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    <title>Transport Research International Documentation (TRID)</title>
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    <copyright>Copyright © 2026. National Academy of Sciences. All rights reserved.</copyright>
    <docs>http://blogs.law.harvard.edu/tech/rss</docs>
    <managingEditor>tris-trb@nas.edu (Bill McLeod)</managingEditor>
    <webMaster>tris-trb@nas.edu (Bill McLeod)</webMaster>
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      <title>Transport Research International Documentation (TRID)</title>
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    <item>
      <title>Traffic Management During Freeway Reconstruction and in Rural Work Zones</title>
      <link>https://trid.trb.org/View/2556674</link>
      <description><![CDATA[This report summarizes the results of studies conducted in Texas to evaluate traffic control and safety at various types of work zones. Based on the study findings, recommendations for improving work zone traffic management, particularly at rural work zones and at freeway reconstruction sites, were made and are summarized herein. The following topic areas are specifically addressed: 1. Work zone accidents, 2. Rural work zones, 3. Freeway reconstruction work zones, 4. Highway Advisory Radio, and 5. Work zone safety programs. This report is the final report in a series of seven which document the work conducted in Study 263.]]></description>
      <pubDate>Sat, 05 Jul 2025 17:02:50 GMT</pubDate>
      <guid>https://trid.trb.org/View/2556674</guid>
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      <title>Fiscal Year 2012/13 Highway Safety Improvement Program Annual Report</title>
      <link>https://trid.trb.org/View/1736653</link>
      <description><![CDATA[Moving Ahead for Progress in the 21st Century Act or “MAP–21” (Pub. L. 112–141, 126 Stat. 405) was signed in to law July 6, 2012, and continued the Highway Safety Improvement Program (HSIP) as a core program under title 23 United States Code section 148 to reduce fatalities and injuries on all public roadways.  Title 23 United States Code section 148(h) requires each state to submit an annual report to the Federal Highway Administration (FHWA) regarding its HSIP implementation and effectiveness and title 23 Code of Federal Regulations sections 924.15(a)(1) and 924.15(a)(2) specify that the report be submitted no later than August 31 of each year.In accordance with title 23 Code of Federal Regulations sections 924.15(a)(1) and 924.15(a)(2), this annual report describes the progress being made to implement projects and the status of program evaluations for the HSIP as described in title 23 United States Code section 148, for railway-highway crossings, (  23 U .S .C . § 130(g)), and for high-risk rural roads (HR3) (23 U .S .C . § 148(g)).The California Department of Transportation’s (Caltrans’) Division of Traffic Operations provided information for this report for the State HSIP, the Division of Rail for the Railway-Highway At-Grade Crossings Program, and the Division of Local Assistance for the local HSIP and HR3 Program.]]></description>
      <pubDate>Thu, 24 Sep 2020 18:27:15 GMT</pubDate>
      <guid>https://trid.trb.org/View/1736653</guid>
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      <title>New Jersey Department of Transportation Policy on the Use and Operation of Highway Advisory Radio</title>
      <link>https://trid.trb.org/View/1490845</link>
      <description><![CDATA[This document contains the New Jersey Department of Transportation’s policy on the use and operation of highway advisory radio. The policy was prepared by the authors with input, recommendations, and review by the New Jersey Department of Transportation (NJDOT) Research Selection and Implementation Panel. The policy was approved by the NJDOT Director of Traffic Operations.]]></description>
      <pubDate>Tue, 19 Dec 2017 12:23:26 GMT</pubDate>
      <guid>https://trid.trb.org/View/1490845</guid>
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    <item>
      <title>Using Agency Surveys and Benefit–Cost Analysis to Evaluate Highway Advisory Radio as Regional Traveler Information and Communication Tool</title>
      <link>https://trid.trb.org/View/1437853</link>
