Roadway Sections Research Articles

Characterizing Pavement Surface Distress Conditions with Hyper-Spatial Resolution Natural Color Aerial Photography

Roadway pavement surface distress information is critical for effective pavement asset management, and subsequently, transportation management agencies at all levels (i.e., federal, state, and local) dedicate a large amount of time and money to routinely evaluate pavement surface distress conditions as the core of their asset management programs. However, currently adopted ground-based evaluation methods for pavement surface conditions have many disadvantages, like being time-consuming and expensive. Aircraft-based evaluation methods, although getting more attention, have not been used for any operational evaluation programs yet because the acquired images lack the spatial resolution to resolve finer scale pavement surface distresses. Hyper-spatial resolution natural color aerial photography (HSR-AP) provides a potential method for collecting pavement surface distress information that can supplement or substitute for currently adopted evaluation methods. Using roadway pavement sections located in the State of New Mexico as an example, this research explored the utility of aerial triangulation (AT) technique and HSR-AP acquired from a low-altitude and low-cost small-unmanned aircraft system (S-UAS), in this case a tethered helium weather balloon, to permit characterization of detailed pavement surface distress conditions. The Wilcoxon Signed Rank test, Mann-Whitney U test, and visual comparison were used to compare detailed pavement surface distress rates measured from HSR-AP derived products (orthophotos and digital surface models generated from AT) with reference distress rates manually collected on the ground using standard protocols. The results reveal that S-UAS based hyper-spatial resolution imaging and AT techniques can provide detailed and reliable primary observations suitable for characterizing detailed pavement surface distress conditions comparable to the ground-based manual measurement, which lays the foundation for the future application of HSR-AP for automated detection and assessment of detailed pavement surface distress conditions.

How eye movement and driving performance vary before, during, and after entering a long expressway tunnel: considering the differences of novice and experienced drivers under daytime and nighttime conditions.

IntroductionDriving environment in tunnels is quite different from the ordinary roadway sections, especially the entrance locations, which causes great difficulty in obtaining and interpreting information through fixations and saccades that are relevant to driving safety. Therefore, it is necessary to understand driver's visual behaviors while entering a tunnel so as to take the countermeasures for accident prevention.Case descriptionIn order to identify the variation of driver’s visual features during the process of tunnel entry, 18 participants were recruited to take part in a driving test conducted in real tunnel sections between Qipanguan toll and Jinshui toll of the G5 expressway in Shaanxi, China. During this test, the drivers’ fixations, saccades and driving performances were captured for further analysis.Discussion and evaluationThe test data revealed that the driver’s number of fixations, duration of fixations and number of saccades increased gradually at the transition zone. The number of fixations, duration of fixations and number of saccades then drop slightly until the end of the transition zone, and then rise just a little to a stable value after fully adapting to the driving conditions inside the tunnel. Meanwhile, the driver’s number of saccades and saccade amplitude value decreased first, and then increased gradually until reaching a relatively stable value inside the tunnel. Additionally, drivers are more cautious at the transition zone, driving conservatively at lower speed, while decreasing their steering wheel angle and minimizing the vehicle’s lateral deviation. Specially, novice drivers require a longer transition zone before tunnel entry compared to the experienced ones. Moreover, both novice and experienced drivers take more time to get prepared for tunnel entry while driving at night.ConclusionTunnel entrance section is far more dangerous, so drivers should be educated to get ready ahead for tunnel entry, drive cautiously at lower speed and pay full attention to the traffic flow conditions while driving through the tunnel, especially for the novice drivers in night tasks. Tunnel entrance is suggested to have easily identifiable frame design, with effective traffic signs placed at least 170 m before the entrance and gradually changeable LED lighting along the transition zone. All these suggestions provide insight into potential strategies for reducing and preventing traffic accidents and injuries at the tunnel locations.

Numerical Analysis of Low-Fill Box Culvert under Rigid Pavement Subjected to Static Traffic Loading

AbstractThis paper presents a numerical study on culverts under rigid pavements subjected to static traffic loading. The numerical study was based on the results of a comprehensive field study of a single-cell low-fill box culvert under three roadway sections (concrete pavement, concrete shoulder, and unsurfaced fill). The culvert in the field test was instrumented with displacement transducers and pressure cells to capture the deformations and pressures resulting from different combinations of wheel loads from a test truck pulling a low-boy trailer loaded with a backhoe. Deflections under the culvert roof and pressures on the culvert were measured during loading. Properties of soil and pavement layers were determined in the laboratory. A three-dimensional (3D) numerical model of the culvert was developed using a finite-difference program. The numerical model with material properties was verified with the field test results. A parametric study was conducted to investigate the influence of cement concrete ...

