International Journal of Civil Engineering and Technology (IJCIET) Volume 8, Issue 5, May 7, pp. 492 499, Article ID: IJCIET_8_5_56 Available online at http://www.iaeme.com/ijciet/issues.asp?jtype=ijciet&vtype=8&itype=5 ISSN Print: 976-638 and ISSN Online: 976-636 IAEME Publication Scopus Indexed DEFICIENT SHOULDER WIDTH AND ITS INFLUENCE ON ROAD CRASH FREQUENCY ON RURAL HIGHWAYS Dr. A. K. Sharma Civil Engineering Department, RCOEM - Shri Ramdeobaba College of Engineering and Management (RCOEM), Nagpur, Maharashtra, India Dr. P.D. Pachpor Civil Engineering Department, RCOEM - Shri Ramdeobaba College of Engineering and Management (RCOEM), Nagpur, Maharashtra, India Prof. T.K. Rao Civil Engineering Department, RCOEM - Shri Ramdeobaba College of Engineering and Management (RCOEM), Nagpur, Maharashtra, India ABSTRACT The aim of this research is to develop crash-prediction models for rural highways. The total of accident data is collected over a stretch of 6Km of road length from national Highway No.6 of India in State of Maharashtra. The Negative Binomial and Zero Inflated Negative binomial regression techniques are used to develop crash models. Shoulder Width Deficiency (SWD), Speed variation (LOSC), Percentage of heavy vehicles (POHV), and Volume of non-motorized vehicle (NMV) are selected as explanatory variables. It is observed that variables like shoulder width deficiency, longitudinal oscillation and proportion of heavy vehicles in traffic stream have significant impact on rural highway safety. The ability to predict accident rates is very important to transportation planners and engineers, because it can help in identifying hazardous locations, sites which require treatment. Key words: Crash Rate, Shoulder width Deficiency, Negative Binomial, Zero-Inflated Negative Binomial. Cite this Article: Dr. A. K. Sharma, Dr. P.D. Pachpor and Prof. T.K. Rao, Deficient Shoulder Width and its Influence on Road Crash Frequency on Rural Highways. International Journal of Civil Engineering and Technology, 8(5), 7, pp. 492 499. http://www.iaeme.com/ijciet/issues.asp?jtype=ijciet&vtype=8&itype=5. INTRODUCTION Countries road network plays very vital role in economic strategy. Transportation is an essential ingredient of almost everything mankind does to supply itself with necessity of life. Countries with inadequate means of movement are characterized by low standard of living. http://www.iaeme.com/ijciet/index.asp 492 editor@iaeme.com
Deficient Shoulder Width and its Influence on Road Crash Frequency on Rural Highways People, roads and vehicles form the important combination all over the world to transfer themselves or goods from one place to another. Road traffic collisions are becoming a matter of serious concern throughout the world, in terms of social, health and economic loss. Over.2 million people are killed every year globally and over million are injured or crippled. Developing countries accounts for up to 85% of all the fatalities. The problem is particularly acute in the Asia-pacific region, which has only 6% of the world s motorized vehicle fleet but accounts for 44% of global road death. Around 2, 4, people die in road crashes every year in South Asian countries. Driving or riding on an Indian Road in no more an enjoyable experience. The magnitude of road accidents in India is increasing at an alarming rate and Indian roads are becoming death traps. The latest annual statistics states that over, 46, people are killed on Indian roads. National level of fatalities per km is.25. The rural highway of developing countries accommodates heterogeneous traffic which includes many types of non-motorized vehicles other than regular traffic combination. Populations from developing countries are exposed to high risks of injury and death from road crashes owing this mixed traffic conditions. Along with shoulder width deficiency (SWD), other explanatory variables used in this study are speed variation (LOSC)), percentage of heavy vehicles (POHV), and volume of nonmotorized vehicle (NMV). The success of safety improvement programs in reducing accident occurrence depends on the availability of methods that give reliable estimates of the safety level associated with