Estimating Traffic Volume to Identify the Level of Service in Major Intersections of Rajshahi, Bangladesh

The increment of vehicles due to the proportional increment of populations and a rapid development of modern society is a major concern in Metropolitan cities in developing countries like Bangladesh. So, it is imperative to monitor traffic volume as well as the quality of transport supply termed as the Level of Service (LOS). The present study is an investigation of the behavior of mixed traffic flow in Rajshahi city of Bangladesh. Field Traffic volume survey was carried out to determine the level of service at 3 major Unsignalized intersections in Rajshahi city corporation (RCC). Level of service (LOS) was determined by volume capacity ratio and peak hour factor (PHF) method. Nature of traffic flow in Rajshahi city is heterogeneous. So, this heterogeneous or mixed traffic are simplified by Passenger car unit (PCU). Then estimated PCU was used to determine LOS. LOS was calculated for both directions of roads. Auto rickshaw, easy bike and Rickshaw are the dominant vehicles in Monicottor, Vodra, and Laxmipur intersection. According to PHF method and V/C ratio method, LOS of Monicottor intersection is very unstable and worst. At Vodra intersection which consists of three legs, Talaimari to Vodra lane contains highest traffic volume at evening peak and the LOS of Vodra to Padma Residentail area is very worst in nature after analyzing both V/C ratio and PHF method. Considering and evaluating all the findings it can be recommended that Restriction for truck movement in daytime should be applied in Monicottor intersection and width of Monicottor to Sondighir mor and Vodra to Padma residential area road need to be increased to make the traffic flow suitable. Also, incorporation of an effective traffic signal, traffic rules and regulation should be applied and maintained properly in the worst condition intersection to accelerate the traffic flow in RCC area.


Introduction
For the economic development, good transportation system is very important [1][2][3]. In transportation engineering traffic volume study is a baseline. Engineering operations and management are successfully completed by using it [4]. Traffic Volume survey plays a significant role to determine the existing condition and to forecast the future condition of traffic volume [5]. The road traffic in developing countries like Bangladesh are highly heterogeneous comprising of the traffic of different static and dynamic characteristics [6,7]. Again, Traffic volume data is very important as it is used to estimate capacity of a road and level of service of that given road under the combination of traffic at any hour of a day [8,9]. LOS of a traffic facility defines as a concept used to determine the performance and quality of traffic service to a given flow rate [10]. Levels of service are defined as six categories from A to F and category. A represents best operating condition on the other hand F represents the worst [11].
In Rajshahi city, the increment of traffic volume and congestions are two quickly developing problems. Nowadays, it is common to see traffic congestions at intersections at peak hours in the morning and evening. According to a report, traffic volume is increasing in last few decades and was 19397 in 2015 with annual growth rate 6.1% in this city [12]. This may be due to Poor road planning and sub-standard geometric conditions of selected intersections [13]. Intersections become very congested if traffic volume are high, make inefficiency as a result peoples suffer delay and frustration [14]. A rapid escalation in the number of motor vehicles, greater availability of used vehicles, the relative reduction in prices result traffic congestions [15]. Due to traffic congestion, air pollution, fuel usage, and travel time [16,17]. Therefore, it is a significant issue to investigate traffic volume and to monitor the quality of transport supply in terms of level of service for major intersections of Rajshahi city corporation (RCC). Traffic volume count of this study will be helpful for planning, accident analysis [18], design and operation, for roadway of Rajshahi city [19] as well as future traffic demand forecasting.
To estimate traffic volume at selected intersections, a case study was made at 4 major intersections during morning (8am-10am), noon (12pm-2pm) and evening (4pm-6pm). To analyze mixed or heterogeneous traffic, a simplification is developed by (add authors name) to convert the different types of vehicles into equivalent number of passenger cars named Passenger car unit or PCU [6]. Finally estimated PCU value are used to determine LOS on three or four legs divided intersections. Level of service (LOS) was determined by volume capacity ratio and peak hour factor method.