Traffic Kinematic Wave Propagationby Bituminous Asphaltic Concrete Road Distress

Traveling on bituminous asphaltic concrete roads plagued with potholes and edge subsidence is common in Nigeria and a better understanding of traffic dynamics has both theoretical and practical implications. In this study, we present continuous kinematic wave models of traffic flows at roadway section with and without bituminous asphaltic concrete distress. In particular, traffic kinematics was not treated as shockwave, rather as traffic dynamics that can trigger rarefaction or shockwave. In the paper the hypothesis that bituminous asphaltic concrete with significant distress will trigger traffic kinematic that may accentuate rarefaction or shockwave was investigated. Maximum flowrate polynomial estimation method based on extrapolation of the flows from flow and density curve was used. The method assumes that density at maximum flowrate is not affected by bituminous asphaltic concrete distress, which implies that traffic dynamics are fully the result of travel speed changes. Average traffic shockwave of about -20km/h were caused by bituminous asphaltic concrete with severe distress. Discussion and further studies are presented in the conclusion section.

The Complex Function Method Roadway Section Design of the Soft Coal Seam

As for the sophisticated advanced support technique of vertical wall semicircle arch roadway in the three-soft coal seam, a design of flat top U-shape roadway section was put forward. Based on the complex function method, the surrounding rock displacement and stress distribution laws both of vertical wall semicircle arch roadway and of flat top U-shape roadway were obtained. The results showed that the displacement distribution laws in the edge of roadway surrounding rock were similar between the two different roadways and the area of plasticity proportion of flat top U-shape roadway approximately equals that of vertical wall semicircle arch roadway. Based on finite element method, the bearing behaviors of the U-type steel support under the interaction of surrounding rock in vertical wall semicircle arch roadway and flat top U-shape roadway were analyzed. The results showed that, from a mechanics perspective, U-type steel support can fulfill the requirement of surrounding rock supporting in flat top U-shape roadway and vertical wall semicircle arch roadway. The field measurement of mining roadway surrounding rock displacement in Zouzhuang coal mine working face 3204 verified the accuracy of theoretical analysis and numerical simulation.

Benefit–Cost Analysis of Florida High-Friction Surface Treatments

High-friction surface treatments (HFSTs) are effective at reducing crashes on horizontal curves; however, HFST effectiveness on other roadway sections (e.g., tangents, intersections, intersection approaches) is not well documented. The crash reduction effectiveness of HFSTs in Florida was assessed, and the benefit–cost (BC) ratios for these section types were calculated. The researchers identified 23 HFST projects in Florida and attempted to collect data for each project, including bidding records, roadway geometry, and crash statistics. The cost data were based on the average comprehensive HFST unit cost and scaled by the size of the application. The benefit was estimated on the basis of 5-year extrapolations of average total and wet weather crash reductions. Savings were estimated on the basis of Florida Department of Transportation KABCO severity distribution of the crashes and an average cost per crash. On average, HFST applications on tight curves reduced the total crash rate by 32% and the wet weather crash rate by 75%. The average BC ratio on tight curve sections was between 18 and 26, depending on the benefit calculation method. Wide curve and tangents sections had few accidents initially, and HFST had negligible impact. From a crash perspective, wide curve and tangent HFST applications are not cost-effective. The effectiveness of HFST on intersection and approach applications is still inconclusive. Half the sections had good BC ratios and the other sections had negative benefit (increased crash rates). When considering the application of HFST, the engineer should consider whether there is an existing crash problem and whether it is skid related.

Numerical simulation of groundwater under complex karst conditions and the prediction of roadway gushing in a coal mine: a case study in the Guang’an Longtan Reservoir in Sichuan Province, China

Numerical simulation of groundwater in karst areas has long been restricted by the difficulty of generalizing the hydrogeological conditions of reservoirs and of determining the relevant parameters due to the anisotropy and discontinuity of the karst water-bearing media in these areas. In this study, we used the Guang’an Longtan Coal mine in Sichuan as an example, and generalized the complex hydrogeological conditions in the reservoir area. A finite element numerical flow model was used to simulate current and future scenarios of roadway gushing at the bottom of the coal mine at pile number 1 + 700 m. The results show that the roadway section corresponding to valleys has a gushing quantity of 4323.8–4551.25 m3/d before impoundment. Modeled water inflow after impoundment increased to 1.6 times the water inflow before impoundment, which threatens the impoundment as well as the roadway’s normal operation. Therefore, roadway processing measures are needed to guarantee the safety of the impoundment and of the mining operation.

