Louisiana Highway Research Articles

Research Implementation of AASHTOWare Pavement ME Design in Louisiana

Since the release of the first research version of Mechanistic–Empirical Pavement Design Guide software, the State of Louisiana has conducted a series of studies in preparation for adopting the new AASHTO design guide. The objective of this study was to develop an implementation guideline for the full implementation of the AASHTOWare Pavement ME Design program (Pavement ME) in Louisiana. For this purpose, a Louisiana default input strategy that reflected state and local conditions and practices was first developed. Design reliability and performance criteria were established on the basis of a consensus survey and pavement management system (PMS) distress triggers. A total of 162 projects were selected from the existing Louisiana highway network, including flexible pavements with five types of base, rigid pavements with three types of base, and rehabilitation with asphalt overlays. Performance data were retrieved from the PMS database and validated through additional field performance surveys. Through comparison of the performance predicted by the Pavement ME with the measured performance recorded in the PMS database, distress models were evaluated and calibrated according to local Louisiana conditions. Subsequently, a Louisiana Pavement ME Design Guideline that contains all necessary design input information and calibration coefficients was developed. Finally, the practical and economic benefits of the full implementation of the Pavement ME for Louisiana pavement design were demonstrated by a direct comparison with the current 1993 AASHTO design method through a group of thickness design examples and life-cycle cost analyses.

Louisiana motorcycle fatalities in the wake of governmentally implemented change

On August 15, 2004, Louisiana's universal motorcycle helmet mandate was reinstated. Previous studies have shown that mortality and morbidity of motorcycle riders who crashed had increased during the 5 years the mandate was repealed. The objective of this study was to discern whether the reinstatement of the universal helmet mandate has resulted in a subsequent decrease in motorcycle-related mortality and morbidity in the state of Louisiana. A retrospective analysis was performed observing the regularity of helmet use and the associated morbidity and mortality of motorcycle traffic accidents from the time before, during, and after the universal motorcycle helmet mandate was repealed in the state of Louisiana. Fatality statistics were obtained through the National Highway Safety Traffic Association. Injury, helmet use, and collision data were obtained from the Louisiana Highway Safety Commission. Motorcycle registration data were obtained from the Federal Highway Administration. Motorcycle crash-related fatalities increased significantly when the statewide helmet mandate was repealed, and interestingly, after reinstatement, these fatality rates never returned to their previous lows. Motorcycle fatalities have increased out of proportion to the increase in motorbike registrations, even when yearly fatalities are normalized to fatalities per 10,000 registered bikes. An all-time high in fatalities was seen in 2006, a year subsequent to the mandate's reinstatement. Fatalities per collision were elevated significantly after the mandate's repeal but did not return to prerepeal lows after the mandate's reinstatement. Although helmet use after reinstatement has reached all-time highs, fatality rates have remained elevated since the original mandate repeal in 1999. Other achievable changes in state policy and law enforcement should be explored to quell this heightened risk to motorcycle enthusiasts in Louisiana, and states considering changing their own motorcycle helmet legislation should observe keenly the aftermath of both a mandate repeal and reinstatement. Epidemiological study, level IV.

Louisiana Highway Construction Cost Trend after Hurricanes Katrina and Rita

The objective of this study was to reveal the trend in highway construction costs following Hurricanes Katrina and Rita in Louisiana. The means of measuring highway construction cost was the Louisiana Highway Construction Index, an index made up of the cost of labor, equipment, and six major materials used in highway construction. Data from projects let by the Louisiana Department of Transportation and Development from the second quarter of 2003 to the second quarter of 2007 were used to track the change in construction costs. Index values from hurricane-impacted areas (GO Zones) were compared with those in Non-GO Zones. The indices revealed that two quarters after Hurricanes Katrina and Rita, the highway construction cost jumped about 20% statewide and 51% in GO Zone. Two years after the hurricanes, the cost has stabilized to around 30% increase over the pre-Katrina and Rita period. This study provides valuable information for the state agency to estimate cost escalation in ongoing projects and to estima...

Louisiana Highway Evacuation Plan for Hurricane Katrina: Proactive Management of a Regional Evacuation

In the days preceding Hurricane Katrina in 2005, over one million people evacuated from southeast Louisiana. Preliminary evidence suggests that, given the few available routes and short advance warning, this achievement was the most successful highway-based evacuation in U.S. history. This paper presents the contraflow plan that was developed to evacuate the greater New Orleans area, the transportation goals and philosophies that underlie it, and the unique features that permitted it to be used so effectively. The plan was unprecedented in its size and scope. It required the closure of long segments of interstate freeway, forced movement of traffic onto alternative routes, established reversible flow segments of freeway that crossed state boundaries, forced coordination of parallel nonfreeway routes, and forced reconfiguration of busy urban freeway interchanges to more effectively load evacuees from the surface street network onto the interstate system. The lessons learned from this experience can be applied by emergency planning experts in their own jurisdictions.

