<rss version="2.0" xmlns:atom="https://www.w3.org/2005/Atom">
  <channel>
    <title>Research in Progress (RIP)</title>
    <link>https://rip.trb.org/</link>
    <atom:link href="https://rip.trb.org/Record/RSS?s=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" rel="self" type="application/rss+xml" />
    <description></description>
    <language>en-us</language>
    <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>
    <image>
      <title>Research in Progress (RIP)</title>
      <url>https://rip.trb.org/Images/PageHeader-wTitle-RIP.jpg</url>
      <link>https://rip.trb.org/</link>
    </image>
    <item>
      <title>Evaluating the Willingness to Pay for Managed Lanes (MLs)</title>
      <link>https://rip.trb.org/View/2563659</link>
      <description><![CDATA[This research project will investigate users’ willingness to pay to use managed lane (ML) facilities in light of the recent and rapidly shifting demographic trends and develop a better understanding on how recent mobility options, shifts in telework, online shopping adoption, and demographic and societal trends may have affected the preferences and choices toward using ML facilities.]]></description>
      <pubDate>Wed, 11 Jun 2025 13:19:33 GMT</pubDate>
      <guid>https://rip.trb.org/View/2563659</guid>
    </item>
    <item>
      <title>Lifecycle Economic and Energy Efficiency Benefits of Managed Lane Corridors in Metro Atlanta</title>
      <link>https://rip.trb.org/View/2508942</link>
      <description><![CDATA[This project will compare the lifecycle economic cost and energy use of the Northwest Corridor Express Lane facility to the alternative of expanding general-purpose lane capacity along the I-75/I-575 corridors. Lifecycle energy will include energy embedded in materials, construction, on-road vehicle operations, and ongoing maintenance.]]></description>
      <pubDate>Tue, 11 Feb 2025 16:13:39 GMT</pubDate>
      <guid>https://rip.trb.org/View/2508942</guid>
    </item>
    <item>
      <title>Identify Best Locations for New Flex-Route Projects Throughout the State of Michigan</title>
      <link>https://rip.trb.org/View/2122512</link>
      <description><![CDATA[Travel demand variation is one of the main sources of traffic congestion. Managed lane strategies are proposed as a
viable approach for addressing the traffic congestion issue. The US-23 Flex-Route construction project is an example
of a successful application for managing lanes in the state of Michigan. It is essential to study state-wide congestion
distribution to identify the best locations for assigning the highest priority project candidates for future flex-routes
or other managed lane strategies. Financing these projects at the same time might be financially challenging. This
proposed research will also investigate developing a viable project rollout strategy that would support increasing
the number of managed lanes, including temporary shoulder use, throughout the state.]]></description>
      <pubDate>Mon, 31 Jul 2023 11:43:06 GMT</pubDate>
      <guid>https://rip.trb.org/View/2122512</guid>
    </item>
    <item>
      <title>Human Factors Study to Understand Driver Behavior on Managed Lane Facilities</title>
      <link>https://rip.trb.org/View/2196875</link>
      <description><![CDATA[The main goal of this research is to conduct a human factors study to understand driver behavior in managed lane facilities. Specifically, this research focuses on the driver behavior pertaining to the safety performance of buffer separation versus pylons separation and buffer separation versus concrete barrier separation on managed lane facilities. The research findings will enable the Florida Department of Transportation (FDOT) and local agencies to make informed decisions on separation treatments between the managed and general-purpose lanes. The study results could also be leveraged across the U.S., where managed lanes are operational.]]></description>
      <pubDate>Thu, 15 Jun 2023 10:19:02 GMT</pubDate>
      <guid>https://rip.trb.org/View/2196875</guid>
    </item>
    <item>
      <title>Safety Performance of Part-Time Shoulder Use on Freeways</title>
      <link>https://rip.trb.org/View/2118346</link>
      <description><![CDATA["Safety Performance of Part-Time Shoulder Use on Freeways,” was to develop models and other quantitative tools for practitioners to evaluate safety performance of freeways with part-time shoulder use (PTSU) (including Bus on Shoulder (BOS)). The research is complete; it produced models that predict (1) the frequency of fatal-and-injury (FI) crashes and (2) the frequency of property damage only (PDO) crashes. These models were applied to assess the overall effect of PTSU on total and severe crash frequency. Models are available for basic freeway segments, entrance speed-change lanes, and exit speed-change lanes. A severity distribution function (SDF) also was developed to predict the distribution of FI crashes among different severity levels. Each model includes variables that describe the traffic demand characteristics, geometric elements, and PTSU operational features. 
