Cost-Benefit Analysis of Sequential Warning Lights in Nighttime Work Zone Tapers, TPF-5(081), 2011

Improving safety at nighttime work zones is important because of the extra visibility concerns. The deployment of sequential lights is an innovative method for improving driver recognition of lane closures and work zone tapers. Sequential lights are wireless warning lights that flash in a sequence to clearly delineate the taper at work zones. The effectiveness of sequential lights was investigated using controlled field studies. Traffic parameters were collected at the same field site with and without the deployment of sequential lights. Three surrogate performance measures were used to determine the impact of sequential lights on safety. These measures were the speeds of approaching vehicles, the number of late taper merges and the locations where vehicles merged into open lane from the closed lane. In addition, an economic analysis was conducted to monetize the benefits and costs of deploying sequential lights at nighttime work zones. The results of this study indicates that sequential warning lights had a net positive effect in reducing the speeds of approaching vehicles, enhancing driver compliance, and preventing passenger cars, trucks and vehicles at rural work zones from late taper merges. Statistically significant decreases of 2.21 mph mean speed and 1 mph 85% speed resulted with sequential lights. The shift in the cumulative speed distributions to the left (i.e. speed decrease) was also found to be statistically significant using the Mann-Whitney and Kolmogorov-Smirnov tests. But a statistically significant increase of 0.91 mph in the speed standard deviation also resulted with sequential lights. With sequential lights, the percentage of vehicles that merged earlier increased from 53.49% to 65.36%. A benefit-cost ratio of around 5 or 10 resulted from this analysis of Missouri nighttime work zones and historical crash data. The two different benefitcost ratios reflect two different ways of computing labor costs.

Analysis of Existing Work-Zone Devices with MASH Safety Performance Criteria, TPF-5(018), 2009

Crashworthy, work-zone, portable sign support systems accepted under NCHRP Report No. 350 were analyzed to predict their safety peformance according to the TL-3 MASH evaluation criteria. An analysis was conducted to determine which hardware parameters of sign support systems would likely contribute to the safety performance with MASH. The acuracy of the method was evaluated through full-scale crash testing. Four full-scale crash tests were conducted with a pickup truck. Two tall-mounted, sign support systems with aluminum sign panels failed the MASH criteria due to windshield penetration. One low-mounted system with a vinyl, roll-up sign panel failed the MASH criteria due to windshield and floorboard penetration. Another low-mounted system with an aluminum sign panel successfully met the MASH criteria. Four full-scale crash tests were conducted with a small passenger car. The low-mounted tripod system with an aluminum sign panel failed the MASH criteria due to windshield penetration. One low-mounted system with aluminum sign panel failed the MASH criteria due to excessive windshield deformation, and another similar system passed the MASH criteria. The low-mounted system with a vinyl, roll-up sign panel successfully met the MASH criteria. Hardware parameters of work-zone sign support systems that were determined to be important for failure with MASH include sign panel material, the height to the top of the mast, the presence of flags, sign-locking mechanism, base layout and system orientation. Flowcharts were provided to assist manufacturers when designing new sign support systems.

Non-Destructive Evaluation of Iowa Pavements Phase 2: Development of a Fully Automated Software System for Rapid Analysis/Processing of the Falling Weight Deflectometer Data, 2009

The Office of Special Investigations at Iowa Department of Transportation (DOT) collects FWD data on regular basis to evaluate pavement structural conditions. The primary objective of this study was to develop a fully-automated software system for rapid processing of the FWD data along with a user manual. The software system automatically reads the FWD raw data collected by the JILS-20 type FWD machine that Iowa DOT owns, processes and analyzes the collected data with the rapid prediction algorithms developed during the phase I study. This system smoothly integrates the FWD data analysis algorithms and the computer program being used to collect the pavement deflection data. This system can be used to assess pavement condition, estimate remaining pavement life, and eventually help assess pavement rehabilitation strategies by the Iowa DOT pavement management team. This report describes the developed software in detail and can also be used as a user-manual for conducting simulation studies and detailed analyses. *********************** Large File ***********************

Integrated Risk Management for Improving Internal Traffic Control, Work-Zone Safety, and Mobility during Major Construction, TPF-5(081), 2012

Highway construction is among the most dangerous industries in the US. Internal traffic control design, along with how construction equipment and vehicles interact with the traveling public, have a significant effect on how safe a highway construction work zone can be. An integrated approach was taken to research work-zone safety issues and mobility, including input from many personnel, ranging from roadway designers to construction laborers and equipment operators. The research team analyzed crash data from Iowa work-zone incident reports and Occupational Safety and Health Administration data for the industry in conjunction with the results of personal interviews, a targeted work-zone ingress and egress survey, and a work-zone pilot project.

Synthesis of Work-Zone Performance Measures, TPF-5(081), 2013

The main objective of this synthesis was to identify and summarize how agencies collect, analyze, and report different work-zone traffic-performance measures, which include exposure, mobility, and safety measures. The researchers also examined communicating performance to the public. This toolbox provides knowledge to help state departments of transportation (DOTs), as well as counties and cities, to better address reporting of work-zone performance.

