Evaluation of Alternatives to Provide Wet-Nighttime Delineation

The objective of this study was to compare the performance of various types of materials, devices, and procedures that can potentially delineate roadways during wet, nighttime conditions. Snowplowable markers provide the most effective wet-nighttime delineation. Durability issues associated with the steel casting marker make the recessed marker preferable over the life of the pavement. Wet reflective tape placed in a groove provided both dry and wet-nighttime delineation and remained durable. The performance of thermoplastic material installed on the pavement surface supports its future use but will not provide wet-nighttime delineation. Inconsistent performance of inlaid tape argues against its expanded use. Poor performance shows that future use of wet-reflective tape should not be considered. The research indicates an effective lane delineation procedure for four lane roads would include: recessed markers on lane lines (at 80-foot centers), grooved wet-reflective tape for lane lines, and spray thermoplastic for the edge lines. A cost analysis, considering durability of the materials, show that the cost of using more durable materials over the life of the pavement is not dramatically more than the cost of traffic paint. Edge line rumble stripes and centerline rumble strips enhance wet-nighttime delineation and should be incorporated into resurfacing projects on two-lane roads where pavement width permits

Toolbox of Countermeasures for Rural Two-Lane Curves [updated], TR-579, October 2013

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 their own research, through a survey of the literature, and through discussions with other professionals. Coverage of curve countermeasures in this toolbox is not necessarily comprehensive. For each countermeasure covered, this toolbox includes the following information: description, application, effectiveness, advantages, and disadvantages

Toolbox of Countermeasures for Rural Two-Lane Curves

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 their own research, through a survey of the literature, and through discussions with other professionals. Coverage of curve countermeasures in this toolbox is not necessarily comprehensive. For each countermeasure covered, this toolbox includes the following information: description, application, effectiveness, advantages, and disadvantages. Countermeasures covered are as follows: speed signs, chevrons, widening/adding paved shoulders, reflective barriers, high-friction treatments, raised pavement markers, edge lines, transverse pavement markings, vertical delineation, rumble strips, rumble stripes, on-pavement curve signing, flashing beacons, dynamic curve warning systems, and pavement inset lights

Assessing the visibility of raised pavement markers and alternative forms of delineation

Raised Pavement Markers (RPMs) are used by a number of transportation agencies with the objective of improving roadway safety, especially in complex roadway geometries and along wet roads. Because of maintenance and cost issues, many transportation agencies are exploring alternatives to RPMs such as wet reflective pavement tape and barrier-mounted reflective delineators. In order to assess the relative potential of these devices to contribute to nighttime driving safety, the luminances of new and used RPM samples from different manufacturers and having different colors and of several alternative delineation devices were measured in the laboratory using a range of geometric conditions relevant to the driving task. From these data, Luminances under representative low-beam headlight illumination were determined and these quantities were used to estimate driver visual performance. Large variations in luminance yielded relatively small differences in visual performance for a viewing distance of 100 m, primarily because of the plateau characteristic of visual performance. Differences in threshold visibility distances were greater, with distances at identification threshold for the devices measured ranging approximately from 150 to 400 m. Used RPMs had luminances 20…30% lower than new RPMs but similar visibility characteristics as new devices. The analysis method in this study may be useful for practitioners seeking to characterize the visual effectiveness of RPMs and other roadway delineation devices and systems

Evaluation of Raised Pavement Markers

Task Order 328In the State of New Jersey, raised pavement markers (RPMs) are used along all centerlines and skip lines, regardless of traffic volume, roadway geometry, or roadway classification. The extensive use of RPMs has raised interest in understanding 1) whether this significant investment generates variant safety benefits at different locations; 2) whether there are alternatives or modifications to the existing RPMs; and 3) how to optimize the installation, monitoring, and maintenance of RPMs and their promising alternatives in order to attain a more cost-effective safety improvement. This study reviewed the relevant literature and provided a methodological framework for quantifying the safety effectiveness and implementation costs of RPMs and their alternatives given specified road and traffic characteristics. A luminance measurement method was developed to allow researchers to estimate the luminance of these devices and to compare different reflective pavement markers and their alternatives regarding the ability to provide visual delineation. The study also analyzed the installation practices in various states and proposed guidelines for the use of RPMs and relevant alternatives accounting for various road classification, geometry, and traffic factors. Finally, the study developed a computer-aided decision support tool that can be used to calculate the life cycle cost of RPMs and other alternatives, thereby supporting decisions with respect to the optimal use of safety investment

Survey of Lane Delineation Methods

The objective of this study was to summarize the nationwide experience pertaining to various lane delineation methods. The usage, cost, and problems associated with each alternative could then be analyzed for the purpose of determining an optimum marking program. A survey of the methods of lane delineation used across the United States was done by means of a questionnaire sent to each state. Responses were received from 46 states. Most of the information dealt with the following lane delineation methods: raised pavement markers, pavement tape, thermoplastic markings, and paint and beads

Lane markings in night driving: a review of past research and of the present situation

One of the basic driver tasks is to follow the road. In daytime driving, when the visibility of the road in clear weather is unobstructed, this is normally not a problem. However, when driving at night on dark roads with low beams, it is often quite difficult to see the direction the road is taking. Indeed, drivers state that poor road guidance is their main problem in night driving. To overcome this problem, roads are fitted with retroreflective pavement markings, which are visible in night driving. This study was conducted to review the role, effects, and functioning of lane marking in night driving. The report consists of five sections. Section 1 details the scope and the limitations of this report. Section 2 presents a discussion of drivers’ needs for road guidance by means of pavement markers in general and lane markings in particular. Section 3 reviews the voluminous previous research on lane markings, focusing primarily on visibility and photometric characteristics of lane markings in night driving. Section 4 provides a summary of the issues related to lane markings. Section 5 presents the general conclusions and proposals for research topics and technical developments. The overall conclusion is that while drivers need both long-range guidance (a preview time of at least 5 s) and short-range guidance (a preview time of up to 3 s), present pavement markings often offer only short-range road guidance, especially in wet road conditions. Despite the extensive past research on pavement markings, many general and specific questions remain to be answered.Michigan University, Ann Arbor, Industry Affiliation Program for Human Factors in Transportation Safetyhttp://deepblue.lib.umich.edu/bitstream/2027.42/49387/1/UMTRI-98-50.pd

Installation and Maintenance of Raised Pavement Markers at State Transportation Agencies: Synthesis of Current Practices

Although raised pavement markers (RPMs) have been widely applied by the Indiana Department of Transportation (INDOT), there have been multiple cases where snowplowing activities have damaged pavements as well as the raised pavement markers on INDOT’s roadway assets. Dislodged raised pavement markers could reduce the design life of pavements because they leave openings for water and debris to infiltrate through pavement section. Interviews with INDOT personnel indicated that the proper installation of the markers and careful attention to the tooling of the center line of the concrete pavements could alleviate this problem. To explore issues related to the proper installation of RPMs, this study (INDOT/JTRP SPR 4318) was launched by the Indiana Department of Transportation (INDOT)/Joint Transportation Program (JTRP) to develop a synthesis of current practices on installation and maintenance of raised pavement markers at State Transportation Agencies (STAs) in the U.S. The study was conducted using a qualitative exploratory approach focusing on the review of current practices in installation and maintenance of raised pavement markers among STAs. Survey analysis and focused interviews with personnel from STAs, along with reviews of documents provided by STAs were the avenues used for data collection in this project