      <description><![CDATA[Highway advisory radio (HAR) is an older traffic information source that is not typically used by most travelers. However, it is still valuable as a regional traveler information and communication tool, especially in emergencies. To understand the benefits of HAR to professional agencies, two online surveys were conducted with state department of transportation officials throughout the United States and with Florida emergency management departments. The 28 completed state department of transportation surveys indicated that HAR was a valuable regional communication tool to reach more travelers and provided more detailed information than other technologies. Florida emergency management professionals stated that HAR was useful as a redundant technology if the phone and Internet-based technologies that they used to provide emergency alerts failed. In addition to these surveys, a detailed benefit–cost analysis that used the results of customer surveys was performed on the HAR system of the Florida’s Turnpike Enterprise, which consisted of 16 HAR units throughout Florida. This analysis quantified the regional travel time benefits to passenger vehicle occupants and commercial truck drivers who diverted because of HAR congestion messages and compared these benefits with the capital and operational costs of the system. Assuming that 5% to 20% of HAR congestion messages cause diversion, the estimated range of the HAR benefit–cost ratio was 4.02 to 16.08. These benefits would be even greater if use of HAR in emergencies, fuel savings, and emissions reductions were considered.]]></description>
      <pubDate>Mon, 27 Feb 2017 17:12:02 GMT</pubDate>
      <guid>https://trid.trb.org/View/1437853</guid>
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    <item>
      <title>Evaluating the Impact and Usefulness of Highway Advisory Radio (HAR) and Citizens’ Band Radio Advisory Systems (CBRAS) in Providing Traveler Information and Improving the User Experience on the Florida Turnpike Enterprise’s Toll Road Network and the Florida Interstate Highway (FIH) System</title>
      <link>https://trid.trb.org/View/1401060</link>
      <description><![CDATA[This research designed and conducted state-of-the-art traveler information surveys, agency surveys, and a benefit-cost analysis to evaluate the existing highway advisory radio (HAR) and citizens’ band radio advisory systems (CBRAS) on the Florida Turnpike Enterprise (FTE) and Florida Department of Transportation (FDOT) roadways. Six surveys (four traveler surveys and two agency surveys) were designed and conducted using various implementation methods, including the novel approach of having students survey travelers at FTE service plazas and FDOT rest areas using iPads to store the responses in real time. These surveys indicated that HAR and CBRAS should be continued, but that awareness and usage of these systems are low. HAR can be especially beneficial during emergency situations, such as hurricane evacuations. The benefit-cost analysis also showed that the benefits of HAR (travel time savings to drivers who divert due to HAR congestion messages) outweigh the costs of HAR, even if only 10% of HAR messages cause diversion. Considering these results, it is recommended for FTE and FDOT to continue supporting HAR and CBRAS on their roadways. It is also recommended to promote these systems through various outlets to increase awareness of these systems. In the future, it might be beneficial for FTE and FDOT to expand HAR and CBRAS throughout the state of Florida.]]></description>
      <pubDate>Mon, 21 Mar 2016 16:40:53 GMT</pubDate>
      <guid>https://trid.trb.org/View/1401060</guid>
    </item>
    <item>
      <title>Should Legacy Highway Advisory Radio and Citizens’ Band Radio Advisory Systems Be Continued? Analysis of Traveler Usage and Satisfaction Regarding These Systems</title>
      <link>https://trid.trb.org/View/1393925</link>
      <description><![CDATA[Advanced traveler information systems (ATIS) are important to provide travelers with accurate, up-to-date travel information. With the advent of new ATIS technologies, such as smartphone applications, roadway agencies need to understand how travelers use existing ATIS technologies, such as the legacy Highway Advisory Radio (HAR). The University of Central Florida implemented three traveler surveys and one truck driver survey to obtain the opinions of Florida roadway users regarding HAR, the Citizens’ Band Radio Advisory System (CBRAS), and other traffic information sources. Travelers typically preferred dynamic message signs (32%), smartphone applications (23%), and vehicle navigation devices (21%) for general traffic information. Some 57% of travelers were aware of HAR, and 42% of these travelers had used HAR, with 84% of users expressing satisfaction with HAR. Additionally, 87% of travelers said that they would use HAR during emergencies, such as hurricanes. A tree model targeting user satisfaction was developed; the model showed that HAR users who thought HAR should be continued, or who would use HAR in emergencies, as well as more frequent HAR users, were more likely to be satisfied. Only 12% of surveyed truck drivers had ever used CBRAS, but these users tended to utilize CBRAS frequently, and 92% indicated satisfaction with CBRAS. Truck drivers preferred vehicle navigation devices (28%) and smartphone applications (22%) to receive traffic information. Even though these surveys indicate that new technologies are more popular than HAR and CBRAS, these older systems satisfy users and should be kept for redundancy; cellular communications may fail during emergencies.]]></description>