Literature Review
LOS is very effective approach to identify the existing traffic condition of any intersection. Numerous studies have been conducted by different researchers in which they describe the procedure about how to calculate the LOS using various methods.

Related Works in Foreign Countries
A concept was first developed in 1965 for highway named highway capacity manual (HCM) to define level of service and classify it by a range from A to F for highway [20]. It is very important to analyze the traffic performance for design, maintenance, rehabilitation, and planning of roads. Performance evaluation of traffic in a highway is expressed by a term Level of service. It is a method which can explain traffic conditions for an existing or proposed transportation facility operating based upon current or projected traffic demand [21]. Capacity and level of service are analyzed to get the delay of the analyzed facilities. This Analysis is two types. One is empirical, another is analytical. The empirical model is established on the basis of regression analysis on the other hand the analytical model is based on the gap-acceptance theory [22]. An attempt is made by Ankit N Mahidadiya and Prof. Jayesh Juremalani to estimate passenger Car unit (PCU) in an urban intersection [23]. A study was made in malaysia by jamil et al. using aaSIDRA (full abbreviate of aaSIDRA) intersection version 5.1 software to analyze capacity, level of service at unsignalized intersection. Main purpose was to analyze factors affecting level of service at a junction [24]. Rao et al. followed HCM (highway capacity manual) 2000 to evaluate the capacity, control delay and Level of service of vehicular streams and traffic parameters were abstracted by the videography for 3 uncontrolled intersections in India [25]. Mithun Mohan and Satish Chandra proposed three methods for the estimation of PCU at UI under highly heterogeneous traffic conditions. First one is PCU based on occupancy time, second one is PCU based on potential capacity, and last one is PCU based on queue clearance rate [26].

Related Works in Bangladesh
Several research programs have been developed in foreign countries, but very limited studies have been made in this selected topic in Bangladesh. A case study like physical feature s survey, delay time survey, parking survey, traffic volume survey was done to find out the condition of traffic and transportation at Central Business Area of Rangpur city [27]. A study was developed by chisty, islam and mishuk to identify the existing level of service of agrabad to CEPZ Road in Chittagong city. To calculate LOS, a traffic survey was carried out to determine traffic volume, capacity, and speed of that existing road [28].

Related Works in Study Area
During the literature review, there are no studies were found about estimation of traffic volume at intersections to calculate level of service at intersections in Rajshahi city.

Description of Study Area
Rajshahi is a metropolitan city in Bangladesh and a major urban, commercial and educational Centre of North Bengal [29]. The study is carried out in Rajshahi City Corporation, located in Northwest part of Bangladesh. There are 4 thanas (Administrative Unit) in Rajshahi City Corporation which include 30 wards Figure 1. There are 10 city corporations in Bangladesh and Rajshahi is one of the oldest city corporations, which is established in 1991 [29]. In the previous decade Rajshahi is called a city of rickshaw but now it is called a city of both rickshaw and auto-rickshaw and easy bike [2]. In Rajshahi city, 63% commercial vehicles transport passenger and carry freight [12]. The nature of all intersections is Non-signalized. Most busy intersections were selected named Vodra, Laxmipur, Monicottor.

Road Geometry of Intersections
Three roads intersected at Vodra intersection are Talaimari-Vodra, Railway Station-Vodra & Padma Residential area-Vodra. A sculpture is situated named "Smriti Amlan" in the center of intersection which radius is 40 feet. The Talaimari-Vodra road has four lanes. The "Railway station-Vodra" road has four lanes with two sided footpath. The Padma residential-Vodra road has two lanes with two-sided footpath Figure 1. Laxmipur intersection consists of four roads named Bazar to Laxmipur, Railgate to Laxmipur, C&B to Laxmipur & court station road to Laxmipur. In the Centre of intersection, a sculpture is situated named Mintu mia chottor and its radious is of the center is 29ft. Court station road is two lanes and other road is four lanes Figure 2.