existing road locations or proposed plans and designs. Several approaches exist for estimating safety ranging from simply using accident rates to accident prediction models which relate the expected accident frequency at a road location to its traffic and geometric characteristics. Several researchers have shown that the relationship between accident frequency and exposure is frequently nonlinear, which indicates that accident rates are not appropriate representatives of safety. This finding has led most safety researchers to discard the use of accident rate as a measure of road safety and currently, accident prediction models constitute the primary tools for estimating road safety. Accident prediction models (APMs) are statistically developed mathematical models that relate the occurrence of traffic accidents to the traffic and geometric characteristics of the road. These models, the vast majority of which are negative binomial regression models, are of considerable importance to highway agencies since they can be used to conduct many traffic safety studies. 2. METHODOLOGY This study aims to develop models to quantify the impact of road geometry and traffic variables on crash rate. The study methodology consists of collecting past accident data, highway geometric data and traffic data and statistically analysing it. The road chosen for this study was National Highway no.6 in India near Nagpur City which was a two lane undivided facility during the study period. 3. DATA COLLECTION AND ANALYSIS The data in this study comprise six years of accident data, collected from 6 km of road length on National Highway no.6.from police stations and insurance companies. Road geometry and traffic data was collected through field studies and traffic count survey. For the purpose of collecting road geometry data, the road was divided into segments of similar characteristics. Data were collected from segments. Video camera was installed to measure transverse oscillation of vehicles, and image processing technique was used to measure the magnitude of oscillation of vehicles. Preliminary analysis of the data showed positive relations of many of the selected independent variable with dependent variable. The analysis suggested that the, crash rate is a http://www.iaeme.com/ijciet/index.asp 493 editor@iaeme.com
Dr. A. K. Sharma, Dr. P.D. Pachpor and Prof. T.K. Rao function of shoulder width deficiency, percentage of heavy vehicles in traffic stream, and longitudinal oscillation of vehicles (Speed variations).figures to 3 illustrates relationship of independent variables with crash rates. 25 5 4 LOSC 5 3 2 5 2 4 6 8 2 4 6 8 LOSC Figure Relationship of longitudinal oscillation with crash rate SWD 3.5 3 2.5 2.5.5 5 4 3 2 2 4 6 8 2 4 6 8 SWD Figure 2 Relationship of shoulder width deficiency with crash rate POHV 5 4 3 5 4 3 2 2 4 6 8 2 4 6 8 POHV Figure 3 Relationship of percentage of heavy vehicles with crash rate http://www.iaeme.com/ijciet/index.asp 494 editor@iaeme.com
Deficient Shoulder Width and its Influence on Road Crash Frequency on Rural Highways 4. VARIABLES The total numbers of crashes per year per km (c-rate) was selected as dependent variable, and after the preliminary analysis of the data following highly influential parameters were selected as independent variable. Longitudinal Oscillation (losc): Speed is one of the major parameter that is used as an indicator of traffic performance. The variation in the speed of vehicles in a traffic stream is one the factors that can affect road safety. The data collected showed a wide variation in the spot speed from 25kmph to 7kmph. The variation in speed with respect to modal average is taken as longitudinal oscillation in this study. Shoulder width Deficiency (swd): Shoulder provides an area along the highway for vehicle to stop during emergency. It is also considered as recovery area for drivers error. A report by Zegeer et al.