      <pubDate>Mon, 21 Mar 2016 16:40:48 GMT</pubDate>
      <guid>https://trid.trb.org/View/1393925</guid>
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    <item>
      <title>Rocky Mountain National Park: 3 Years of ITS</title>
      <link>https://trid.trb.org/View/1337210</link>
      <description><![CDATA[In 2011, Rocky Mountain National Park, in collaboration with the Town of Estes Park, had its first experience with an intelligent transportation system primarily to address crowding in the 1) Bear Lake Road corridor within Rocky Mountain National Park and 2) Town of Estes Park. Rocky Mountain National Park and the Town of Estes Park continued to use intelligent transportation system components in 2012 and 2013; however during these years, in addition to addressing crowding, the system was intended to inform visitors of the construction within the Bear Lake Road corridor. Evaluations were performed each year to provide other practioners information on the effectiveness of ITS tools deployed in managing visitors through recreational areas. This paper discusses: a short history of intelligent transportation systems in national parks; characteristics of the intelligent transportation system deployments for Rocky Mountain National Park and the Town of Estes Park for 2011, 2012, and 2013; findings as a result of evaluations performed each year; and overall findings. Overall findings include 1) the most effective use of the dynamic message signs is on US 36, 2) the dynamic message signs have a significant impact on the use of the Fairgrounds Park-n-Ride, 3) static signage is an important last-link, 4) Fairgrounds Park-n-Ride users return in subsequent years, 5) the Fairground Park-n-Ride is capturing mostly day visitors, and 6) passive surveys were more effective at the Fairgrounds Park-n-Ride than at the Estes Park Visitor Center.]]></description>
      <pubDate>Thu, 26 Feb 2015 10:05:22 GMT</pubDate>
      <guid>https://trid.trb.org/View/1337210</guid>
    </item>
    <item>
      <title>HAR Best Practices and Future Direction</title>
      <link>https://trid.trb.org/View/1333221</link>
      <description><![CDATA[This document presents the complete findings of the ENTERPRISE Highway Advisory Radio (HAR) Best Practices and Future Directions project. The overall intent of this project is to provide ENTERPRISE member states with guidance to help them better understand how they should pursue HAR technologies and approaches in the future. To accomplish this, the project goals are defined as follows: Goal 1: To help members understand how HAR is being used by transportation agencies today; Goal 2: To help members understand the potential value of HAR; and Goal 3: To help members understand the current and potential future state of HAR technology practices. The document presents a general background of HAR, a summary of HAR uses and value, as well as the current and potential future state of HAR technology practices. Information for this project was gathered through literature reviews and interviews with transportation agencies operating HAR and manufacturers of HAR systems.]]></description>
      <pubDate>Tue, 23 Dec 2014 12:08:27 GMT</pubDate>
      <guid>https://trid.trb.org/View/1333221</guid>
    </item>
    <item>
      <title>Warrants for Intelligent Transportation System (ITS) Devices</title>
      <link>https://trid.trb.org/View/1333227</link>
      <description><![CDATA[In 2006, many ENTERPRISE member agencies were facing the challenge of increasing requests for the deployment of technology devices (commonly referred to as Intelligent Transportation Systems (ITS) devices). The group believed that a process of assessing whether individual devices are warranted at specific locations could help them in prioritizing device deployments. In 2009, the group developed initial warrants for the following Intelligent Transportation System (ITS) devices to assist agencies in the decision process of deploying technology devices as well as to validate the location of deployed devices: Closed Circuit Television (CCTV); Dynamic Message Signs (DMS); Highway Advisory Radio (HAR); and Road Weather Information Systems (RWIS). In 2010 warrants were developed for the following technology devices: Variable Speed Limit (VSL) Signs; Dynamic Speed Display Signs (DSDS); Curve Warning Systems; Ramp Meters; and Intelligent Work Zones. ENTERPRISE has continued to identify additional ITS devices for warrant development and in 2013 developed warrants for: Intersection Conflict Warning Systems (ICWS). This document represents the efforts performed to develop the device warrants. Section 8 of this report contains the text of each device warrant which is also included on the ITS Warrants website: http://enterprise.prog.org/itswarrants/.]]></description>