차량궤적자료를 이용한 SSM 산출 방법론 개발과 적용사례 분석

Surrogate safety measure(SSM)를 이용하여 도로상의 위험을 측정하는 방식은 사고의 직접적인 원인과 연관된 차량의 거동을 분석 대상으로 한다는 장점을 가지고 있으나, 한 지점에 국한된 정보를 이용하기 때문에 위험을 연속적으로 분석하는 데에 제약이 있다. 이러한 한계를 극복하기 위해 본 연구에서는 RTK-DGPS를 이용하여 차량들의 궤적을 얻는 방안을 제시하고, 이를 통해 time-to-collision(TTC), deceleration rate to avoid collision(DRAC), acceleration noise(AN) 등의 SSM을 산출하는 데에 필요한 문제들을 고려한 방법론을 설정하였다. 또한 본 연구에서는 검토된 방법론을 이용하여 운전 중 발생하는 다양한 차량거동 변화를 관찰하기 위하여 영동고속도로 북수원IC-군포IC 구간을 대상으로 실험을 수행한 결과를 제시하였다. 그 결과 궤적 기반 SSM 지표값이 다양한 주행 상황에서의 위험성을 합리적으로 설명할 수 있음을 확인하였다. 본 연구는 향후 다양한 구간특성 및 운전자 특성에 따른 위험상황을 설명하는 연구를 수행하고, 위험구간 감지 및 위험한 운전행태의 감지를 통한 사고예방에 활용될 수 있을 것으로 판단되며, 이를 통하여 위험도로 개선 및 교통사고 줄이기 사업을 효율적으로 추진하는 데에 기여할 수 있을 것이다. Estimating the risks on the roadway using surrogate safety measures (SSM) has an advantage in that it focuses on the vehicle trajectory directly involved in conflicts. On the other hand, there is a restriction on estimating the risks of continuous segments due to the limited data collected from a location. To overcome the restriction, this study presents the scheme of acquiring the vehicular trajectory using real time kinematics-differential global positioning system (RTK-DGPS) and develops a methodology which contains the considerations of the problems to calculate the SSM such as time-to-collision (TTC), deceleration rate to avoid collision (DRAC) and acceleration noise (AN). By using the methodology, this study shows a result from an experiment executed in a section where the variation of vehicular movement can be observed from several continuous flow roadway sections near Seoul and Gyeonggi Province in Korea. The result illustrated the risks on the roadway by the SSM metrics in certain situations like merging and diverging, stop-and-go, and weaving. This study would be applied to relate the dangers with characteristics of drivers and roadway sections, and prevenst accidents or conflicts by detecting dangerous roadway sections and drivers' behaviors. This study contributes to improving roadway safety and reducing car-accidents.

Field investigations of high stress soft surrounding rocks and deformation control

Field investigations of high stress soft rock deformations show that the high stress soft rock roadway can slide with large deformation. Severe extrusion and floor heave can also be subsequently observed. The supported roadway can be locally damaged or completely fail, where the floor has a large deformation and/or is seriously damaged. The factors inducing large deformation of surrounding rocks in deep roadway are rock strengths, structure face cutting types, stress states, stress release, support patterns, and construction methods. Based on the deformation characteristics of high stress soft rock roadway, a comprehensive support scheme is proposed. The overall support technology of “step-by-step and joint, hierarchical reinforcement” for roadway is presented, and the anchor cable and bolt parameters to check the design methods are also given. Finally, the proposed comprehensive support method “bolt + metal mesh + U-steel arch + shortcrete + grouting and cable” is used in the extension section of east main haulage roadway at −850 m level of Qujiang coal mine. The 173-day monitoring results show that the average convergence of sidewalls reaches 208 mm, and the average relative convergence of roof and floor reaches 448 mm, suggesting that this kind of support technology for controlling large deformation of high stress soft surrounding rock roadway is effective.