(987) indicated that a paved shoulder widening of 2 feet per side reduces accidents by 6%. Shoulder width deficiency from a standard minimum (5m in this study inclusive of both sides) can be a factor with significant influence on safe operations of traffic and hence selected as a variable. Percentage of heavy Vehicles (pohv): There are two main traffic related issues associated with commercial vehicles, namely: delays that they may cause to other vehicles and the safety related impacts. It has been suggested by a number of authors that the presence of a truck in front of any other vehicle may result in the driver being more cautious due to the large size of the vehicle and the diminished sight distances. Volume of Non-motorized vehicles: Presence of Non-motorized vehicles in a traffic stream may cause frequent changes in speed of other vehicles, frequent sideways movements of motorised vehicles and minimised driving comfort level to fast moving vehicles. 4.. Quantifying the Variables Stochastic modelling techniques are used for quantifying the effects of variables on crash rate in this study. This paper presents models built using and Negative binomial regression (NBR) and Zero Inflated Negative Binomial Regression (ZINBR) Modelling form used in this study is Predicted Frequency = ε *p(y), where ε is exposure term, and p(y) is probability of y no. of accidents. Linear predictor of accident rate= + + +, and mean value of accident rate (λ) is given by, log(λ)= + + +. 5. CRASH MODEL The analysis of data was done using SPSS software. Twelve models were developed using different combination of variables using 43 accident data collected from different sections. Data illustrates that 46 segments out of were having zero accidents. Based on statistical significance five best models were selected. The analysis demonstrated strong relationship between crash rate and shoulder width deficiency. Performances of the two modelling methods selected are shown in figures no.4 to 7 Bayesian Information Criteria (BIC) is used to judge the performance of the model. Smaller BIC values suggest that likelihood of getting the desired output is more and model performance will be better. http://www.iaeme.com/ijciet/index.asp 495 editor@iaeme.com
Dr. A. K. Sharma, Dr. P.D. Pachpor and Prof. T.K. Rao No of segments 6 4 8 6 4 - Predicted Frequency Observed Frequency 2 4 6 8 2 Accident Frequency Figure 4 Predicted vs Observed frequency (Negative Binomial) No of Segments 6 4 8 6 4 - Predicted Frequency Observed Frequency 5 5 Accident Frequency Figure 5 Predicted vs Observed frequency ( Zero Inflated Negative Binomial) No. of segments 6 4 8 6 4 model-i model-ii model-iii model-iv model-v Observed Frequency 2 3 4 more than 5 Accident Frequency Figure 6 Performance of Different Models (Negative binomial) http://www.iaeme.com/ijciet/index.asp 496 editor@iaeme.com
Deficient Shoulder Width and its Influence on Road Crash Frequency on Rural Highways No. of segments 6 4 8 6 4 model-i model-ii model-iii model-iv model-v Observed Frequency 2 3 4 more than 5 Accident Frequency Negative Binomial Figure 7 Performance of Different Models (Zero Inflated Negative binomial) λ = e..... Zero-Inflated Negative Binomial... = +... = h + ( )( ) + Γ =,2 h ( ) + Γ Γ( + ) ( ) ( ) + + 6. RESULTS & CONCLUSION λ is same as in Negative Binomial This study examined the impact of shoulder width deficiency on crash occurrence on a two lane undivided rural highway in India. The research employed a 6 km stretch of rural highway, which was divided in segments on the basis of similarity of road geometry and other environmental conditions. Models were developed using negative binomial and zero inflated negative binomial regressions. The results suggest that deficient shoulders along with speed variations and percentage of heavy vehicles in traffic stream have significant impact on crash occurrence. The findings from this type of studies may help prioritize the countermeasures. Suggestion to improve safety was one of the prime objectives of this study. Accordingly following suggestions are made to improve safety based on the study results. Shoulder width Deficiency should be eliminated from both sides of the highway. Shoulder should be maintained in usable condition. Encroached shoulder should be made free from encroachment. Separate lanes for slow moving vehicles are unavoidable at present traffic scenario. Provision of lay bays should be there at frequent intervals. Enforcement measures should be imposed for parked vehicles on shoulders, sudden stoppages of vehicles on carriageway, roadside petty shops, and pedestrians on carriageway. http://www.iaeme.com/ijciet/index.asp 497 editor@iaeme.com
