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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>
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    <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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      <title>Industry Stakeholder Perspectives on the Adoption of Electric Bicycles in British Columbia</title>
      <link>https://trid.trb.org/View/1588764</link>
      <description><![CDATA[Electric-assist bicycles (e-bikes) are an emerging mode of transportation that offers a sustainable alternative to automobile use in urban areas. Past research on e-bike adoption has focused on user perspectives. Understanding other stakeholder perspectives is also essential to implementing effective e-bike policy. The objectives of this research are to identify alignments and misalignments in perspectives on e-bike adoption across industry stakeholders in British Columbia (BC), including e-bike retailers, manufacturers, cycling coalitions, and government agencies, and to provide recommendations for e-bike policy that account for those perspectives. An online survey was distributed to industry stakeholders to examine perceived barriers to adoption, expected impacts of adoption, and effects of policy on adoption. Questions about regulations discriminated between five e-bike types: pedal-assist, throttle-assist, scooter-style, electric recumbents, and enclosed electric recumbents. Results indicate strong agreement among industry stakeholders that scooter-style e-bikes require separate and additional regulation from other types of e-bikes and from existing regulation in BC. In contrast, there was misalignment in the expected mode shift resulting from e-bike adoption, with government agencies least optimistic about diversion of automobile trips. Industry stakeholders broadly agreed on the need for speed regulation and viewed higher speeds as one of the least important benefits of e-bikes, which contrasts with past research on user perspectives. Policy recommendations include reclassifying scooter-style e-bikes, rebate or tax programs to reduce e-bike costs, further research on optimal e-bike speed limits, and continued support for improvements in general cycling infrastructure (a top priority for industry and user stakeholders).]]></description>
      <pubDate>Tue, 09 Apr 2019 13:59:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/1588764</guid>
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      <title>Potential power setups, fuels and hull designs capable of satisfying future EEDI requirements</title>
      <link>https://trid.trb.org/View/1532379</link>
      <description><![CDATA[Maritime emission regulations set limits for SOₓ and NOₓ emissions for health and environmental reasons, and for CO₂, through the Energy Efficiency Design Index (EEDI), with the general aim of mitigating global warming. EEDI verification is performed at the vessel's design speed and design loads, under calm-water conditions. This, although calm seas are the exception in shipping, and that even with calm-water conditions, ships usually operate at lower speeds than their design speed. A major challenge, if greenhouse gases (GHG) reduction targets are to be met through the EEDI, will be to identify EEDI-compliant solutions that reduce energy consumption and GHG emissions under realistic operational conditions, from lying idle at berth in port to when full power is required in critical situations at sea. In view of all the above, the authors use the Aframax tanker class to illustrate how such an assessment can be performed, and to display the differences in costs and benefits of options, all of which meet the requirements of the EEDI.]]></description>
      <pubDate>Mon, 17 Sep 2018 10:32:12 GMT</pubDate>
      <guid>https://trid.trb.org/View/1532379</guid>
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      <title>Safety effects of dynamic speed limits on motorways</title>
      <link>https://trid.trb.org/View/1504998</link>
      <description><![CDATA[Dynamic speed limits (DSL) are limits that change according to real-time traffic, road or weather conditions. In DSL-schemes road users are typically informed of speed limit changes by electronic signs that are housed within gantries situated above lanes. Dynamic speed limit systems are increasingly applied worldwide, usually on motorways. One of the objectives of dynamic speed limits is to improve traffic safety through reductions in speed variations within and across lanes and between upstream and downstream flows. This paper shows the results of an empirical evaluation of the effects on traffic safety of a dynamic speed limit system on motorways in Flanders, Belgium. The evaluation was done by means