Methodology
The main objective of this research is to identify the LOS of different intersections. LOS is related with Modal composition of various transport, Road capacity and Road geometry. Modal composition describes the key operational, commercial advantages and properties of any transport in terms of cost, speed, accessibility, frequency, safety, comfort, etc. In this research to achieve the LOS, traffic volume survey was carried out to count mixed vehicles, geometric feature survey. All traffic data were collected into three phases like morning peak (8-10am), afternoon off peak (12-2pm) and evening peak (4-6pm) and each peak was continued for 2 hours duration (Transport, 2004). Geometric feature survey is needed to identify the existing road capacity. To identify the existing supply and capacity conditions of various intersections road length, width of carriageway, footpath, median, shoulder, number of legs and control system etc. data has been collected by conducting field survey. The calculation of Passenger car unit or PCU is very important to analyze the mixed or heterogeneous traffic and PCU is a simplification which convert the different types of vehicles into equivalent number of passenger cars [26]. By conducting a private survey in 2014, 11,000 battery operated auto-rickshaws, 35,000 rickshaws, 800 CNG-rickshaws and auto-tempos, 1,500 human hauler, 1,200 rickshaw vans and 1,500 cars and micro-buses are investigated [3] (Table 3). To estimate the LOS two useful methods have been applied. The volume-capacity ratio is 1st of them. Volume capacity ratio (V/C) is one of the most used index to assess traffic status in cities, in which V is the total number of vehicles passing a point in one hour and C for the maximum number of vehicles that can pass a certain point at the reasonable traffic condition, "Volume -Capacity Ratio (V/C) is a measure that reflects mobility and quality of travel of a facility or a section of a facility. It compares roadway demand (vehicle volumes) with roadway supply (carrying capacity) [18]. The V/C method is associated with LOS and determining how well a roadway is performing. This measure can alert transportation providers to areas where traffic mitigation measures should be considered. V/C ratio was calculated by following formula [30,31]. (1) The 2nd method to calculate the LOS is Peak Hour factor (PHF) method. Traffic engineers focus on the peak-hour traffic volume in evaluating capacity and other parameters because it represents the most critical time. The analysis of level of service is based on peak rates of flow occurring within the peak hour because substantial short-term fluctuations typically occur during an hour. Common practice is to use a peak 15-minute rate of flow. Flow rates are usually expressed in vehicles per hour, not vehicles per 15 minutes. The relationship between the peak 15-minute flow rate and the full hourly volume is given by the peak-hour factor (PHF) as shown in the following equation (Authority, 2003). Peak-hour factors in urban areas generally range between 0.80 and 0.98. Peak-hour factors over 0.95 are often indicative of high traffic volumes [32]. PHF was evaluated by the following formula [31].

Results and Discussions
To fulfill the objectives of the study, data analysis has been done on two stages. First, analysis on existing conditions of intersections has been conducted. Secondly, survey data have been conducted to find out the recent traffic performance conditions of these intersections. In mixed traffic condition, modal share is an important factor for assessment of intersection performance.

Moni-Cottor to C & B lane:
It is noticed that most vehicles about 1060/hour used by public than other vehicles are autorickshaw at evening hour. There is no separate lane constructed for such type of vehicles. Second dominated vehicle is rickshaw and paddle rickshaw and their peak value 359 vehicles/hour and 249vehicles/hour respectively were found both at afternoon off peak. Afternoon off peak contains maximum number of vehicles in most of the case. Less dominant vehicles are bus, truck, private car, Emma. Moderate dominant vehicles are motor cycle, rickshaw, paddle rickshaw and bi cycle. Their peak value fluctuates at any peak hour (either morning or afternoon peak or evening peak) Figure 6.

Temporal Variation of Three legs of Moni-chottor
Intersection: Intersection to zero-point leg has 3496 PCU/hour which contains the highest PCU/hour among the three legs at afternoon-off peak. Second one is intersection to zero-point leg and last one is sonadighi leg contain 2242pcu/hour and 452.5pcu/hour at afternoon off peak and evening peak respectively Figure 9.