 
This continuation request will support pilot testing of the PTSU models developed in Project 17-89 by state DOTs that operate such facilities with the goal of determining whether additional resources are needed to support wider-scale implementation through HSM2. The pilot tests will provide material for one or more case studies that will help practitioners use the research products. In addition, review of the pilot states’ efforts will help identify any Highway Safety Manual (HSM)-related needs, such as text to be included with the models, text for other sections of the HSM to explain the relationship to other models, training materials, etc. Subject to the availability of data, the participating state DOTs will run the models to: (1) estimate FI and PDO crash frequencies, compare them to DOT experience, and evaluate whether the models are suitable in their present form for incorporation in HSM2; (2) evaluate differences in safety performance between right- and left-side PTSU; and (3) conduct a before-after study of freeways where PTSU was implemented during NCHRP Project 17-89.]]></description>
      <pubDate>Mon, 13 Feb 2023 15:34:52 GMT</pubDate>
      <guid>https://rip.trb.org/View/2118346</guid>
    </item>
    <item>
      <title>Dedicating Lanes for Priority or Exclusive Use by CVs and AVs</title>
      <link>https://rip.trb.org/View/1877223</link>
      <description><![CDATA[Converting existing general-purpose highway lanes to more restrictive access for use only by certain vehicles or travelers has been politically unacceptable ever since the disastrous initial attempt to convert a lane of the Santa Monica Freeway to HOV-only use 40 years ago. Because CV and AV systems can work much more effectively and provide much higher lane capacity when the equipped vehicles are clustered in close proximity to each other in the same lane, these technologies provide new motivations to convert lanes from general use to more specialized uses. The issue of dedicated lanes needs to be restudied now in light of these developments, to develop more authoritative estimates of the benefits that could be gained and of the disadvantages to the general purpose road users who would be excluded from those lanes.  The objective of this research was to develop guidance on the conditions that appear to be amenable to dedicating lanes for CV/AV users and what policy actions are needed to make this feasible. The research describes benefits to CV/AV users in the dedicated lanes and possible dis-benefits to non-users as a function of market penetration .]]></description>
      <pubDate>Thu, 09 Sep 2021 10:11:35 GMT</pubDate>
      <guid>https://rip.trb.org/View/1877223</guid>
    </item>
    <item>
      <title>Consumer Response to Road Pricing: Macro and Micro Modeling Tools for Socioeconomic Evaluation and Pricing of Managed Lanes</title>
      <link>https://rip.trb.org/View/1474431</link>
      <description><![CDATA[This study of the metropolitan Atlanta I-85 Express Lanes employs trip characteristics, facility operating conditions, and household demographics to provide a comprehensive overview of Express Lane users and their decision-making processes. The results are used to create a socioeconomic impact assessment tool at the macroscopic level and, at the microscopic level, a demand-modeling tool that can examine the response of consumers to different toll levels as a function of facility operating conditions and user demographics for forthcoming Express Lane implementations. The resulting applications will use the abundant data generated by the Express Lanes to impact current and future decision making.]]></description>
      <pubDate>Fri, 14 Jul 2017 13:10:05 GMT</pubDate>
      <guid>https://rip.trb.org/View/1474431</guid>
    </item>
    <item>
      <title>Behavioral Study for Managed Lane Pricing with Refund Option</title>
      <link>https://rip.trb.org/View/1367909</link>
      <description><![CDATA[The proposed study is a component of the principal investigator's (PI's) ongoing research effort to explore innovative pricing strategies for priced managed lanes (MLs).  The objective of this project is to investigate travelers' reactions to a possible refund option of priced MLs.  The investigation will focus on (1) gauging general interest and concerns regarding this concept, (2) eliciting travelers' choices of managed lane usage and refund claims under various situations, and (3) identifying and evaluating potential models to describe such choice behaviors. A stated preference (SP) survey will be developed and deployed in this project to collect relevant data.  Simple descriptive analysis will first be performed to gain insights to the dataset.  Choice behavior models in various fields and domains, including transportation, economics, insurance, and retail marketing, will be explored.  Model fitting will be performed on selected models. The type of this project is basic research.  It investigates a plausible future scenario where a refund option is provided to managed lane (ML) users.  In the past four years, the number of priced ML facilities in the U.S. have rapidly increased from 6 to 17.  However, refund option is not currently in practice.  The goal of this research is to address the challenge of developing innovative pricing strategies to support ML goals that range from operational efficiency to social benefits and public acceptance. Expected direct outcomes of this project include (1) a well-designed survey, (2) a rich dataset, (3) a comprehensive survey of choice models across various fields and domains, and (4) a set of fitted models for priced MLs with refund option.]]></description>