of a before-after analysis of crashes, completed with a cost-benefit analysis. The results show that the number of injury crashes decreased significantly (-18%) after the introduction of the system. A separate analysis for serious and fatal injury crashes revealed a non-significant decrease of 6%. A distinction according to crash type showed an almost significant decrease of 20% in the number of rear-end crashes whereas the number of single-vehicle crashes decreased by 15% (ns). However, no effect was found for side crashes. In addition to the analysis of the effects, a cost-benefit analysis was applied. The costs of the implementation of these systems were compared with the benefits of crash prevention. The cost-benefit analyses of the crash effects showed a benefits-to-costs ratio of approximately 0.7, which means that the costs tend to exceed the benefits. Taking into account the important margins of uncertainty with respect to both costs and benefits, the authors have also explored how the net benefits are affected by some key assumptions. The general conclusion is that there is no convincing evidence that the costs of the system currently outweigh the expected benefits in terms of crash prevention.]]></description>
      <pubDate>Thu, 29 Mar 2018 09:31:37 GMT</pubDate>
      <guid>https://trid.trb.org/View/1504998</guid>
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      <title>Economic Analysis of Freeway Speed Limit Policy Alternatives</title>
      <link>https://trid.trb.org/View/1424750</link>
      <description><![CDATA[Recently, nationwide speed limit policy modifications have resulted in a general upward trend in many states, including Michigan. In Michigan legislation has been proposed to raise posted speed limits on limited access freeways for passenger vehicles and for trucks and buses. In response, research was performed to assess the economic impacts associated with speed limit policy alternatives under consideration. The economic assessment included estimation of the agency costs and user benefits and disbenefits for each proposed policy alternative, including those related to infrastructure modifications, fuel consumption, travel time, and fatal crash occurrence. Calculation of the benefit–cost ratios indicated several findings. First, scenarios that increased only the freeway truck and bus speed limit from 60 mph to 65 or 70 mph had favorable benefit–cost ratios (i.e., greater than 1) as long as diesel prices remained below approximately $3 per gallon and fatal crashes did not increase by more than one per year systemwide. However, implementation of the 75 or 80 mph maximum freeway speed limit for passenger vehicles (70 mph for trucks and buses) in general resulted in unfavorable benefit–cost ratios. The reasons in large part were the expected increase in fatal crash occurrence, coupled with substantial infrastructure costs associated with geometric modifications that ultimately would be necessary to achieve compliance with state and federal design speed requirements. Therefore, freeway speed limit increases should be considered only for segments that have low historical crash rates and where design speed compliance can be maintained in general without costly geometric upgrades.]]></description>
      <pubDate>Wed, 28 Sep 2016 15:13:12 GMT</pubDate>
      <guid>https://trid.trb.org/View/1424750</guid>
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    <item>
      <title>Economic Analysis of 65 mph Speed Limits on Rural Highways</title>
      <link>https://trid.trb.org/View/1394316</link>
      <description><![CDATA[Speed management has been a long-standing concern of transportation agencies. Recently, nationwide speed limit policy modifications have resulted in a general upward trend in many states. In Michigan, legislation was proposed to raise the maximum speed limits on state-owned, rural, nonfreeway highways from 55 to 65 mph. In response to this proposed speed limit policy change, research was performed to assess the associated economic impacts through the use of benefit–cost analysis. Several potential implementation scenarios of the proposed speed limit policy were investigated; these included a limited subset of roadways with favorable geometry and full statewide implementation. A primary research task was to estimate the costs for infrastructure upgrades necessary to achieve compliance with state and federal design speed requirements for the cohort of roadways included within each 65 mph implementation scenario. User benefits and disbenefits associated with the proposed speed limit increase also were estimated, which included reduced travel times, increased fuel consumption, and increased traffic crashes. Although the travel time savings were estimated