V/C Ratio Method
Analysis shows that in Zero Point to CNB lane & CNB to Zero Point lane traffic volume is more than its capacity in three periods of time. Only sonadighi lane fell within A category in 3 peaks. Rest of the lanes satisfy level of service of F category. By following V/C ratio method LOS of Monicottor intersection is F category in three periods of time Table 4.

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Laxmipur to C & B lane: High concentration of vehicle in Laxmipur to CNB lane is easy bike. Amount of such type vehicle is 381 was found in evening hour. No truck, human holler influence in this lane. Only one bus was found during afternoon off peak. At evening, morning, afternoon off peaks concentration of auto-rickshaw, paddle rickshaw and bi cycle were maximum. Concentration of van, micro bus, mini truck is limited, their percentages are about 45%, 55% and 47% at morning, about 43%, 38%. 40% at afternoon off peak and rest of the percentage exist at evening respectively Figure  11.

Rail Station to Laxmipur:
In This lane, dominant vehicle is easy bike. At morning highest concentration of easy bike was found and its amount is 517. Second dominant vehicles are paddle rickshaw, auto rickshaw, bi cycle, motor cycle, private car and their percentage are about 33%, 35%, 59%, 45%, 53% at morning, 35%, 37%, 25%, 35%, 25% at afternoon off peak and rest of the percentage of vehicles found at evening respectively. Low volume of traffic like Truck, human holler was found in this lane. Less dominant vehicles were mini truck, micro bus, van and bus Figure 12.

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Laxmipur to Court lane: Large volume of vehicle is easy bike. Human holler was found only morning peak. Percentage of paddle rickshaw, auto rickshaw, bi cycle, motor cycle, and private car are 28%, 29%, 35%, 36%, 43%, at morning, 40%, 42%, 43%, 30%, 35%, at afternoon off peak respectively. Rest of the percentage was found in evening hour peak. Less influenced vehicles were van, micro bus, mini bus and bus Figure 17.

Temporal Variation of Different Legs of Laxmipur
Intersection: Laxmipur intersection to bazar leg contain highest amount of PCU/hour at morning hour and this value is 1432.95 PCU/hour. Lowest PCU/hour looked through at Laxmipur intersection to CNB during afternoon off peak. The location of highest concentration of PCU/hour for afternoon off peak and evening were CNB to Laxmipur leg and court to Laxmipur leg respectively.

Level of Service
V/C Ratio Method: By comparing between given V/C ration and standard V/C ratio, the highest LOS in respect of V/C ratio at morning peak, afternoon off peak, evening peak are C, C and B and their respective locations are Laxmipur to bazar lane, court to Laxmipur lane and Laxmipur to court lane. According to V/C ratio, LOS of Laxmipur intersection is C by considering all lanes.
Peak Hour Factor Method: According to PHF method the LOS of Laxmipur intersection is F compared to standard PHF. At morning highest PHF is C in CNB to Laxmipur lane, Laxmipur to CNB lane and Laxmipur to court lane. At afternoon off peak, evening peak the highest PHF is F in bazar to Laxmipur lane and Laxmipur to bazar respectively. By considering and analyzing two methods the LOS of Laxmipur intersection is F which is worst among all category.

Vodra Intersection
Talaimari to Vodra: Majority of vehicles in this lane congested during evening. Dominant vehicle is easy bike (temp) which amount is 390 vehicles/hour found at evening. Less influenced vehicles are micro bus, mini truck, mini truck (temp), trolley, CNG, human holler

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Vodra contain highest LOS at evening, morning and afternoon off peak respectively. The final LOS in this intersection is F Table 9.

Causes of Congestion in Intersection
Moni-chottor intersection plays as a main commercial hub of Rajshahi city. This is the main reason of rising auto-rickshaw volume in Moni-chottor intersection. Traffic flow in afternoon off-peak is higher than other two peak hours. This is may be due to Monichottor intersection is located near educational zone. The factors for greater traffic flow from Zero point to Intersection is the land use containing important establishments like Rajshahi Collegiate School and College, Rajshahi College, a large Kaccha Bazar, Janata Bank Corporate Bank, etc. As the effective carriageway width is only 12 feet, the LOS of these two lanes is F. Less rent and quickly reached in destination are one of the major reason to get the majority and popularity of increase amount of auto-rickshaw [3]. Some probable reasons behind the fascination of using CNG by operators as well as passengers were investigated. Attractive advantages like Reduction of maintenance cost, emissions of 20-30% fewer greenhouse gas, environmentally friendly behavior, superior to petroleum-based products diverted and motivated the operators to use such type of vehicles [33].