Effectiveness of Work Zone Intelligent Transportation Systems, TPF-5(081), 2013

In the last decade, Intelligent Transportation Systems (ITS) have increasingly been deployed in work zones by state departments of transportation. Also known as smart work zone systems they improve traffic operations and safety by providing real-time information to travelers, monitoring traffic conditions, and managing incidents. Although there have been numerous ITS deployments in work zones, a framework for evaluating the effectiveness of these deployments does not exist. To justify the continued development and implementation of smart work zone systems, this study developed a framework to determine ITS effectiveness for specific work zone projects. The framework recommends using one or more of five performance measures: diversion rate, delay time, queue length, crash frequency, and speed. The monetary benefits and costs of ITS deployment in a work zone can then be computed using the performance measure values. Such ITS computations include additional considerations that are typically not present in standard benefit-cost computations. The proposed framework will allow for consistency in performance measures across different ITS studies thus allowing for comparisons across studies or for meta analysis. In addition, guidance on the circumstances under which ITS deployment is recommended for a work zone is provided. The framework was illustrated using two case studies: one urban work zone on I-70 and one rural work zone on I-44, in Missouri. The goals of the two ITS deployments were different – the I-70 ITS deployment was targeted at improving mobility whereas the I-44 deployment was targeted at improving safety. For the I-70 site, only permanent ITS equipment that was already in place was used for the project and no temporary ITS equipment was deployed. The permanent DMS equipment serves multiple purposes, and it is arguable whether that cost should be attributed to the work zone project. The data collection effort for the I-70 site was very significant as portable surveillance captured the actual diversion flows to alternative routes. The benefit-cost ratio for the I-70 site was 2.1 to 1 if adjusted equipment costs were included and 6.9 to 1 without equipment costs. The safety-focused I-44 ITS deployment had an estimated benefit-cost ratio of 3.2 to 1.

Effects of Road Construction Intensity and Operations on Rural Freeway Work Zone Capacity, TPF-5(081), 2014

Capacity is affected by construction type and its intensity on adjacent open traffic lanes. The effect on capacity is a function of vehicles moving in and out of the closed lanes of the work zone, and the presence of heavy construction vehicles. Construction activity and its intensity, however, are not commonly considered in estimating capacity of a highway lane. The main purpose of this project was to attempt to quantify the effects of construction type and intensity (e.g. maintenance, rehabilitation, reconstruction, and milling) on work zone capacity. The objective of this project is to quantify the effects of construction type and its intensity on work zone capacity and to develop guidelines for MoDOT to estimate the specific operation type and intensity that will improve the traffic flow by reducing the traffic flow and queue length commonly associated with work zones. Despite the effort put into field data collection, the data collected did not show a full speed-flow chart therefore extracting a reliable capacity value was difficult. A statistical comparison between the capacity values found in this study using either methodologies indicates that there is an effect of construction activity on the values work zone capacity. It was found that the heavy construction activity reduces the capacity. It is very beneficial to conduct similar studies on the capacity of work zone with different lane closure barriers, which is also directly related to the type of work zone being short-term or long-term work zones. Also, the effect of different geometric and environmental characteristics of the roadway should be considered in future studies.

Calibration of Highway Safety Manual Work Zone Crash Modification Factors, TPF-5(081), 2014

The Highway Safety Manual is the national safety manual that provides quantitative methods for analyzing highway safety. The HSM presents crash modification factors related to work zone characteristics such as work zone duration and length. These crash modification factors were based on high-impact work zones in California. Therefore there was a need to use work zone and safety data from the Midwest to calibrate these crash modification factors for use in the Midwest. Almost 11,000 Missouri freeway work zones were analyzed to derive a representative and stratified sample of 162 work zones. The 162 work zones was more than four times the number of work zones used in the HSM. This dataset was used for modeling and testing crash modification factors applicable to the Midwest. The dataset contained work zones ranging from 0.76 mile to 9.24 miles and with durations from 16 days to 590 days. A combined fatal/injury/non-injury model produced a R2 fit of 0.9079 and a prediction slope of 0.963. The resulting crash modification factors of 1.01 for duration and 0.58 for length were smaller than the values in the HSM. Two practical application examples illustrate the use of the crash modification factors for comparing alternate work zone setups.

A Smartphone-Based Prototype System for Incident/Work Zone Management Driven by Crowd-Sourced Data, 2015

This project develops a smartphone-based prototype system that supplements the 511 system to improve its dynamic traffic routing service to state highway users under non-recurrent congestion. This system will save considerable time to provide crucial traffic information and en-route assistance to travelers for them to avoid being trapped in traffic congestion due to accidents, work zones, hazards, or special events. It also creates a feedback loop between travelers and responsible agencies that enable the state to effectively collect, fuse, and analyze crowd-sourced data for next-gen transportation planning and management. This project can result in substantial economic savings (e.g. less traffic congestion, reduced fuel wastage and emissions) and safety benefits for the freight industry and society due to better dissemination of real-time traffic information by highway users. Such benefits will increase significantly in future with the expected increase in freight traffic on the network. The proposed system also has the flexibility to be integrated with various transportation management modules to assist state agencies to improve transportation services and daily operations.