to exceed the fuel consumption costs, the resulting benefit was far outweighed by crash-related disbenefits and agency infrastructure costs for roadways that required major geometric modifications (e.g., vertical or horizontal realignment). Consequently, an increase in the speed limit to 65 mph on rural, nonfreeway highways should be considered only if the critical geometric elements can maintain design speed compliance without major modification. However, even for roadways on which design speed compliance is maintained, careful, site-specific consideration must be given to the potential safety impacts, particularly with respect to fatal and injury crashes, which may result after the speed limit is increased.]]></description>
      <pubDate>Wed, 30 Mar 2016 09:47:39 GMT</pubDate>
      <guid>https://trid.trb.org/View/1394316</guid>
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    <item>
      <title>Economic Analysis of Speed Limit Policy Impacts</title>
      <link>https://trid.trb.org/View/1338181</link>
      <description><![CDATA[Speed management has been a longstanding concern of transportation agencies. Recently, nationwide speed limit policy modifications have resulted in a general upward trend in many states, including newly proposed legislation to raise the maximum speed limits on freeways and high speed rural non-freeways in Michigan. This legislation also proposed to eliminate the freeway differential speed limit between passenger vehicles and trucks/buses. Research was performed to assess the tangible economic impacts associated with the speed limit policy alternatives under consideration in Michigan. The economic assessment included systemwide estimation of the agency and user costs and benefits for each policy alternative, including those related to necessary infrastructure modifications, increased fuel consumption, reduced travel times, and fatal crashes. Calculation of the benefit/cost ratios indicated that none of the proposed speed limit increase scenarios present a favorable economic condition compared to the current policy. This was especially true for the proposed policy scenarios that involved an increase in the maximum speed limit, opposed to only increasing the truck/bus speed limits, due in large part to the substantial infrastructure costs associated with geometric modifications that will ultimately be necessary for compliance with state and federal design speed requirements. Such costs will be especially severe for non-freeways and select urban freeways in dense urban areas, which are currently posted at 55 mph. Consequently, speed limit increases on high speed roadways should only be considered for sections of roadway where design speed compliance is largely maintained after the increase to avoid costly geometric improvements.]]></description>
      <pubDate>Thu, 26 Feb 2015 09:49:44 GMT</pubDate>
      <guid>https://trid.trb.org/View/1338181</guid>
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    <item>
      <title>Road traffic noise: a discussion paper towards an NRMA policy</title>
      <link>https://trid.trb.org/View/1201046</link>
      <description><![CDATA[In recent years, the general community has become increasingly aware and concerned about the issue of road traffic noise.  Throughout Sydney, the subject of noise has been hotly debated.  The opening of the Hornsby Bypass on the Sydney - Newcastle Freeway and the inquiry into the proposed F2 Castlereagh Freeway in Sydney's northwest focused attention on road traffic noise. Noise affects individuals in a number of ways.  Loss of sleep, annoyance and hearing difficulties are major impacts from noise.  Studies have also shown that excessive noise levels affect the physiological and psychological health of people. Such impacts are long term: people do not become accustomed to noise. To ensure a healthy lifestyle, it is preferable to live in a quiet environment.  Yet the majority of the community also expects to drive on a comprehensive, safe, efficient and well-maintained road network. Such a network would also provide benefits to road-based public transport, as well as minimising transport costs. Although it is possible to attenuate noise levels to desirable limits on roads, the financial cost to the community would be extremely high.  Therefore, alternative cost-effective measures need to be considered. This discussion paper on road traffic noise raises a number of points of concern to the NRMA about this complex and controversial issue.  The NRMA wishes to adopt a noise policy which meets community expectations, is technically and economically achievable, and which guides us towards a healthy environment in which we can happily live and work.]]></description>
      <pubDate>Fri, 24 Aug 2012 17:30:52 GMT</pubDate>