      <pubDate>Thu, 03 Sep 2015 01:00:34 GMT</pubDate>
      <guid>https://rip.trb.org/View/1367909</guid>
    </item>
    <item>
      <title>Integrating Meso- and Micro- Simulation Models to Evaluate Traffic Management Strategies</title>
      <link>https://rip.trb.org/View/1363809</link>
      <description><![CDATA[Currently, traffic management strategies such as adaptive control and ramp metering systems go though the following steps: (i) conceptualization of strategies, (ii) development of logic and software algorithms, (iii) simulation-based testing of the strategies, (iv) hardware implementation, (v) field testing of hardware/software systems, (vi) operational testing of the proposed systems, (vii) implementation and evaluation of the system. The simulation testing done in step (iii), when performed, is conducted using models based in one of the several of-the-shelf-simulation packages such as VISSIM, CORSIM, AIMSUN etc. Such models and simulation testing have been quite successful for isolated intersections and single intersections, and small networks with 1-3 intersections - where the effect of re-routing due to incidents, major events that result in changes in traffic patterns have none or only simple impacts on the simulations. Meso-models that simulate small to large networks, on the other hand, are used mostly at a planning level to evaluate long-term impacts of network wide transportation decisions and management strategies such as network changes (e.g. adding a lane), managed lanes, congestion pricing, dynamic messages, etc. Simulation based "Dynamic Traffic Assignment" (DTA) are typical of such models - where planners input traffic demand in terms of time-dependent Origin-Destination travel demands, and the models outputs traffic conditions, usually at the time resolution of hourly traffic conditions each day of the week. Some simulation based DTA models are being used in USA and elsewhere. It should be noted that meso simulation is really a spatial-temporal approximation of micro-simulation traffic - time steps in meso is in terms of 6 seconds, or 10 seconds, or in minutes whereas in micro they are in seconds or tenths of seconds; spatial resolution is in terms of roads segments and tenths of miles in meso whereas in micro one refers to vehicles in lanes and spaces in fractions of feet. The integration of micro-and macro- models has been attempted before, but the integration is not as seamless as it should be. Results of a macro model are sent "down" to the micro-model to provide travel demand, usually in a straightforward manner, but the results of the micro-model are not easily sent "up" to the macro model. Still this is very much needed, especially in the testing of Dynamic Mobility Applications (DMA) that are envisioned due to connected vehicle technologies, and Active Traffic and Demand Management (ATDM) strategies, multiple resolution in space and time is required. This project will consider two such applications: Proactive Multimodal Traffic Signal Control (PMTSC1) and Multimodal Adaptive Ramp Metering (MARM*). The signal control algorithms require data with time and space resolution of feet and seconds and while the optimization objectives require the prediction of traffic through the intersections over several minutes and even over hours. As with PMTSC, MARM algorithms require data with time and space resolution of feet and seconds and while the optimization objectives require the prediction of traffic through the ramps over several minutes and hours. Note that in both PMTSC and MARM, algorithms require prediction of the network conditions and the feedback of the conditions from the controls being developed.]]></description>
      <pubDate>Tue, 04 Aug 2015 01:00:28 GMT</pubDate>
      <guid>https://rip.trb.org/View/1363809</guid>
    </item>
    <item>
      <title>Proposed Practices for the Application of Dynamic Lane Use Control</title>
      <link>https://rip.trb.org/View/1359251</link>
      <description><![CDATA[The objective of this research was to develop recommendations for the application of dynamic lane use control based upon their human factors implications. This research discovered how dynamic lane use control should be interpreted broadly so as to include applications such as reversible lanes, hard shoulder running, dynamic junction control, and toll plazas.
