Shauna Hallmark

Use Of Remote Sensing For Collection Of Data Elements For Linear Referencing SystemsPage 2 2. INTRODUCTION........................................................................................................ 5 2.1 Linear Referencing.................................................................................................... 5

Rural curves are known to pose a significant safety problem, but the interaction between the driver and roadway environment is not well understood. Thus, the objective of this research was to assess the relationship between driver behavior and characteristics, roadway factors, environmental factors, and the likelihood of roadway departures on rural two-lane curves. To accomplish this, data from the second Strategic Highway Research Program (SHRP 2) Naturalistic Driving Study (NDS) and Roadway Information Database (RID) were used to develop relationships between driver, roadway, and environmental characteristics and the risk of a roadway departure on curves. This research was tailored to address four fundamental research questions: What defines the curve area of influence? What defines normal behavior on curves? What is the relationship between driver distractions; other driver, roadway, and environmental characteristics; and risk of roadway departure? Can lane position at a particular state be predicted as a function of position in a prior state? Since four fundamental research questions were addressed, a different methodology was developed specific to each. In addition to the analytical method, the data sampling and segmentation approach, general variables considered, results, and implications are discussed for each question.

The growing number of schoolchildren being dropped off or picked up in private vehicles poses significant challenges related to student safety and traffic operations in school zones. These private vehicles must compete for space at schools with buses, bicycles, and pedestrians. This study uses on-site observations, traffic data collection, and interviews with schools, law enforcement and traffic engineers to identify transportation safety issues at elementary school sites in Iowa. Some problems frequently observed included crossing at unmarked crosswalks, unloading and loading students on the street-side, inattentive student safety patrols, and illegal parking. A range of recommendations for mitigating these problems are suggested. The recommendations include separation of transportation modes, the development of a structured arrival and dismissal protocol for parents and students, and frequent communication with parents and students about the school's expectations for the before and after school periods.

The Federal Highway Administration (FHWA) estimates that 58 percent of roadway fatalities are lane departures, while 40 percent of fatalities are single-vehicle run-off-road (SVROR) crashes. Addressing lane-departure crashes is therefore a priority for national, state, and local roadway agencies. Horizontal curves are of particular interest because they have been correlated with increased crash occurrence. This toolbox was developed to assist agencies address crashes at rural curves. The main objective of this toolbox is to summarize the effectiveness of various known curve countermeasures. While education, enforcement, and policy countermeasures should also be considered, they were not included given the toolbox focuses on roadway-based countermeasures. Furthermore, the toolbox is geared toward rural two-lane curves. The research team identified countermeasures based on its own research, through a survey of the literature, and through discussions with other professionals. Coverage ...

The primary objective of this toolbox is to summarize various known traffic-calming treatments and their effectiveness. This toolbox focuses on roadway-based treatments for speed management, particularly for rural communities with transition zones. Education, enforcement, and policy strategies should also be considered, but are not the focus of this toolbox. The research team identified treatments based on their own research, a review of the literature, and discussion with other professionals. This toolbox describes each treatment and summarizes placement, advantages, disadvantages, effectiveness, appropriateness, and cost for each treatment. The categories of treatments covered in this toolbox are as follows: horizontal physical displacement, vertical physical displacement, narrowing, surroundings, pavement markings, traffic control signs, and other strategies.

The objective of this project was to evaluate low-cost measures to reduce speeds on high-crash horizontal curves. The researchers evaluated two low-cost treatments in Iowa to determine their effectiveness in reducing speeds on rural two-lane roadways. This report summarizes how the research team selected sites and collected data, and the results. The team selected six sites. Retroreflective post treatments were added to existing chevrons at four sites and on-pavement curve markings were added at two sites. The researchers collected speed data before and after installation of the two treatments. The study compared several speed metrics to assess the effectiveness of the treatments. Overall, both were moderately effective in reducing speeds. The most significant impact of the treatments was in reducing the percentage of vehicles traveling over the posted or advisory speed by 5, 10, 15, or 20 or more mph. This result suggests that the treatments are most effective in reducing high-end ...

New vehicle modal emissions rate models will assess emissions as a function of specific operating mode or engine load surrogates. These new models require that vehicle activity be input by fraction of time spent in different operating modes. However, the ability to realistically model onroad modal vehicle activity currently limits the implementation of these models. Few data on how vehicles operate in a real-world setting exist. Simulation models offer attractive advantages for modal modeling. They are readily available and generally can be used with both simple and detailed data input. Simulation models were developed to model the impacts of signal timing, incidents, or design features on traffic flow and perform well for these applications. However, simulation models, such as CORSIM, use theoretical profiles of vehicle acceleration and speed relationships that have not been validated in the field. To determine the feasibility of using simulation models to predict on-road speedacce...