      <pubDate>Tue, 23 Dec 2014 12:08:20 GMT</pubDate>
      <guid>https://trid.trb.org/View/1333227</guid>
    </item>
    <item>
      <title>Traffic Incident Management State of the Art Review</title>
      <link>https://trid.trb.org/View/1132251</link>
      <description><![CDATA[Traffic incident management (TIM) is a critically important piece of every transportation network management program. It should be considered in all stages of developing and implementing a network management and operations program as a key to reducing congestion. TIM programs have existed for more than 20 years. For the purpose of this paper, the definition of traffic incident is “any non-recurring event that causes a reduction of roadway capacity or an abnormal increase in demand.” This definition will provide the necessary broadness for types of traffic incidents that are going to be addressed here and for the adjustment to new ways of defining traffic incidents. Activities related to incident management are one of the major responsibilities of traffic and transportation engineers. This report is focused on tools and strategies implemented in the area of Traffic Incident Management (TIM). Definitions and classifications of traffic incidents are presented at the beginning of the report. Stages in TIM are presented based on the most detailed approach in the available literature. Finally, this report explains the application of Variable Message Signs (VMSs), 511 Service, Highway Advisory Radio (HAR), and ramp metering in TIM process.]]></description>
      <pubDate>Wed, 29 Feb 2012 13:04:26 GMT</pubDate>
      <guid>https://trid.trb.org/View/1132251</guid>
    </item>
    <item>
      <title>Rocky Mountain National Park Dynamic Message Sign/Highway Advisory Radio Operations Plan</title>
      <link>https://trid.trb.org/View/1128240</link>
      <description><![CDATA[The purpose of this project is to deploy and test Dynamic Message Sign (DMS) and Highway Advisory Radio (HAR) technologies as an interim solution to the congestion issues in the Bear Lake Corridor of Rocky Mountain National Park (ROMO). Central Federal Lands Highway Division (CFLHD), working in collaboration with Rocky Mountain National Park, recommended pursuing an interim solution until the planning effort from the 2010 Paul S. Sarbanes Transit in Parks grant is completed. The goals of the interim Intelligent Transportation System (ITS) are to: shift visitors’ travel mode from private vehicles to shuttle buses; quantify the reductions in emissions pollution as a result of the mode shift; intercept visitors east of their arrival to the Town of Estes Park, spread the arrival of people and vehicles into ROMO using an “Insider’s Tip” on the HAR, improve the visitor experience through better dissemination of traveler information, collaborate with the Town of Estes Park, the Colorado Department of Transportation (CDOT), and CFLHD, introduce ROMO to ITS Systems, and select ITS devices easy to operate and maintain.]]></description>
      <pubDate>Thu, 16 Feb 2012 10:15:08 GMT</pubDate>
      <guid>https://trid.trb.org/View/1128240</guid>
    </item>
    <item>
      <title>Rocky Mountain National Park Intelligent Transportation System Evaluation Plan</title>
      <link>https://trid.trb.org/View/1122168</link>
      <description><![CDATA[Rocky Mountain National Park (ROMO) has maintained a consistent level of visitation over the last few years, approximately 3 million annual visitors. About 40% of these visitors come from the “front range,” which includes residents of Denver, Fort Collins, and their surrounding suburbs. Visitation is concentrated during the peak summer season, resulting in serious congestion in ROMO and its gateway community of Estes Park, Colorado. In an effort to reduce congestion and improve visitor experience, a pilot Intelligent Transportation System (ITS) composed of Dynamic Message Signs (DMS) and Highway Advisory Radio (HAR) will be implemented during the summer of 2011. This document presents a plan for evaluating the effectiveness of the ITS in achieving the project goals. The goals, objectives, performance measures and data sources are discussed, as well as the specific data collection needs defined for this evaluation. The final section describes how the data will be utilized in the analysis.]]></description>