Wood waste processing in Iowa, 1996

The objective of this report is to gain a better understanding of the wood waste market in Iowa through surveying the processors of wood waste. A survey was sent out by the Iowa Department of Natural Resources Management Assistance Division to 147 public waste management organizations and private businesses with a questionnaire which asked for details of any wood waste processing operation.

Highway Work Zone Capacity Estimation Using Field Data from Kansas, TPF-5(081), 2015

Although extensive research has been conducted on urban freeway capacity estimation methods, minimal research has been carried out for rural highway sections, especially sections within work zones. This study attempted to fill that void for rural highways in Kansas, by estimating capacity of rural highway work zones in Kansas. Six work zone locations were selected for data collection and further analysis. An average of six days’ worth of field data was collected, from mid-October 2013 to late November 2013, at each of these work zone sites. Two capacity estimation methods were utilized, including the Maximum Observed 15-minute Flow Rate Method and the Platooning Method divided into 15-minute intervals. The Maximum Observed 15-minute Flow Rate Method provided an average capacity of 1469 passenger cars per hour per lane (pcphpl) with a standard deviation of 141 pcphpl, while the Platooning Method provided a maximum average capacity of 1195 pcphpl and a standard deviation of 28 pcphpl. Based on observed data and analysis carried out in this study, the suggested maximum capacity can be considered as 1500 pcphpl when designing work zones for rural highways in Kansas. This proposed standard value of rural highway work zone capacity could be utilized by engineers and planners so that they can effectively mitigate congestion at or near work zones that would have otherwise occurred due to construction/maintenance.

Implementation of the Federal Highway Administration Final Rule on Work Zone Safety and Mobility, 2007

The Federal Highway Administration published the final rule updating 23 CFR 630 Subpart J in September 2004. The revised rule requires agencies using federal funding to address both safety and mobility in planning and construction of roadway improvements. The Iowa Department of Transportation (Iowa DOT) requested the assistance of the Center for Transportation and Research in developing guidance for a policy and procedures to comply with the final rule. This report describes an in-depth examination of current Iowa DOT project development processes for all types of improvements, including maintenance, as well as a detailed characterization of work zone impact considerations throughout project completion. To comply with both the letter and perceived intent of the final rule on safety and mobility, the report features a suggested work zone policy statement and suggested revisions in the Iowa DOT project development processes, including a definition of the key element: significant projects.

Evaluation of Work Zone Speed Reduction Measures, 2000

The Iowa Department of Transportation (DOT) has made improving work zone (WZ) safety a high priority. Managing vehicle speeds through work zones is perceived to be an important factor in achieving this goal. A number of speed reduction techniques are currently used by transportation agencies throughout the country to control speeds and reduce speed variation at work zones. The purpose of this project is to study these and other applicable work zone speed reduction strategies. Furthermore, this research explores transportation agencies' policies regarding managing speeds in long-term, short-term, and moving work zones. This report consists of three chapters. The first chapter, a literature review, examines the current speed reduction practices at work zones and provides a review of the relevant literature. The speed control strategies reviewed in this chapter range from posting regulatory and advisory speed limit signs to using the latest radar technologies to reduce speeds at work zones. The second chapter includes a short write-up for each identified speed control technique. The write-up includes a description, the results of any field tests, the benefits and the costs of the technology or technique. To learn more about other state policies regarding work zone speed reduction and management, the Center for Transportation Research and Education conducted a survey. The survey consists of six multipart questions. The third chapter provides summaries of the response to each question.

Feasibility of Visualization and Simulation Applications to Improve Work Zone Safety and Mobility

Visualization is a relatively recent tool available to engineers for enhancing transportation project design through improved communication, decision making, and stakeholder feedback. Current visualization techniques include image composites, video composites, 2D drawings, drive-through or fly-through animations, 3D rendering models, virtual reality, and 4D CAD. These methods are used mainly to communicate within the design and construction team and between the team and external stakeholders. Use of visualization improves understanding of design intent and project concepts and facilitates effective decision making. However, visualization tools are typically used for presentation only in large-scale urban projects. Visualization is not widely accepted due to a lack of demonstrated engineering benefits for typical agency projects, such as small- and medium-sized projects, rural projects, and projects where external stakeholder communication is not a major issue. Furthermore, there is a perceived high cost of investment of both financial and human capital in adopting visualization tools. The most advanced visualization technique of virtual reality has only been used in academic research settings, and 4D CAD has been used on a very limited basis for highly complicated specialty projects. However, there are a number of less intensive visualization methods available which may provide some benefit to many agency projects. In this paper, we present the results of a feasibility study examining the use of visualization and simulation applications for improving highway planning, design, construction, and safety and mobility.

The Effect of the No-Passing Zone Sign on "Passing" Accidents, 1963

The No Passing Zone sign (Wl0-4) was designed in 1958 for the purpose of informing the driver contemplating a passing maneuver of hazardous sight conditions ahead. This warning sign, of pennent shape design, was placed on the left side of the road so as to be more conspicuous to the intended driver. During the two year period 1959-1960, the Wl0-4 signs were erected throughout the Iowa Primary Road System.