Development of Database for Louisiana Highway Bridge–Scour Data

Scour of highway bridges in Louisiana has been collected and monitored since 1970. Approximately 120 bridges are being monitored at a frequency of one to several times per year with an average of six cross sections for each bridge. Consequently, a tremendous amount of scour data in the format of traditional paper files already exists for these bridges. Manual and visual analysis of data has been tedious work, and there existed a need to develop a computer program and a database system to perform scour-data management. Database-management software has been developed for storage, retrieval, and analysis of scour data of Louisiana highway bridges. The system stores the data in a database system within the network. A computer program was developed as a front-end to allow the user to access the database, retrieve the data via several search routines, plot the scour data for analysis, and perform data updates. The program compiles the on-site data collected during scour survey and the bridge data relevant to scour properties. It can be used in ( a) determining local scour at the piers and contraction scour at the bridge, ( b) analyzing the long-term changes in riverbed elevations at various locations in the site, ( c) providing the major parameters that are commonly used in bridgescour models for scour prediction, and ( d) evaluating site conditions and soil properties for scour repair. The program tabulates and plots the bridge information, pier data, and coordinates of the river cross sections at the survey locations. It displays survey maps and soil-boring data. The analysis of the bridge-scour data is performed using plots of the cross sections, longitudinal sections, and contour lines of the scour data. The history of the scour at any specific location is plotted in time plots. Further implementations of the database system are suggested for more accurate determination of potential scours in highway bridges.

Field and Laboratory Evaluation of the Use of Lime Fly Ash to Replace Soil Cement as a Base Course

The performance of lime and fly ash-stabilized base as an alternative to soil-cement-stabilized base for flexible pavement systems on reconstructed highways in Louisiana is evaluated in this study. Historically Louisiana has used soil cement for most flexible base construction because of its low cost, high compressive strength, and ease of construction. However, soil cement is subject to excessive cracking due to shrinkage, which may decrease the expected pavement life. Lime and fly ash bases exhibit many of the same properties as soil-cement bases with potential for less shrinkage cracking. Lime and fly ash (Class C fly ash) test sections were installed on two Louisiana highway reconstruction projects in the northwestern part of the state. For each project, two 0.4-km (0.25-mi) test sections with different percentages of lime and fly ash were constructed. The remainder of each project was constructed with 8 percent soil-cement base by volume. On both projects, the first test section used 2 percent lime and 4 percent fly ash by weight for stabilization and the second test section used 3 percent lime and 6 percent fly ash. Test specimens were molded in the field during construction by using stabilized base material taken from the roadway immediately before compaction. Laboratory test specimens were made later with materials taken from, but not mixed at, the construction sites. Both field and laboratory samples were tested in unconfined compression at 7, 28, and 56 days. The overall unconfined compressive strength of lime and fly ash was 30 percent lower than that of soil cement.

Moreau-Caminada Chenier Complex, Southeastern Louisiana: ABSTRACT

The Moreau-Caminada chenier complex south of New Orleans is the only sub-Holocene chenier system on the surface in Louisiana east of the classic western Louisiana cheniers. It occupies an area 16 km long and up to 5 km wide east of the mouth of Bayou Lafourche. About 60 ridges, 50-120 m wide and up to 7.5 km long, form the complex; the highest ridge elevation is only 1.2 m. Large new exposures along Louisiana Highway 1 revealed that the sand, which at places is at least 30 ft thick, is very fine grained and very well sorted. Detrital lignite grains make up as much as 7.6% of this chenier sand. Shell fragments, abundant in the western Louisiana cheniers, are absent. Autochthonous and detrital peat layers and laminae 1 mm or more thick are interlayered with the sand. Dating of three autochthonous peat samples from the Louisiana Construction Company and Plaisance Dragline and Dredging Company sand borrow pits revealed 2,940±120 to 2,340±120 years B.P. ages. Thus the cheniers are much older than the surrounding Lafourche- and Lafourche-Terrebonne subdelta sediments. After the last Lafourche distributary stream lost its water supply, substantial erosion started the destruction of the chenier complex. A coastal strip up to 2 km wide was eroded between 1890 and 1934, due to the closing off of the Bayou Lafourche discharge. New information about the Mississippi deltaic plain stratigraphy refutes suggestions that the southwest Louisiana chenier ridges formed during periods when the active delta lobes were on the other end of the deltaic plain. Seven sets of chenier ridges formed in the southwest Louisiana chenier plain between 2,800±600 B.P., while not only the distant St. Bernard distributaries were active but also the much closer Lafourche distributaries. The Moreau-Caminada cheniers were forming also in the proximity of one of the active Lafourche subdeltas. Cyclicity in chenier progradation should be attributed to fluctuations in local sediment supply and hydraulic conditions. Enough sediment must have been present in the littoral drift to prevent the wholesale erosion of the shore and to allow t e construction of ridges. Low ridge elevations in the Moreau-Caminada area are attributed to the great thickness of underlying post-Pleistocene sediments in contrast to the shallow Pleistocene surface in southwestern Louisiana. Shore recession in the chenier plain was accompanied by the reversal of littoral drift directions. The Moreau-Caminada cheniers indicate westward drift whereas the presently prevailing drift direction in the area is eastward. The present drift direction may date back to the construction of the Plaquemines subdelta End_Page 2041------------------------------ which since about 800 B.P. reduced the strength of the currents and waves from the east. Chenier ridge configurations depend primarily on the original outline of the shoreline and upon the conditions of sediment supply from the sea, from deltas, or from the estuaries. Different ridge patterns develop if the dominant littoral drift approach direction is similar or identical with that of the main sediment source area. In the present case a substantial part of the ridge sands came by the drift from the east, and most of the sediment probably came from the west, the area of an active Mississippi subdelta. A similar situation exists on the western bank of the Sabine Pass, eastern Texas, where the ridges developed from the southwest and most of the sediment supply came from the east with the prevailing drift and from the direction of Sabine Lake on the north. End_of_Article - Last_Page 2042------------

Owls on a Louisiana Highway

Owls on a Louisiana Highway