Mobility Justice in the Context of Disaster

This article contributes to the critical mobilities literature by developing the concept of mobility justice in relation to its social justice referent. To meet this objective, we draw on two resources. Theoretically, we deploy Iris Marion Young’s theory of social justice that includes relations of institutional domination, alongside those of material distribution, as key aspects of just social relations. Empirically, we focus on the Attabad landslide, which destroyed a large section of the arterial roadway in the Gojal district of northern Pakistan, stranding those living north of the landslide. Our analysis of this mobility crisis demonstrates that state domination is an important mobility justice issue, which tends to be overlooked in studies of mobility exclusions that implicitly privilege relations of distribution. State disaster management strategies enact domination, but also render visible preexisting relations of domination that were established in the context of road infrastructure development and the region’s political liminality, and that have organized and shaped an unjust mobility regime overtime. Achieving mobility justice in post-disaster Gojal requires democratic institutional change at the state level, which will be particularly difficult to realize by this politically peripheral jurisdiction.

Development of a Budget-Prioritized Pavement Management System based on Engineering Criteria

The main objective of this study was to develop a budget-prioritized pavement management system (BpPMS) capable of selecting the most appropriate maintenance activities considering the corresponding cost-based priority for pavement maintenance and rehabilitation in Bangalore city, State of Karnataka, India. A total of 69 km of arterial roadway stretch covered with asphalt concrete pavements in one of the six zones of the city was used for pavement condition assessment and development of pavement condition indices. Since there were no previous records of pavement condition assessment, engineering criteria was recommended and developed based on the prevalent field conditions and pavement distresses. The pavement condition parametric indices were estimated using the engineering criteria based threshold indices, which were used as major inputs in the development of a BpPMS computer program. A unique feature of the ranking-prioritization based system toolkit is that it helps an agency to prefer to maintain only selective roadway network sections that are in dire need of maintenance and plan to defer actions for the rest of the sections as part of future maintenance. Overall, the approach taken in this study is a promising assessment concept which will aid an agency to implementing a network level BpPMS for the best upkeep of the region’s roadway infrastructure that would deteriorate otherwise owing to monetary constraints.

Whole-body Vibration Exposure Intervention among Professional Bus and Truck Drivers: A Laboratory Evaluation of Seat-suspension Designs

Long-term exposure to seated whole-body vibration (WBV) is one of the leading risk factors for the development of low back disorders. Professional bus and truck drivers are regularly exposed to continuous WBV, since they spend the majority of their working hours driving heavy vehicles. This study measured WBV exposures among professional bus and truck drivers and evaluated the effects of seat-suspension designs using simulated field-collected data on a vibration table. WBV exposures were measured and compared across three different seat designs:an air-ride bus seat,an air-ride truck seat, andan electromagnetically active (EM-active) seat.Air-ride seats use a compressed-air bladder to attenuate vibrations, and they have been in operation throughout the transportation industry for many years. The EM-active seat is a relatively new design that incorporates a microprocessor-controlled actuator to dampen vibration.The vibration table simulated seven WBV exposure scenarios: four segments of vertical vibration and three scenarios that used field-collected driving data on different road surfaces—a city street, a freeway, and a section of rough roadway. The field scenarios used tri-axial WBV data that had been collected at the seat pan and at the driver's sternum, in accordance with ISO 2631-1 and 2631-5.This study found that WBV was significantly greater in the vertical direction (z-axis) than in the lateral directions (x-and y-axes) for each of the three road types and each of the three types of seats. Quantitative comparisons of the results showed that the floor-to-seat-pan transmissibility was significantly lower for the EM-active seat than for either the air-ride bus seat or the air-ride truck seat, across all three road types. This study also demonstrated that seat-suspension designs have a significant effect on the vibrations transmitted to vehicle operators, and the study's results may prove useful in designing future seat suspensions.

Influence of horizontally curved roadway section characteristics on motorcycle-to-barrier crash frequency

The purpose of this study was to investigate motorcycle-to-barrier crash frequency on horizontally curved roadway sections in Washington State using police-reported crash data linked with roadway data and augmented with barrier presence information. Data included 4915 horizontal curved roadway sections with 252 of these sections experiencing 329 motorcycle-to-barrier crashes between 2002 and 2011. Negative binomial regression was used to predict motorcycle-to-barrier crash frequency using horizontal curvature and other roadway characteristics. Based on the model results, the strongest predictor of crash frequency was found to be curve radius. This supports a motorcycle-to-barrier crash countermeasure placement criterion based, at the very least, on horizontal curve radius. With respect to the existing horizontal curve criterion of 820 feet or less, curves meeting this criterion were found to increase motorcycle-to-barrier crash frequency rate by a factor of 10 compared to curves not meeting this criterion. Other statistically significant predictors were curve length, traffic volume and the location of adjacent curves. Assuming curves of identical radius, the model results suggest that longer curves, those with higher traffic volume, and those that have no adjacent curved sections within 300 feet of either curve end would likely be better candidates for a motorcycle-to-barrier crash countermeasure.

