Wesley C. Zech

Effects of Vehicle Volume and Lane Closure Length on Construction Road User Costs in Rural Areas

The objective of this paper is to analyze the effects that vehicle volumes and lane closure lengths have on road user costs (RUCs) in rural freeway work zones. This paper presents a methodology developed to estimate RUCs for a rural four-lane freeway under construction with a single lane closure. Although the scenario presented is limited in its application to rural freeway construction projects, the methodology presented can be applied for any road construction project. Three tools have been developed as a result of this research: (a) a RUC template designed to calculate RUCs for a location on the basis of vehicle volumes, lane closure lengths, and speed values; (b) design graphs that practitioners can quickly reference to estimate RUCs for rural four-lane freeways with a single lane closure; and (c) regression equations derived from this research to quickly estimate RUCs. A practical and repeatable design method for estimating RUCs uses the results of this research. The design method can be used when time-based contractual provisions are developed on the basis of RUCs that are to be included in construction contracts for determining total project costs. When the method is used properly, it provides state highway agencies with a useful, justifiable way to calculate RUCs for single lane closure scenarios that can be used to develop incentive and disincentive provisions in rural roadway construction contracts.

Rapid Bridge Deck Replacement Construction Techniques: State of the Practice

Rapid bridge deck replacement (RBDR) is the method of replacing a bridge deck using innovative, alternative deck systems to perform needed repair under an accelerated construction schedule. Through employing RBDR techniques, state highway agencies (SHAs) can meet current transportation challenges by repairing the nations bridges while minimizing construction-related impacts. SHAs in the United States were surveyed on their experience with RBDR projects. Survey results are divided into the following categories: decision-making factors, construction schedules, construction techniques, contractual methods, costs, and innovations in safety or technology employed. Of the 52 responding agencies, 24 have experience with RBDR; 54% have less than 5 years of experience, and 63% have completed fewer than five RBDR projects, suggesting that the practice is new and most agencies are inexperienced. The strongest factors influencing decision making are traffic volume, critical bridge, safety, and impact on local business. Most RBDR projects are performed on highways and freeways, in both urban and rural areas. Lane closures are the most common closure scenario, which allows construction to proceed while maintaining partial throughput capacity. Most agencies use nighttime closures, which reduces road user impact and provides a safer environment. Although 86% of the responding agencies experienced an increase in construction costs, 68% agreed that RBDR projects are perceived as a cost-saving mechanism for road users. Information collected from this survey, along with lessons learned and safety and construction technologies employed, allow knowledge to be transferred to practitioners who may have little or no experience with RBDR techniques.

Evaluation of Wheat Straw Wattles for Velocity Reduction in Ditch Check Installations

Linear construction typically uses drainage conveyances to convey storm-water runoff away from construction sites to neighboring water bodies. These conveyances may be unstabilized and highly susceptible to erosive shear stresses associated with high-velocity flow. In certain situations, wattle ditch checks are used to help reduce channel erosion caused by high-velocity flow by creating an impoundment. However, with new technology emerging and limited scientific data available on the in-field performance of wattles, the quantification of an installations effectiveness for improving runoff control is difficult. The effectiveness of various configurations of wattle ditch check installations was investigated at the Auburn University Erosion and Sediment Control Testing Facility to help the Alabama Department of Transportation (DOT) improve the performance of wattle ditch checks. Results indicate that Alabama DOTs current installation practice of staking a wattle only to an unstabilized channel can be improved. The addition of a filter fabric underlay protects the channel bottom from scour at the installation area, and the use of sod staples coupled with a teepee staking pattern secures the wattle in place and increases ground contact, which reduces undercutting. This configuration ultimately minimizes highly erosive supercritical flows and maximizes the subcritical flow length by 99% compared with the base installation.

Robust Determination of Liquidated Damage Rates for State Highway Agencies

Liquidated damages (LDs) in highway construction contracts are daily monetary rates meant to compensate the owning agency for additional costs incurred because a project did not meet its completion date because of contractor delay. When LD provisions are challenged in court, provisions that lack proper documentation outlining the procedure used to determine rates have been deemed a penalty and unenforceable. This research effort sought to develop a methodology for developing a schedule of LD rates to be adopted by the Alabama Department of Transportation (ALDOT). The procedure outlined is to be used periodically to review and update the LD rates found in ALDOTs standard specifications for highway construction contracts, since their current schedule and review procedure has come under legal scrutiny. A statistically justifiable procedure was developed to calculate LD rates using historical project cost accounting data to create a traditional provision based on FHWA guidelines with the LD rates stipulated in a contract-size categorized table. The proposed procedure was then compared with a typical procedure used for developing LD rates. After comparisons, the proposed procedure stipulating LD rates in a table by contract value was determined to be the more robust method. The final product of this research is stepwise guidelines for practitioners to use on a periodic basis to review and update their schedule of LD rates.

Installation Enhancements to Common Inlet Protection Practices Using Large-Scale Testing Techniques

Inlet protection practices (IPPs) are temporary erosion and sediment controls commonly used in active construction sites to help reduce off-site transport of sediment. The overall in-field performance of these practices is commonly misunderstood. This study researched common failure modes of IPPs with the use of large-scale, channelized flow experiments. Testing evaluated the performance of standard IPP design details and provided installation enhancements to four typical practices commonly used in the erosion and sediment control industry (aggregate, sandbag, silt fence, and wattle barriers). Installation enhancements focused on providing effective structural improvements with typical installation materials while also considering reduced installation efforts and material costs. Enhancements increased IPPs impoundments while maintaining efficient dewatering times. Variations of practices from state agency design guides and comparisons of developed installation enhancements were presented. A performance and cost comparison was developed for practitioners to use when comparing improved IPPs.