Effect of Congestion in intersection
One of the major disadvantage is uncontrolled or non-signalized intersections. This is also known as priority-controlled intersection. It provides no indication to the driver's concern when vehicle approaches to enter the intersection [34] Low priority movement on minor roads cause delay that influence the performance of such type intersection very strongly. As a result, vehicular conflict creates which is responsible for accident and congestion [35]. LOS of three intersections was F. Level of service F means in an intersection vehicle are forced to move and speed of vehicles are too low [36]. Commercial and educational activities around Monicottor intersection attract people so why LOS of Monicottor is very low. Again, all the vehicles pass this intersection very slowly. In recent time traffic jam happens in this intersection. Few lanes contain higher flow rate than their required capacity. If traffic flow equals or less than capacity Collision between vehicles, low mean speed, frequent unexpected stoppage will occur [37]. Congestion occurs due to excess traffic demand and inefficient road operations [38].

Accidents Data Analysis in Rajshahi City due to congestion in intersection
Several tremendous accidents occur in Rajshahi city due to non-signalized intersections. At Dayingpara intersection on Chapainawabganj-Rajshahi road, a truck ran over a truck helper [39]. At Northern intersection under Talaimary area, A truck and an auto-rickshaw collided and two peoples on spot [40]. A bus plunged into a roadside ditch at Kadirpur Jamadarni intersection in Godagari upazila of Rajshahi and result at least 25 peoples were injured [41]. One was killed and another other one was injured near Mohonpur police station intersection in Rajshahi [42]. By sandwiching between two trucks uncle and his nephew killed at at Talaimari intersection in Rajshahi city [43][44][45].   Flow rate of vehicle is maximum at monicottor at three peaks. Second one is Vodra intersection. Lowest peak was observed at Laxmipur intersection among all Figure 26. By inspecting selected intersections, the major or dominant vehicle is auto rickshaw in monicottor. That's why, this is the more congestive intersection. The influence of easybike (temp) only dominant in Vodra intersection. Second dominant vehicle is easy bike or motor cycle Figure 27.

Conclusion
The traffic flow behavior in heterogeneous traffic in Rajshahi city is observed that is absolutely complex. Highest concentration of dominant vehicle (easy bike/CNG) is found in the morning peak period (12 pm-2 pm) at Laxmipur to bazar determined by using modal variation. Laxmipur intersection to bazar leg contain highest amount of PCU/hour at morning hour by using temporal variation. According to V/C ratio and PHF the LOS are C and F respectively. The final LOS of Laxmipur intersection is F. In case of Vodra intersection, highest concentration of vehicles are easy bike/CNG and easybike (temp) found in all lane. The maximum road space are covered by easy bike. Evening peak contains large volume of vehicles determined by using temporal variation. Vodra to Talaimari lane contain large amount of volume during evening. The existing volume of Padma R/A to Vodra lane at morning, Padma R/A to Vodra lane, Vodra to pdma R/A lane at afternoon off peak and evening peak are higher than their standard capacity. LOS of this intersection is F. At monicottor intersection, auto rickshaw is the dominant vehicle in all lanes. Traffic flow in afternoon off-peak is higher than other two peak hours in CNB-Zero point because traffic flow from different three direction mix here. The volume of CNB-Zero point lane, Zero point to CNB lane at afternoon off peak and morning are higher than their standard capacity. According to Peak Hour Factor Method, LOS of Monicottor intersection is E category at its highest peak. According to V/C ratio method, LOS of Monicottor intersection is F category. So, final LOS is F. Carriageway width should be increased. Local Govt. authority should take necessary steps to improve the condition of these selected intersection.