      <guid>https://trid.trb.org/View/1201046</guid>
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    <item>
      <title>Costs and benefits of general speed limits (maximum and minimum speeds); report of the thirty-seventh Round Table on Transport Economics, held in Paris on 24th and 25th February, 1977</title>
      <link>https://trid.trb.org/View/1175915</link>
      <description><![CDATA[]]></description>
      <pubDate>Fri, 24 Aug 2012 00:48:36 GMT</pubDate>
      <guid>https://trid.trb.org/View/1175915</guid>
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    <item>
      <title>COUTS ET AVANTAGES DES LIMITATIONS GENERALES DE VITESSE</title>
      <link>https://trid.trb.org/View/1053336</link>
      <description><![CDATA[CETTE BROCHURE PRESENTE LE TEXTE DU RAPPORT DE LA TRENTE-SEPTIEME TABLE RONDE D'ECONOMIE DES TRANSPORTS QUI S'EST TENUE A PARIS LES 24 ET 25 FEVRIER 1977 A PARIS.  LES PRINCIPAUX POINTS TRAITES SONT LES SUIVANTS :- LE POUR ET LE CONTRE DES LIMITATIONS DE VITESSE GENERALISEES - DONNEES POUR UNE DUREE SCIENTIFIQUE DE LA RELATION SUPPOSEE ENTRE UNE LIMITATION DE VITESSE  GENERALISEE D'UNE PART, LA SECURITE ET L'AISANCE DU TRAFIC D'AUTRE PART.   - ANALYSE DES COUTS ET AVANTAGES DES LIMITATIONS DE VITESSE GENERALISEES.  UNE IMPORTANTE BIBLIOGRAPHIE TERMINE CE RAPPORT.]]></description>
      <pubDate>Sun, 21 Nov 2010 03:01:49 GMT</pubDate>
      <guid>https://trid.trb.org/View/1053336</guid>
    </item>
    <item>
      <title>When to invest in high-speed rail links and networks?</title>
      <link>https://trid.trb.org/View/926734</link>
      <description><![CDATA[High speed lines using conventional rail technology with purpose built new lines for some if not all of the route network are considered in this report. The motivation for the introduction of high speed rail is often due to the need for higher capacity and an improvement in journey time. The success of the Japanese high speed system, particularly in gaining market share from air, was undoubtedly a major factor inspiring European railways to follow the same path. Market share studies from France and Spain showed that much more traffic changed modes from air than from road transport. Methods of appraisal for high speed rail are discussed. The principal benefits are time savings, additional capacity, reduced externalities from othermodes, generated traffic and wider economic benefits. The biggest external benefits of high speed rail are considered likely to come where road or air are highly congested and and expansion on those modes difficult and expensive, including in terms of environmental costs. Case studies for the Madrid-Seville line are presented. Key parameters influencing the case for high speed rail include break even demand volumes and the cost of construction. The effects of extending a proposed high speed line London - Birmingham to Leeds and Newcastle via Edinburgh and Glasgow are discussed. If feasible, immediate construction of the whole line is considered the best option, although the London - Birmingham  section was justified in its own right. Pricing policy for the use of high speed track is discussed. In general, a high access charge limits the frequency of service offered below theoptimal level and thus limits the benefits of the high speed track.]]></description>
      <pubDate>Thu, 26 Aug 2010 08:44:15 GMT</pubDate>
      <guid>https://trid.trb.org/View/926734</guid>
    </item>
    <item>
      <title>Evaluation of Best Practices in Traffic Operations and Safety: Phase I: Flashing LED Stop Sign and Optical Speed Bars</title>
      <link>https://trid.trb.org/View/813569</link>
      <description><![CDATA[In a previous extensive review of overseas literature, researchers identified 42 traffic operations and safety technologies and practices that were not currently deployed in Virginia. These were evaluated for their potential application in Virginia, and 12 measures were determined to be good candidates for piloting. Two of the measures, a flashing light emitting diode (LED) stop sign and optical speed bars (two patterns) were installed at three locations in Virginia for before and after evaluations. The flashing LED stop sign was installed at a T-intersection in western Albemarle County, Virginia, where the number of crashes was higher than expected. The measures of effectiveness for the sign were average speed of drivers approaching the sign and compliance with the sign. Average speeds decreased significantly (statistically) after the sign was installed, but only by 1 to 3 mph. Speeds decreased more during the night than during the day. The results of the compliance study were inconclusive Optical speed bars were installed on the centerline and edge line on both