Pavement edge drop-off can be a serious safety concern when a vehicle leaves the paved 18 roadway surface and encounters a significant vertical elevation difference between the paved 19 roadway and the adjacent unpaved shoulder. Edge drop-offs are potential ...

Fuel costs are a significant portion of transit agency budgets. Hybrid buses offer an attractive option and have the potential to reduce operating costs for agencies significantly. Hybrid technology has been available in the transit market for some time. As of 2009, there are more than 1,200 hybrid buses in regular service in North America in more than 40 transit agencies (Transport Canada 2011). The majority of these buses are regular 40 ft buses, although some smaller (20 ft) shuttle buses and larger articulated (60 ft) buses are also in service. The transit agency in New York, New York has approximately 1,000 hybrid vehicles as of 2009 (Maynard 2009) and Toronto, Canada has approximately 33 percent (Transport Canada 2011). The main reasons agencies consider hybrid transit vehicles are fuel savings and reduced emissions. Hybrid electric buses offer an attractive option and have the potential to reduce operating costs for transit agencies significantly. Wayne et al. (2009) estimate...

A number of traffic-calming devices were evaluated to determine their effectiveness in reducing speeds along the main road through a small rural community. Five different treatments were selected and installed in six rural Iowa communities. This tech brief highlights use of temporary curbing to create center islands. Pneumatic road tubes were used to collect speed and volume data before and after installation of the rural traffic calming treatments. Data were typically collected for 48 hours on a Monday through Friday under mostly dry weather conditions. Speeds decreased at two sites with decreases up to 2.2 mph in mean speed and up to 3 mph in 85th percentile speed. The fraction of vehicles traveling 5 or more mph over the posted speed limit decreased by 29 percent and the fraction of vehicles traveling 10 or more mph over decreased by 29 to 46 percent. A large decrease (up to 71 percent) resulted in the fraction of vehicles traveling 15 or more mph over the posted speed limit. The...

A number of traffic-calming devices were evaluated to determine their effectiveness in reducing speeds along the main road through a small rural community. Five different treatments were selected and installed in six rural Iowa communities. This tech brief highlights use of transverse speed bars. Pneumatic road tubes were used to collect speed and volume data before and after installation of the rural traffic-calming treatments. Data were typically collected for 48 hours on a Monday through Friday under mostly dry weather conditions. Typical speed statistics, such as change in average speed, were calculated for each location where data were collected. Speeds decreased at two of the three sites with decreases of 1 mph in mean and 85th percentile speeds. The fraction of vehicles traveling 5 or more mph over the posted speed limit decreased by about 8 percent and the fraction of vehicles traveling 10 or more mph over decreased by 12 percent for both sites. A large decrease resulted in ...

The Institute of Transportation Engineers Traffic Engineering Council technical committee conducted a survey on school-related traffic control devices in early 2007. The 37-question survey gathered information on: the state-of-the-practice for school speed zones, signing and markings for schools, and engineering judgment on when to install a school speed zone. A total of 168 participants provided responses and this paper contains a summary of the findings for each question.

Background Small rural communities often lack the expertise and resources necessary to address speeding and the persistent challenge of slowing high-speed through traffic. The entrances to communities are especially problematic given that drivers must transition from a high-speed, often-rural roadway setting to a low-speed community setting. The rural roadway provides high-speed mobility outside the community, yet the same road within town provides local access and accommodates pedestrians of all ages, on-street parking, bicycles, and other features unique to the character of a small community. Drivers who have been traveling for some distance on the high-speed road, and are traveling through the community, may not receive the appropriate clues that the character of the roadway is changing and may not adjust their speeds appropriately. Addressing speeding issues is an even greater challenge given that smaller communities typically lack engineering staff and resources, which can lead

About 56% of traffic fatalities in the US are roadway departures. In 2013, this represented 18,257 fatalities (FHWA 2014). One contributor to roadway departure crashes is the presence of pavement edge drop-off, which is a vertical elevation difference between two adjacent roadway surfaces. Edge dropoffs are potential safety hazards because significant vertical differences between surfaces can reduce vehicle stability and impede the driver’s ability to handle their vehicle (Ivey et al. 1984). A typical pavement edge drop-off-related crash occurs when the driver attempts an immediate return to the roadway and tire scrubbing occurs.

