an interstate highway median, a pecan [Carya illinoensis(Wangenh.) K. Koch] plantation, and a pine (Pinusspp.) forest. After 89 days, the plants from all three populations produced, on average, three times as much total dry weight and leaf area in full available sunlight as in 56% full light and 20 times as much as in 11% full light. The distribution of plant biomass into rhizomes decreased with shading, whereas the distribution into leaves increased. The distribution of leaf biomass as leaf area also increased with shading, with the result that the plants grown in 11% full light had leaf area ratios about 2.5 times greater than those grown in full light. Reductions in dry matter production with shading were due to significant reductions in both net assimilation rate and leaf area duration or total amount of leaf area present. The plants from the shaded and exposed habitats generally did not differ significantly in their responses to shading. Thus, there is little evidence for the presence of sun and shade ecotypes in the populations of cogongrass studied.

Summer Behavior of Immature Radio-Equipped Woodcock in Central Maine

The behavior of 15 immature American woodcock (Philohela minor) was studied in central Maine during the summers of 1969 and 1970 using radiotelemetry. The monitored birds used a variety of nocturnal sites including old fields, bogs, powerlines, highway medians, woods roads, and forest clearings. Old fields were occupied more often than any other type of opening. Second growth-hardwoods, alders, hardwood-conifers, and conifers were utilized as diurnal cover. Diurnal locations of radioequipped woodcock averaged 15 m from major breaks in the forest canopy. Four birds were monitored continuously during the day and night to determine periods of activity. Although the birds were active throughout the day, very little activity was recorded after they moved to nocturnal sites. No apparent difference was found in the daily patterns of movement between immature male and female woodcock. Crepuscular movements between diurnal covers and nocturnal areas averaged 332 m. A composite summer range for the 15 woodcock during 183 woodcock-days was 1060 hectares. The data suggest that immature woodcock are quite mobile during the summer and utilize most of the forest openings occurring within 1-3 km of good nesting habitat. Most of these openings are also used for singing grounds by males in the spring. J. WILDL. MANAGE. 37(4):462-469 The behavior of immature (hatching-year) woodcock was investigated using radiotelemetry during September 1969, and from June to September 1970. The objectives of the study were to determine the summer movements of immature woodcock, and to investigate temporal patterns of behavior, such as feeding and resting, while in diurnal coverts and on nocturnal fields. These aspects of summer behavior are little known despite many previous studies (Pettingill 1936; Mendall and Aldous 1943; Sheldon 1961, 1967; Krohn 1970, 1971; Liscinsky 1972). Our appreciation is extended to the following for their aid in planning and implementing this study and reviewing this paper: H. L. Mendall, Maine Cooperative Wildlife Research Unit; M. W. Coulter and S. D. Schemnitz, University of Maine; J. Peppard, Maine Department of Inland Fisheries and Game; and W. B. Krohn, U.S. Bureau of Sport Fisheries and Wildlife. We also express our thanks to the wildlife students at the University of Maine who helped with the field work and to J. W. Morgan for technical assistance. This study was supported by the U.S. Bureau of Sport Fisheries and Wildlife through contract No. 14-160008-945A with the Maine Department of Inland Fisheries and Game and the Univer-

Wooded Highway Medians

Wooded Highway Medians