]]></description>
      <pubDate>Sat, 27 Jun 2015 01:00:51 GMT</pubDate>
      <guid>https://rip.trb.org/View/1359251</guid>
    </item>
    <item>
      <title>High Occupancy Vehicle (HOV) / Managed Use Lane (MUL)</title>
      <link>https://rip.trb.org/View/1358878</link>
      <description><![CDATA[This project is being created to convert Pooled Fund Project TPF-5(029) to the “New” Pooled Fund Procedures. All new Funding Commitments will need to be made on the Pooled Fund Website to this new project and all new funds will be transferred to the Lead State/Agency by the partners. The Lead State/Agency will have the responsibility for Receiving, Obligating, Expending, and Balancing the funding for this project. The High Occupancy Vehicle (HOV)/ Managed Use Lane (MUL) Pooled Fund Study (PFS) is intended to serve as a forum and provide an opportunity for the participants to identify, address and collectively take on the key issues and challenges that are common among public agencies that are responsible for managing and operating HOV facilities. The HOV/MUL PFS focuses on the critical program, policy, technical, and other issues that arise throughout the life cycle of an HOV/HOT/MUL facility. The HOV/MUL PFS also provides an opportunity to facilitate the interaction, sharing of information, and successful practices with a broader audience to advance and improve upon the current state-of-the-practice related to the management, operation, and performance of HOV/HOT/MUL facilities. OBJECTIVES: The goal of this study is to assemble regional, State, and local agencies, service providers, and FHWA to: (1) identify issues that are common among agencies that manage roadway lanes as a tool to reduce congestion and optimize facility usage; (2) suggest projects and initiatives to advance practice; (3) select and initiate projects intended to address identified issues; (4) identify recommendations and potential solutions, and (5) disseminate results.
]]></description>
      <pubDate>Wed, 24 Jun 2015 01:01:13 GMT</pubDate>
      <guid>https://rip.trb.org/View/1358878</guid>
    </item>
    <item>
      <title>Research for the AASHTO Standing Committee on Planning. Task 52. Changes in Travel Behavior/Demand Due to Managed Lanes (HOV, HOT) Facility System Expansion</title>
      <link>https://rip.trb.org/View/1346903</link>
      <description><![CDATA[Understanding what happens to travel behavior when managed-lanes are implemented or expanded has been a challenge faced by state departments of transportation (DOTs) during highway corridor and systems planning. Current modeling and state of the practice do not fully capture the extent to which high occupancy vehicle (HOV) facility expansion changes travel behavior/demand on the managed lanes and on the general purpose lanes and do not delineate the resulting impacts on mode splits, travel times, and travel patterns. Given the availability of data, a nationwide analysis of travel behavior at locations where HOV and other managed lanes have been built or expanded would give planners a better idea of the range of travel behavior/demand changes that can be expected. Research into this topic would also support future research on high occupancy toll (HOT) lanes and Bus Rapid Transit (BRT).  The objective of this study is to evaluate and describe how expanding HOV or HOT facilities and other managed lane approaches (as distinct from services) influence corridor mode choice, travel times, and patterns. The results of this study will support better evaluation of needs and demand during highway system planning and corridor alternatives analysis. The research will be accomplished by the following tasks: (1) Performing a literature search to identify documented research on changes to travel behavior when managed lanes are implemented or expanded. (2) Determining which states and metropolitan areas have established new or expanded HOV, HOT, or other managed lanes. (3) Interviewing officials in each area that has added managed lane capacity, gathering studies that have been done, and obtaining any available data on travel behavior changes. (4) Identifying up to five case study locations to examine travel behavior changes due to managed lanes. Data may include that available through special studies, ITS monitoring systems, and other sources. (5) Conducting case studies and summarizing their results and the findings derived from each. (6) Completing final report outlining findings, conclusions, currently available approaches for analyzing managed lane impacts on travel behavior, and recommending future research needs.]]></description>
      <pubDate>Thu, 19 Mar 2015 01:01:41 GMT</pubDate>
      <guid>https://rip.trb.org/View/1346903</guid>
    </item>
    <item>
      <title>Impacts of TDM on Managed Lane Toll Prices</title>
      <link>https://rip.trb.org/View/1290916</link>
      <description><![CDATA[The purpose of this research is to quantify the extent to which transit and ridesharing reduce traffic density and lower tolls on the l-95 Express Lanes. The tolls on the l-95 Express Lanes are variable and are based on traffic density. Therefore, transportation strategies that increase person throughput can contribute to lower tolls. improved traffic flow and lower tolls both benefit the traveling public. This research benefits the state because dynamically priced managed lanes feature prominently in the state's future transportation plans, particularly in South Florida. This research will add to the body of research done already on the l-95 Express Lanes. lt will help the Florida Department of Transportation have a better understanding of the positive role played by transit and ridesharing in relation to dynamically priced managed lanes.]]></description>