In work-zone configurations where lane drops are present, merging of traffic at the taper presents an operational concern. In addition, as flow through the work zone is reduced, the relative traffic safety of the work zone is also reduced. Improving workzone flow-through merge points depends on the behavior of individual drivers. By better understanding driver behavior, traffic control plans, work zone policies, and countermeasures can be better targeted to reinforce desirable lane closure merging behavior, leading to both improved safety and work-zone capacity. The researchers collected data for two work-zone scenarios that included lane drops with one scenario on the Interstate and the other on an urban arterial roadway. The researchers then modeled and calibrated these scenarios in VISSIM using real-world speeds, travel times, queue lengths, and merging behaviors (percentage of vehicles merging upstream and near the merge point). Once built and calibrated, the researchers modeled...

The objective of these web pages is to synthesize safety research to address the top traffic safety needs in Iowa. Information about roadway departures, rural intersections, and rural speed management relevant to Iowa is summarized to help agencies more effectively target specific types of crashes in Iowa.

Rural intersections account for 30% of crashes in rural areas and 6% of all fatal crashes, representing a significant but poorly understood safety problem. Transportation agencies have traditionally implemented countermeasures to address rural intersection crashes but frequently do not understand the dynamic interaction between the driver and roadway and the driver factors leading to these types of crashes. The Second Strategic Highway Research Program (SHRP 2) conducted a large-scale naturalistic driving study (NDS) using instrumented vehicles. The study has provided a significant amount of on-road driving data for a range of drivers. The present study utilizes the SHRP 2 NDS data as well as SHRP 2 Roadway Information Database (RID) data to observe driver behavior at rural intersections first hand using video, vehicle kinematics, and roadway data to determine how roadway, driver, environmental, and vehicle factors interact to affect driver safety at rural intersections. A model of ...

In the US, some states have begun to address rural high-speed intersection crashes by physically restricting minor-road crossing movements (left and through turns) to simplify driver decision-making in terms of gap acceptance (the extent to which drivers will be able to utilize a gap in traffic of a particular size or duration). These treatments are referred to in Minnesota as reduced conflict intersections (RCIs).

U.S. Geological Survey (USGS) based elevation data are the most commonly used data source for highway hydraulic analysis; however, due to the vertical accuracy of USGS-based elevation data, USGS data may be too "coarse" to adequately describe surface profiles of watershed areas or drainage patterns. Additionally hydraulic design requires delineation of much smaller drainage areas (watersheds) than other hydrologic applications, such as environmental, ecological, and water resource management. This research study investigated whether higher resolution LIDAR (light detection and ranging) based surface models would provide better delineation of watersheds and drainage patterns as compared to surface models created from standard USGS-based elevation data. Differences in runoff values were the metric used to compare the data sets. The two data sets were compared for a pilot study area along the Iowa 1 corridor between Iowa City and Mount Vernon. Given the limited breadth of the...

Dynamic speed feedback sign (DSFS) systems are traffic control devices that are programmed to provide a message to drivers exceeding a certain speed threshold. A DSFS system typically consists of a speedmeasuring device, which may be loop detectors or radar, and a message sign that displays feedback to drivers who exceed a predetermined speed threshold. The feedback may be the driver’s actual speed, a message like “SLOW DOWN,” or activation of a warning device such as beacons or a curve warning sign. For more on this topic by these authors, see also "Evaluation of Dynamic Speed Feedback Signs on Curves: A National Demonstration Project": http://www.trb.org/main/blurbs/172092.aspx

Chevrons provide additional emphasis and guidance for drivers. If spaced properly, chevrons can delineate the curve so drivers can interpret the sharpness of the curve. Table 2C-2 of the Manual on Uniform Traffic Control Devices (FHWA 2009a) recommends the size of chevron alignment (W1-8) signs by roadway type. Several agencies, including the Iowa Department of Transportation (Iowa DOT), have applied a larger chevron size to a roadway than suggested by this table. The idea is that larger chevrons will be more prominent and visible to drivers. These larger chevrons may be particularly useful if sight distance issues exist.