approaches to a short section of two-lane roadway in Fairfax County, Virginia. The section of roadway is hazardous, as it has inadequate vertical and horizontal alignment, narrow lanes, and reduced shoulders. A number of crashes had occurred on the section over the years, including a recent fatality. Average speeds both decreased and increased after installation, and the decreases were statistically significant right before and in the middle of the section. The decreases ranged from 1 to 3 mph. Optical speed bars were also installed across lanes on a major, four-lane undivided highway, at two approaches to a reduced speed limit zone in the town of Zuni, Virginia. Average speeds both decreased and increased after installation. The decreases were statistically significant at the beginning of the 45 mph speed zone on each end of town. The decreases ranged from 3 to 10 mph. Given the general positive results of the installations, the report recommends that flashing LED stop signs and optical speed bars be considered as safety countermeasures at appropriate locations where the numbers of crashes or crash rates are higher than expected or where excessive speeding occurs. A costs and benefits assessment indicated that, generally, the benefits in terms of reduced crashes exceeded the costs of the installed measures if only one crash was prevented.]]></description>
      <pubDate>Mon, 27 Aug 2007 16:43:12 GMT</pubDate>
      <guid>https://trid.trb.org/View/813569</guid>
    </item>
    <item>
      <title>Potential benefits and costs of speed changes on rural roads</title>
      <link>https://trid.trb.org/View/771061</link>
      <description><![CDATA[This paper was previously published in: Australian Transport Safety Bureau (ATSB), Report CR 216, and for the abstract see ITRD E210279.]]></description>
      <pubDate>Thu, 22 Dec 2005 14:49:50 GMT</pubDate>
      <guid>https://trid.trb.org/View/771061</guid>
    </item>
    <item>
      <title>POLITICAL SUPPORT FOR INTELLIGENT SPEED ADAPTATION (ISA): INTERVIEW STUDY AMONG REPRESENTATIVES OF NETHERLANDS POLITICAL PARTIES</title>
      <link>https://trid.trb.org/View/742965</link>
      <description><![CDATA[Many road safety experts regard Intelligent Speed Adaptation (ISA) as a powerful instrument for regulating safe driving speeds and achieving more safety. With regard to national Dutch politics, no clear course has yet been set out as to the introduction of a type of ISA as a road safety measure. This brings us to the question of how politicians view ISA. This report gives an account of a study into the political support for an 'ISA measure', by means of interviews with representatives of political parties (members of parliament and policy workers). The questions were divided into two aspects: (1) What is the political support for ISA at this moment; and (2) what do politicians take into account when determining their position about ISA? Two rounds of interviews were held. The first round took place with experts, and its purpose was to compile a knowledge file on ISA that was later put before a number of political representatives. The second round of interviews was meant to explore the political support and was aimed at representatives of political parties. They took place with parliamentarians from seven of the nine parties in the lower house. In spite of a broad political interest in an 'ISA measure', the interviewed politicians also had clear reservations. These reservations apply particularly to an obligatory introduction of ISA, and have to do with: a general limitation of personal freedom of choice of the motorist, the possible disturbances of the system's working because of its technical faults, fraud, and sabotage. It is not to be expected from the national political parties that political statements will be made to speed up ISA's introduction. There is, however, a positive attitude with regard to obtaining more information about the subject. Knowledge about costs and benefits of specific ISA variants, and concrete plans for ISA introduction in the Netherlands can be important incentives for a further political discussion about this subject. This report may be accessed by Internet users at: http://www.swov.nl/rapport/R-2004-05.pdf.]]></description>
      <pubDate>Wed, 03 Nov 2004 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/742965</guid>
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    <item>
      <title>POTENTIAL BENEFITS AND COSTS OF SPEED CHANGES ON RURAL ROADS</title>
      <link>https://trid.trb.org/View/684676</link>