      <pubDate>Sat, 08 Feb 2014 01:00:40 GMT</pubDate>
      <guid>https://rip.trb.org/View/1290916</guid>
    </item>
    <item>
      <title>Comparative Analysis of Dynamic Pricing Strategies for Managed Lanes (2012-089)</title>
      <link>https://rip.trb.org/View/1243168</link>
      <description><![CDATA[The pricing strategies on managed lanes (ML) are inspired by the congestion-pricing concept borrowed from the economics literature.  This concept has been thoroughly adapted to the case of traffic flow for static user optimum and system optimum.  However, little has been done in the dynamic case, where travel time delays due to congestion may change rapidly.  For example, we know that the marginal cost of an alternative is a decreasing function of time and that pricing according to marginal cost does not lead to minimum system cost.  These results have not been transferred to practice, which is unfortunate because existing real-time pricing strategies based on the static assumption will not lead to the desired result and in some cases (as our initial result suggests) may lead to significantly worse system performance compared to time-of-day pricing. The objective of this research is to investigate the performance of different dynamic pricing strategies for ML facilities.  The focus will be on the dynamic equilibria resulting from each pricing strategy and the benefits and costs thereof.  The problem will be analyzed from three perspectives: the tolling authority, the users, and society.  The following pricing strategies will be analyzed: i) time-of-day pricing based on historical traffic data, ii) real-time pricing based on traffic conditions on the ML, iii) real-time pricing based on traffic conditions on the ML and general-purpose lanes, iv) real-time pricing based on travel-time prediction uncertainty, and v) a combination of these.]]></description>
      <pubDate>Wed, 06 Feb 2013 01:00:20 GMT</pubDate>
      <guid>https://rip.trb.org/View/1243168</guid>
    </item>
    <item>
      <title>Departure Time Choice Model in the Presence of Time-of-Day Toll Pricing</title>
      <link>https://rip.trb.org/View/1231919</link>
      <description><![CDATA[Express Toll Lanes (ETL) initiative is Maryland's statewide initiative aimed to provide cost-effective way for congestion management including toll pricing and managed lanes. As a consequence, this initiative is expected to implement toll pricing on major Maryland's corridor including the Intercounty Connector (ICC), the capital beltway (I-495), and the I-95. One of the pricing schemes considered by the initiative is the time-of-day toll pricing scheme where toll price is adjusted in correspondence to the time of day or on the basis of the traffic conditions. This pricing scheme is gaining attention as a travel demand management strategy by providing incentive to travelers with more flexible departure time to travel during off peak period, thereby shifting peak travel demand. Meanwhile, travel demand model that forecasts the time when trips are taken need to be developed. Modeling departure time is essential for policy makers evaluating travel demand management alternatives, such as time-of-day toll pricing. Different toll prices by time of day induce traveler to perceive departure time choice similar to the mode choice selection. This modeling framework is challenging for analysts. First, the choice of departure time has to be identified or approximated either by simulation or by means of stated preference survey. Next, the interdependency of departure time choice and mode choice has to be carefully examined. The traditional approaches dealing with time of day estimate time of day factors (TODF) from observed data and assume that the same behavior will pertain in the future; this technique is used to estimate traffic volume by time period using the TODF. The newer methodologies such as "Peak Spreading" improve the limitation of TODF approach by accounting for the excess demand in certain corridors during the peak period and allow for more realistic assessment of travel condition in the future. However, peak spreading approach has relatively weak behavioral foundation and cannot fully address travel response to system changes; for instance, it cannot be used to fully analyze policy changes or the effects of travel demand management actions. The departure time choice, on the other hand enable analyst to assess the extent to which travelers respond to congestion at disaggregate level. Despite the widespread interest in the concept of departure time choice, there is very little empirical study on the impact of departure time choice in the presence of time-of-day toll pricing (especially in Maryland). This project proposes an empirical study that integrates the joint effects of departure time and mode choice. We will consider variables affecting departure time such as travel time, travel cost, travel time reliability and activity duration. The presence of time-of-day toll pricing will be taken into account in the model estimation process to develop a model that represents behavioral responses to pricing. Possible response of traveler to pricing in term of mode shift and departure time shift will be carefully examined. The extent to which the model could aid local agencies to achieve several objectives including toll revenue, system performance, and environmental impact will be examined.]]></description>
      <pubDate>Thu, 03 Jan 2013 14:28:36 GMT</pubDate>
      <guid>https://rip.trb.org/View/1231919</guid>
    </item>
  </channel>
</rss>