Using Unmanned Aerial Vehicles to Conduct Site Inspections of Erosion and Sediment Control Practices and Track Project Progression

Construction activities increase the erosion potential of a site through earth-disturbing processes of vegetative grubbing, topsoil stripping, and grading. Receiving waters become susceptible and vulnerable to the process of sedimentation, which degrades the overall water quality. Federal, state, and local regulations require the use of erosion and sediment controls to help manage stormwater discharge from construction sites. Regulations further require regular inspections, monitoring, and maintenance of employed erosion and sediment control practices. Unmanned aerial vehicles (UAVs) are an emerging remote sensing tool capable of acquiring high resolution spatial and sensing data. Remote sensing with UAVs has the potential to provide high-quality aerial imagery and data that can assist in site inspections of erosion and sediment control practices and monitoring project progression. UAVs are economical and flexible in acquiring aerial data and can be preprogrammed with flight paths to capture data over construction sites objectively. UAV-based remote sensing enables user-controlled image acquisition and bridges the gap in scale and resolution between ground observations and imagery acquired from conventional manned aircraft and satellites. This research describes the application of UAV technologies for construction site inspections of erosion and sediment control practices and tracking project progression. A case study was performed on an active residential construction site with a commercially available UAV to showcase its application and capabilities of enhancing the site inspection process and construction monitoring.

Improving Distribution of Poultry Litter with Spinner Spreaders

As technology advances for applicators, it is assumed that the control and distribution of material should improve. A study was conducted to evaluate if real-time spinner disc control improves the distribution of poultry litter. A typical litter spreader equipped with an electronically adjustable hydraulic flow control (proportional) valve was used to test closed loop spinner-disc control and compare these results to a traditional manual valve, open-loop setup. Three application rates of 2242, 4483, 6725 kg/ha (1, 2, and 3 ton/acre, respectively) were selected. The litter was collected with using standard pans based on ASABE Standard S341.3 but modified to assess pattern uniformity using a two-dimension pan matrix. Analyses included assessing the variability and consistency of distribution patterns and spinner speeds. The single-pass distribution patterns produced by the manual valve were more symmetrical between the rates tested but demonstrated more variability than those of the proportional valve. Overlap patterns were also generated along with summary statistics to assess spread uniformity. The proportional valve patterns generated CV’s of 28.1%, 16.0%, and 13.4%, from low to high rates, respectively while the manual valve produced CV’s of 28.7%, 31.7%, and 29.5%, from low to high rates, respectively. The proportional valve maintained more consistent spinner speeds than the manual valve. Results indicated that closed-loop spinner control to maintain the desired speed provided improved distribution of poultry litter over the range of application rates tested.

Changes in Key Flexible Pavement Condition Measurements for Typical Warranty Periods

The Long-Term Pavement Performance (LTPP) DataPave database was used to extract pavement condition and limited structural information along with traffic data for 191 randomly selected new asphalt pavement sections from across the country. Pavement performance data were limited to the collection of longitudinal cracking in the wheelpaths, fatigue cracking, and transverse cracking. Rather than models for the type and extent of pavement distresses with age, a simplified process that coded the database for the first occurrence of a given distress in each of the 191 new test sections was developed. This approach was used to determine the percentage of pavements exhibiting a given type of distress at 3, 5, 7, 10, 15, and 20 years. The results indicate the following: at 3 years, no longitudinal, fatigue, or transverse cracking is present; at 5 years, less than 2% of the sections experienced longitudinal (wheelpath), fatigue, or transverse cracking; at 7 years, between 3% and 6% of the sections exhibited longitudinal, fatigue, or thermal cracking; at 15 years, approximately 50% of sections showed signs of cracking distresses; at 20 years, between 60% and 70% of the sections contained excessive cracking.

Full-Scale Performance Evaluations of Various Wire-Backed Nonwoven Silt Fence Installation Configurations

Silt fences have long been a key component for controlling construction stormwater runoff; nonetheless, many silt fence installations fail to perform in the field as intended. Silt fences are temporary sediment control measures used to retain sediment by impounding runoff and allowing for sedimentation on-site, while simultaneously discharging stormwater runoff at a controlled rate. This study evaluated the performance of eight alternative configurations of the Alabama Department of Transportation (ALDOT) standard wire-backed, nonwoven silt fence. Standard installation parameters associated with the ALDOT silt fence include (1) 32-in. (81.3-cm) high fence, (2) 0.95 lb/ft (1.4 kg/m) support T-post, and (3) 10 ft (3.0 m) T-post spacing. Throughout the series of configurations tested, these standard parameters were varied individually and jointly in efforts to improve overall performance. Variations to the standard parameters include (1) 24-in. (61.0-cm) high fence, (2) 1.25 lb/ft (1.9 kg/m) support T-post, (3) 5 ft (1.5 m) T-post spacing, and (4) trench offsetting. Performance analyses were conducted on each configuration and results were evaluated to determine the best overall configuration to enhance the in-field performance of the ALDOT silt fence. Ultimately, the offset 24 in. (61.0 cm) fence with 1.25 lb/ft (1.9 kg/m) T-post spaced 5 ft (1.5 m) on-center resulted in the best overall improvement, retaining an average of 93% of sediment and deflection of only 0.18 ft (0.004 m) over the course of three simulated storm events.

Modeling Highway Stormwater Runoff and Groundwater Table Variations with SWMM and GSSHA

AbstractHydrologic models are widely used to represent and study water flows in various land uses and environments. This paper presents work done to model stormwater runoff from a highway and fores...