      <description><![CDATA[The objective of the project was to explore the potential economic costs and benefits of changes to speed limits on rural roads in Australia. Net costs and benefits were estimated over a range of mean travel speeds (80 to 130 km/h) for rural freeways, other divided roads and undivided roads. Within the limits of the assumptions made and the data available for this study, the following general conclusions were reached: 1. Increasing the speed limit to 130 km/h for all vehicles on rural freeways would have substantial social costs. The total social cost could be constrained, and even reduced, if trucks were limited to 100 km/h on such roads. A variable speed limit system allowing speeds of 120 km/h for cars and light commercial vehicles during good conditions, but reduced to 100 km/h under adverse conditions, while limiting trucks to 100 km/h at all times, would keep total social costs below current levels. However, all scenarios whereby speed limits are increased for some vehicle types and circumstances are necessarily accompanied by increased road trauma to provide travel time saving benefits. 2. Increasing the speed limit to 130 km/h on rural divided roads would have even greater social costs than the increased limit on freeways. If trucks were limited to 100 km/h, the impact on total social costs would be smaller but they would still increase. Even a variable speed limit like that for freeways described above would be associated with an increase in road trauma costs. The higher crash rate on the divided roads compared with rural freeways will result in any speed limit increase producing even greater road trauma increases than on the freeways, despite lower traffic volumes on non-freeway roads. 3. If the 'willingness to pay' valuations of crash costs reflecting consumer preferences are used, the optimum speeds on rural freeways would be 120 km/h for cars and light commercial vehicles and 95 km/h for trucks. On divided rural roads, the optimum speeds would be 110 km/h and 90 km/h, respectively. If the speed limits on each of these rural roads were to be set at these optimum speeds for each vehicle type, there would be a reduction in total social costs in each environment. However, there would be increases in road trauma on the rural freeways due to the increase in car speeds. 4. There is no economic justification for increasing the speed limit on two-lane undivided rural roads, even on those safer roads with sealed shoulders. On undivided roads through terrain requiring slowing for sharp bends and occasional stops in towns, the increased fuel consumption and air pollution emissions associated with deceleration from and acceleration to high cruise speeds would add very substantially to the total social costs. Using 'human capital' costs to value road trauma, the optimum speed for cars is about the current speed limit (100 km/h) on straight sections of these roads, but 10-15 km/h less on the curvy roads with intersections and towns. The optimum speed for trucks is substantially below the current speed limit, and even lower on the curvy roads.]]></description>
      <pubDate>Fri, 12 Dec 2003 00:00:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/684676</guid>
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      <title>LOWERING EXISTING SPEED LIMITS ON ALL CLASSES OF ROADS: AN INCONTROVERTIBLE CASE</title>
      <link>https://trid.trb.org/View/501397</link>
      <description><![CDATA[This paper outlines earlier research by the author and his colleagues on the enforcement of speed limits and desirable levels for speed limits.  One conclusion was that the most cost-effective way of enforcing speed limits would be to equip vehicles with a manually operated switch on the dashboard, which the driver would set at the current speed limit.  When that limit was exceeded, an internal warning would alert the driver and a warning would be displayed outside.  A detailed cost-benefit analysis was also conducted to find optimal speed limits.  For each class of road in the UK, gains to drivers in terms of reduced journey times and other benefits are balanced against costs to other road users and society in general. Data were used from the Department of Transport speed surveys, value of travel time estimates, and accident costs.  The study concluded that UK speed limits should not exceed 55mph on motorways, 50mph on dual-carriageway trunk roads, 40mph on single-carriageway main roads, and 20mph on most urban roads.  The corresponding accident rates on such roads would be reduced to 55%, 55%, 80% and 30% of their present levels.  Speed control can delivery a wide range of public interest objectives very well; its potential as an immenseley powerful tool of transport policy is not yet realised and needs more publicity.  For the covering abstract see IRRD E100685.]]></description>
      <pubDate>Fri, 28 May 1999 00:00:00 GMT</pubDate>
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