Proximity-Based Outlier Detection Method for Roadway Infrastructure Condition Data

AbstractThe quality of roadway condition data is critical for the accuracy of infrastructure management decision support systems and, ultimately, for the confidence in these systems. This paper presents a novel outlier detection method for roadway infrastructure condition data. By taking the spatial and temporal attributes of condition data into account, this method is able to detect outliers and differentiate them into gross and pseudo outliers. The method consists of two major steps. In the first step, homogenous clusters of neighboring roadway sections are identified so that sections within each cluster have the most homogeneous condition-versus-time deterioration patterns. In the second step, outliers within each cluster are detected and delineated into gross outliers (i.e., likely errors) and pseudo outliers (i.e., roadway sections affected by isolated local factors, causing their condition data to be dissimilar to their neighboring sections). The developed method was applied to roadway pavement in T...

Failure Mechanism Analysis and Support Design for Deep Composite Soft Rock Roadway: A Case Study of the Yangcheng Coal Mine in China

This paper presented a case study of the failure mechanisms and support design for deep composite soft rock roadway in the Yangcheng Coal Mine of China. Many experiments and field tests were performed to reveal the failure mechanisms of the roadway. It was found that the surrounding rock of the roadway was HJS complex soft rock that was characterized by poor rock quality, widespread development of joint fissures, and an unstable creep property. The major horizontal stress, which was almost perpendicular to the roadway, was 1.59 times larger than the vertical stress. The weak surrounding rock and high tectonic stress were the main internal causes of roadway instabilities, and the inadequate support was the external cause. Based on the failure mechanism, a new support design was proposed that consisted of bolting, cable, metal mesh, shotcrete, and grouting. A field experiment using the new design was performed in a roadway section approximately 100 m long. Detailed deformation monitoring was conducted in the experimental roadway sections and sections of the previous roadway. The monitoring results showed that deformations of the roadway with the new support design were reduced by 85–90% compared with those of the old design. This successful case provides an important reference for similar soft rock roadway projects.

Design Guidance for Bicycle Lane Widths

The objective of this research was to develop recommendations for bicycle lane width for various roadway and traffic characteristics. An observational field study involved installing temporary lane line markings to delineate bicycle lanes of varying width at midblock locations and then observing the lateral positioning of bicyclists and motorists within the roadway cross section. The final database from the field study included data for 4,965 bicyclists, 3,163 passing vehicles, and 994 parked vehicles. The primary findings of the study showed that a buffered bike lane provided distinct advantages over simply widening a bike lane and that as traffic volumes and truck percentages increased, bicyclists moved away from vehicles in the travel lane and positioned themselves closer to parked vehicles or the curb. General design guidance is provided along with recommended parking lane, buffer, bike lane, and travel lane widths most applicable to urban and suburban two-lane undivided roadways with constrained roadway width.

聚焦双频激电法煤巷超前探测土槽实验研究

基于聚焦双频激电法原理设计并制作了聚焦双频激电仪，模拟井下环境建立了土槽实验台并构造了含水异常体，给出了实验台的详细设计过程。基于垂直于煤巷断面的特殊布极方法，在无偏转条件下，通过变换屏流比和两测量电极的相对位置关系，测得在有无含水异常体下的视幅频率数据。根据数据分析得到了此条件下的最佳屏流比及最佳测量电极位置。 Focused dual frequency IP instrument has been designed and fabricated based on the principle of focused dual frequency induced polarization method. Then we established soil trough experiment platform and structured the abnormal water bearing body by simulating conditions of the coal mine, the detailed design process of experiment platform is given. Based on special electrode layout mode that the electrode is perpendicular to the roadway section, on the condition of no deflection, we got the apparent amplitude frequency data with and without abnormal water bearing body by changing the bucking current ratio and the relative position between the two measuring electrodes. And we obtained the best bucking current ratio and measurement electrode position under these conditions according to data analysis.