      <pubDate>Fri, 04 Nov 2011 16:14:13 GMT</pubDate>
      <guid>https://trid.trb.org/View/1122168</guid>
    </item>
    <item>
      <title>Improved Chain Control Operations</title>
      <link>https://trid.trb.org/View/1116086</link>
      <description><![CDATA[California Department of Transportation field maintenance personnel use turntable signs to advise motorists of chain control conditions on rural highways. The operator turns on the sign on the shoulder and then walks across the freeway to turn on the matching sign on the median. Walking across highways can be hazardous, especially when done frequently and in bad weather. This Preliminary Investigation identifies safer and more efficient state practices and tools to alert travelers to winter weather conditions. Tools include traveler information systems, 511 systems, highway advisory radio systems, and changeable (variable/dynamic) message signs.]]></description>
      <pubDate>Fri, 23 Sep 2011 07:27:32 GMT</pubDate>
      <guid>https://trid.trb.org/View/1116086</guid>
    </item>
    <item>
      <title>Improving Highway Advisory Radio Predictability and Performance</title>
      <link>https://trid.trb.org/View/1116084</link>
      <description><![CDATA[Highway Advisory Radio (HAR) stations allow highway agencies to broadcast important messages about traffic, weather and roadway conditions. The California Department of Transportation (Caltrans) has deployed HAR stations across the state, but performance is often unpredictable, with signal strength often failing to meet the state’s intended design criteria. This Preliminary Investigation examines design factors related to radio wave propagation; topography; environmental characteristics (geology, ground conductivity); relevant system components and configurations (antennae, grounding); and related factors affecting HAR performance. Findings suggest that performance issues with HAR are common and HAR users and suppliers have developed approaches to optimize performance. System grounding and siting are important, but economics and topography are limiting factors.]]></description>
      <pubDate>Fri, 23 Sep 2011 07:27:32 GMT</pubDate>
      <guid>https://trid.trb.org/View/1116084</guid>
    </item>
    <item>
      <title>Greater Yellowstone Regional Traveler and Weather Information System: U.S. Highway 89 Project</title>
      <link>https://trid.trb.org/View/1108725</link>
      <description><![CDATA[The transportation network that serves Yellowstone National Park has some operational challenges, including changing weather conditions, alternate routes that are separated by great distances, and animal–vehicle conflicts. The purpose of this project was to develop, implement and evaluate a system to accurately provide necessary information to those who manage and utilize the transportation system along the U.S. Highway 89 corridor and other routes in and around the park. The project installed highway advisory radio (HAR) stations at four of the five entrances to the park, and purchased the following portable equipment used to provide enhanced traveler information within the park as well as on roadways leading to the park: four portable dynamic message signs, two portable dynamic message signs with HAR transmitters, and one portable HAR transmitter. Further, the park integrated its traveler information into the 511 traveler information phone systems operated by the Idaho, Montana and Wyoming Departments of Transportation to provide road condition and related information for travelers. In addition, through the project, fifteen National Weather Service receivers tied to low-powered AM transmitters were purchased. While not yet installed, these systems will serve as a low-cost alternative to a HAR system, and provide weather and traveler information in the park’s campgrounds. A survey of park visitors that was conducted to evaluate the traveler information systems indicated the implemented technologies provide useful traveler information to the public. The project demonstrated the value of using these advanced technologies to improve the distribution of traveler information. Finally, a pilot shuttle service was implemented to determine the use of alternative modes between the park and gateway communities. Ridership data indicate that such an alternative may be feasible.]]></description>
      <pubDate>Fri, 05 Aug 2011 16:09:27 GMT</pubDate>
      <guid>https://trid.trb.org/View/1108725</guid>
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