Abstract Objective: Using naturalistic driving data, this study analyzed the driving behavior of major approach right and left turning vehicles to minor approach at rural two-way stop controlled intersections by detecting the location where drivers reacted to the upcoming intersection to complete a turning maneuver. Methods: The study used 449 time series traces from 29 two-way stop controlled intersections across five states for the analysis. All 449 traces were associated to free flow condition with driving not obstructed by the vehicle ahead. Each time series trace was analyzed to check the point drivers first reacted to the intersection for the turning maneuver and this point was called the reaction point. Braking Behavior of Major Approach Turning Vehicles at Rural Two-Way Stop Controlled Intersections: A Naturalistic Driving Study Results: The results from this study showed that right turning vehicles began reacting, in general, sooner than left turning vehicles. More than 75% of drivers showed a reaction within 300 meters upstream of intersection for both types of turning maneuver. The study found driving speed at the reaction point significantly affecting the initial point of reaction. Drivers who were traveling faster than the posted speed limit were associated with a reaction point farther upstream than vehicles traveling at the speed limit. On-pavement marking upstream of the intersection was found to be associated with longer reaction distance, while posted intersection ahead warning signs showed a reverse effect. The result provides information on braking zone of turning vehicles at intersections which has implication on the placement of different countermeasures upstream at the major approach. Conclusions: By detecting reaction distance of all 449 time series trace, the study provides an influence area of the intersection for the turning vehicles.

Rural intersections account for around 30% of crashes in rural areas and 6% of all fatal crashes. An Intersection Conflict Warning System (ICWS) is a unique solution to address rural intersection safety. ICWS are typically installed at the minor approaches to two-way stop-controlled intersections to reduce the number of fatalities. Studies indicate these systems result in lower intersection approach speeds, reduced conflicts, and improved driver-gap selection. However, some sites have experienced increases in the number of minor crashes. Although there are positive ICWS examples, their overall effectiveness is not well established. The objective of this research was to evaluate driving behavior at stop-controlled approaches with and without ICWS and to evaluate the spillover effect of ICWS on other adjacent control intersections where the treatment has not been applied. The study examined behavior at five intersections (treatment sites) in Minnesota where an ICWS was installed. For ...

Horizontal curves have been shown to exhibit crash rates significantly higher than comparable tangent segments. Extensive research has investigated the causes of crashes on horizontal curves, particularly the curve navigation process and driver speed selection. Research in this area has generally been limited by the nature of the data, which is often inhibited by practical constraints as to the number of locations and drivers that can be observed. This study overcomes these hurdles through the use of naturalistic driving data, providing insights on how drivers navigate and react to curves on rural two-lane highways. Nearly 10,000 vehicle traces were collected from 202 drivers on 219 horizontal curves as a part of this study. All driving traces were collected on rural two-lane highways with prevailing posted speed limits of 45 mph or 55 mph, as well as a diverse range of curve advisory speeds. Regression models are estimated via generalized estimating equations to discern those facto...

Prior research has shown the probability of a crash occurring on horizontal curves to be significantly higher than on similar tangent segments, and a disproportionally higher number of curve-related crashes occurred in rural areas. Challenges arise when analyzing the safety of horizontal curves due to imprecision in integrating information as to the temporal and spatial characteristics of each crash with specific curves. The second Strategic Highway Research Program(SHRP 2) conducted a large-scale naturalistic driving study (NDS),which provides a unique opportunity to better understand the contributing factors leading to crash or near-crash events. This study utilizes high-resolution behavioral data from the NDS to identify factors associated with 108 safety critical events (i.e., crashes or near-crashes) on rural two-lane curves. A case-control approach is utilized wherein these events are compared to 216 normal, baseline-driving events. The variables examined in this study include...

This report updates the Federal Highway Administration's "Roundabouts: An Informational Guide" based on experience gained in the United States since that guide was published in 2000. The report addresses the planning, design, construction, maintenance, and operation of roundabouts. It also includes information that will be useful in explaining to the public the trade-offs associated with roundabouts.

A large number of rural crashes occur on curves with some sources estimating a crash rate that is three times the crash rate of tangent sections. Curve related crashes involve a number of roadway and driver causative factors. Driver errors on horizontal curves are often due to the inappropriate selection of speed and the inability to maintain lane position. Factors that contribute to excessive speed include driver workload and distraction, fatigue, sight distance, misperception of degree of roadway curvature, and situational complexity. As agencies attempt to improve safety they are often looking for low cost measures that can be quickly and economically applied. Several low cost treatments such as use of post mounted delineators; on-pavement curve warning signs, raised pavement markings, wider edgelines, etc have been used to provide additional delineation around curves. A number of treatments have been applied but their effectiveness in improving safety on curves is not well understood. These paper discuses results of a study to evaluate strategies to reduce speed and crashes on curves. One strategy, adding reflectorized material to the posts of existing chevrons to provide additional curve delineation, was evaluated at two high crashes on rural 2-lane paved roadways in Iowa. Speed data were collected before and 1-month after installation of the treatments. Results suggest that the treatments were effective in reducing vehicle speeds at the center of the curve. Results for evaluation of speeds at the points of curvature were mixed. Overall, the treatment shows promise and offers a very low cost alternative for agencies.