Operational Performance of Two-Way Left-Turn Lanes: Driving Simulator Evaluation

This study evaluated the operational performance of two-way left-turn lanes (TWLTLs) of varying widths in urban and suburban settings, in support of more flexible lane width standards for the South Carolina Highway Design Manual (SCHDM) update. Currently, the SCHDM only allows a TWLTL width of 15 ft to be used in design, and the distribution of TWLTL widths observed in a field study were justly limited; this limitation disallowed a proper evaluation of operational effects of TWLTL width. A fully integrated, high-fidelity driving simulator was used to test the operational effects of a range of TWLTL widths. Sixty participants made a series of left turns from a development driveway into TWLTLs of various widths. The TWLTL simulator scenarios included three-lane and five-lane road cross-section configurations and TWLTL widths of 12, 14, and 16 ft. Analyses were performed to determine the effects of ( a) TWLTL width on driver gap acceptance and ( b) turning-vehicle encroachments into through lanes. Analysis of variance tests indicated that TWLTL widths of 12, 14, and 16 ft had no effect on gap acceptance for three-lane and five-lane roadway sections. Trajectories were compared for a random sample of participants to evaluate the effect of TWLTL widths on vehicle encroachments into through lanes. On the basis of a subset of 30 participants, only one encroachment was observed for the scenario with a width of 12 ft, and two encroachments for the scenarios with widths of 14 and 16 ft. Greater variation in lane position was observed for wider TWLTLs, as participants took advantage of the larger space for maneuvering.

Distributions of airflow in four rectangular section roadways with different supporting methods in underground coal mines

A study has been carried out in four rectangular section roadways with different supporting methods in Yuwu Coal Company (a longwall mine), by measurements of airflow velocities in cross-section of the roadways. The asymmetrical distributions of airflow in each roadway section was obtained. The paper analyzes the low airflow velocity region of roadways through the drawing of the distributions of airflow in each roadway section. The supporting methods influence the low airflow velocity region around the roof and wall of roadways. It is shown that the low airflow velocity region increase with surface roughness of the roof and wall. The high airflow velocity region was located around the floor of the roadway with rough roof and wall. However, in the roadways with smooth roof and wall the high airflow velocity region was located around the center of section. The risk assessment should be carried out in the low airflow velocity region in the roadway with rough roof and wall. To ensure the safety of coal mining, higher volume of air intake or more smooth roof and wall of the roadways should be achieved in a dangerous zone.

Road Traffic Accident Characteristics in Dhaka, Bangladesh

Over the next decade, developing countries like Bangladesh will experience an alarming increase in road accidents and this will continue to remain as a serious challenge. Developing countries are experiencing a very high growth rate of vehicles, which is doubling the vehicle fleet in some countries in even five years. The complexity of the road environment with mixed traffic is another reality of road transportation in Dhaka, Bangladesh, where road planning and designs are not appropriate for mixed traffic conditions. Of particular concern are the urban intersections where differential approach speed is a major problem. The heterogeneity of traffic exceeding the capacity, plying of modes with varying speed and maneuvering time make the road links as well as intersections of Dhaka even more complex. The objectives of the study are to determine the characteristics of the road traffic accidents of Dhaka city for the following parameters: a) Traffic accident trend b) Traffic Control Parameters c) Traffic Accident at Junctions d) Traffic Control and Road Dividers e) Traffic Accidents and Road Geometry. Traffic accident data for the period of year 2007-2011 were collected from the Police Stations of the Dhaka Metropolitan Police (DMP) area. The data were compiled from the Police Reports accident by accident and analyzed using an MS Access based database and additionally an ArcGIS software for the selected variables. All the roadway sections and intersections of Dhaka Metropolitan Police (DMP) were considered in the study. A total number of two thousand seven hundred twenty (2720) accidents that were recorded by police during the period of year 2007-2011 were analyzed. The study revealed that a) number of accidents in Dhaka is reducing by more than ten (10) percent every year b) Sixty three percent (63%) of the accidents took place where there was no traffic control c) Only twenty nine percent (29%) of the accidents took place at intersection areas and T-junctions were found to be the most vulnerable junction type d) Seventy three percent (73%) accidents occurred on divided roadways or where only one-way traffic movement existed e) Ninety seven percent (97%) of the accidents occurred on straight road sections. Improvement of the traffic accident data collection system in Dhaka is necessary. Detailed study on under-reporting of traffic accident is also recommended.