Dr. A. K. Sharma, Dr. P.D. Pachpor and Prof. T.K. Rao Speed limit enforcement is not required only for maximum speed but also for minimum speed, so that the variation in speed is minimum. At the planning stage only, lanes separated from motor-way should be provided for motorcycles, slow moving and non-motorized traffic. This will segregate vehicle with similar dynamic and static characteristics and more uniform flow will follow. REFERENCES [] Road Accident In India-5 [2] Anna K. Andersson, Lee Chapman, The impact of climate change on winter road maintenance and traffic accidents in West Midlands, UK, Accident Analysis & Prevention Volume 43, Issue, January, Pages 284 289 [3] Chao Wang, Mohammed A. Quddus,Stephen G. Ison, Impact of traffic congestion on road accidents: A spatial analysis of the M25 motorway in England, Accident Analysis & Prevention Volume 4, Issue 4, July 9, Pages 798 88 [4] David W. Soole, Barry C. Watson, Judy J. Fleiter Effects of average speed enforcement on speed compliance and crashes: A review of the literature, Accident Analysis & Prevention Volume 54, May 3, Pages 46 56. [5] Garber, N.J., Wu, L, Stochastic models relating crash probabilities with geometric and corresponding traffic characteristics data, Research report No UVACTS-5-5-74 Center for transportation studies at the University of Virginia 989 [6] Garber, N. & Joshua, S., Traffic and geometric characteristics affecting the involvement of large trucks in accidents. VDOT Project No.: 9242-62-94, Virginia Transportation Research Council, University Station, Charlottesville, Virginia 99. [7] Kalakota, K.R., Seneviratne P.N. & Islan, M.N. Influence of geometric design variables on accidents rates on two lane rural highways, International conference on road safety in Europe, FERSI Berlin, 992. [8] Kockelman, K. and Shabih, R. Effect of Light-Duty Trucks on the Capacity of Signalised Intersections. Journal of Transportation Engineering, 26(6),pp. 56-52,. [9] Krammes, R. and Crowley, K. Passenger Car Equivalents for Trucks on Level Freeway Segments. Transportation Research Record, 9, pp. -7,987. [] Lingzi Cheng, Srinivas Reddy Geedipally,Dominique Lord, The Poisson Weibull generalized linear model for analyzing motor vehicle crash data, Safety Science, Volume 54, April 3, Pages 38 42 [] Milton, J.C., Shankar, V.N., Mannering, F.L. Highway accident severities and the mixed logit model: An exploratory empirical analysis, Accident Analysis and Prevention Volume 4, Issue, January 8, Pages 26-266 [2] Miaou, S.P.(994) The relationship between truck accidents and geometric design of road sections: Poisson versus negative binomial regressions, Accident Analysis and Prevention vol. 26, issue 4, pp. 47-482 [3] Molina, C. Development of Passenger Car Equivalencies for Large Trucks at Signalised Intersections. ITE Journal, November, 987. [4] Okamoto (989), A Method to cope up with random errors of observed accident rates Safety literature, Vol.4, page 37-332. [5] Sharma A.K., Landge V.S.(2), Pedestrian Accident Prediction Model For Rural Road, International Journal of Science and Advanced Technology Volume 2, No 8 http://www.iaeme.com/ijciet/index.asp 498 editor@iaeme.com
Deficient Shoulder Width and its Influence on Road Crash Frequency on Rural Highways [6] Zegeer, C.V., Reinfurt, D.W., Hummer, J., Herf, L. & Hunter, W., Safety effects of cross-section design for two-lane roads, Transportation Research Record, No. 95,987 pp. 23-32. [7] Zegeer, C V., Deen, R. C. & Mayes, J. G. Effect of lane and shoulder widths on accident reduction on rural two-lane roads. TRR 86 98.pp 33-43 [8] Zuduo Zheng, Soyoung Ahn, Christopher M. Monsere, Impact of traffic oscillations on freeway crash occurrences, Accident Analysis & Prevention Volume 42, Issue 2, March, Pages 626 636. [9] Bhasker Vijaykumar Bhatt and Kamlesh Chinabhai Chandpa, Road Crashes and Losses in Surat City and Umra. International Journal of Civil Engineering and Technology, 5 (5), 4, pp. 5-3. http://www.iaeme.com/ijciet/index.asp 499 editor@iaeme.com