Red light running (RLR) is a problem in the United States (US) that has resulted in 165,000 injuries and 907 fatalities annually. In Iowa, RLR-related crashes make up 24.5 percent of all crashes and account for 31.7 percent of fatal and major injury crashes at signalized intersections. RLR crashes are a safety concern due to the increased likelihood of injury compared to other types of crashes. One tool used to combat red light running is automated enforcement in the form of RLR cameras. Automated enforcement, while effective, is often controversial. Cedar Rapids, Iowa installed RLR and speeding cameras at seven intersections across the city. The intersections were chosen based on crash rates and whether cameras could feasibly be placed at the intersection approaches. The cameras were placed starting in February 2010 with the last one becoming operational in December 2010. An analysis of the effect of the cameras on safety at these intersections was determined prudent in helping to justify the installation and effectiveness of the cameras. The objective of this research was to assess the safety effectiveness of the RLR program that has been implemented in Cedar Rapids. This was accomplished by analyzing data to determine changes in the following metrics: (1) Reductions in red light violation rates based on overall changes, time of day changes, and changes by lane; (2) Effectiveness of the cameras over time; (3) Time in which those running the red light enter the intersection; and (4) Changes in the average headway between vehicles entering the intersection

The object of this research was to use naturalistic driving study data (NDS) to determine where drivers begin reacting to the presence of a curve. Understanding where drivers begin to react to the curve is important for optimal placement of traffic control devices, such as advance curve warning signs, as well as other countermeasures. Time series data were modeled using regression analysis. Results indicate that, depending on radius of curve, drivers begin reacting to the curve 164 to 180 meters (538.1 to 590.6 feet) upstream of the point of curvature. This was compared against sign placement guidelines in the 2009 Manual on Uniform Traffic Control Devices, and it was determined these guidelines are appropriately set based on where drivers actually react to the curve. The analysis found that drivers begin reacting to the curve sooner for curves with larger radii than for curves with smaller radii. Drivers may not be able to gauge the sharpness of the curve, or sight distance issues may be a concern for sharper curves. It should be noted that the model only identified where drivers reacted to the curve. This research question did not attempt to answer whether the reaction point was sufficient for drivers to successfully negotiate the curve. It is also noted that sample sizes are small. Due to resource and data constraints it was not possible to model a large number of drivers over large variation of different curve types. Consequently, the results provide useful information but should be used within the context of the study limitations.

This study documents the speed reduction impacts of two dynamic, electronic school zone speed limit signs at United Community Schools between Ames and Boone, Iowa. The school facility is situated along US Highway 30, a rural four-lane divided expressway. Due to concerns about high speeds in the area, the Iowa Department of Transportation (DOT) decided to replace the original static school zone speed limit signs, which had flashing beacons during school start and dismissal times (Figure 1), with electronic speed signs that only display the reduced school speed limit of 55 mph during school arrival and dismissal times (Figure 2). The Center for Transportation Research and Education (CTRE) at Iowa State University (ISU) conducted a speed evaluation study one week before and 1 month, 7 months, and 14 or 15 months after the new signs were installed. Overall, the new dynamic school zone speed limit signs were more effective in reducing speeds than the original static signs with flashing beacons in the 1 month after period. During the 7 and 14 month after period, speeds increased slightly for the eastbound direction of traffic. However, the increases were consistent with overall speed increases that occurred independent of the signs. The dynamic, electronic signs were effective for the westbound direction of traffic for all time periods and for both start and dismissal times. Even though only modest changes in mean and 85th percentile speeds occurred, with the speed decreases, the number of vehicles exceeding the school speed limit decreased significantly, indicating the signs had a significant impact on high-end speeders.

Slow-moving vehicles are commonly found on the rural roads of Iowa. Common slow-moving vehicles in Iowa were analyzed as a part of this thesis which includes farm, construction, maintenance, and all-terrain vehicles as well as mopeds. Though slow-moving vehicle crashes represent a very small percentage of crashes in Iowa, the high speed differential of these vehicles and other traffic can result in higher severity crashes. It is important to determine the crash characteristics that tend to result in higher severity crashes and develop safety standards to help reduce those high severity crashes. This thesis analyzes the commonalities of laws across the nation pertaining to slow-moving vehicle safety. It also contains a 3-year analysis of crashes in Iowa involving slow-moving vehicles and a statistical modeling of farm vehicle crash severity to determine crash characteristics that make a crash more likely to result in a high or low crash severity. The SMV Emblem is the most common saf...