Car Delay Time near a Curbside Stop under Mixed Traffic.doc
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1、精品论文Car Delay Time near a Curbside Stop under Mixed TrafficCondition5YANG Xiaobao, HUAN Mei, FAN Aihua, DONG Ling, LI Ming(MOE Key Laboratory for Urban Transportation Complex Systems Theory and Technology,Beijing Jiaotong University, Beijing 100044)Abstract: This paper proposes a delay model to cars
2、 under mixed traffic flow near the curbside stop based on queuing theory. Bus stream system is described by an M/M/k queue and the service counter is10the bus stop. The conflict between different streams at the stop is developed by the advanced Markovian model with unequal arrival rates and unequal
3、service rates for customers of two major types. The delay to cars near the stop under mixed traffic flow can be derived by the queuing models. Theaverage car delay is estimated as the sum of the average delay at the conflict points between differentstreams, and the delay resulting from following the
4、 slower bicycles that merged into the motorized lane.15Car delay model is the function of three types of traffic streams with buses, cars and bicycles. The proposed model may be applicable to design and operational analysis of bus stops in other Asiandeveloping countries.Key words: Delay time; bus s
5、top; mixed traffic flow; queuing theory200IntroductionAs the first point of contact between the passenger and the public transit service, the bus stop is a critical element in a transit systems overall goal of providing timely, safe, and convenient transportation. In recent decades, many studies hav
6、e been conducted on the the location 1, design2-3 and operations 3-4 of bus stops and obtained many useful achievements. In addition, other25researchers mainly focused on the effects of bus stops on traffic flow 5-8. On the bus stop, unfortunately, little information has been published concerning bu
7、s stops with non-motor vehicles.As a developing country, China has her own traffic characteristics. Mixed traffic between non-motor vehicles and motor vehicles is an important traffic type in China. Some survey show that non-motor vehicles, mainly bicycle is still one of the more sustainable modes t
8、han motor30vehicle travel in China. Typically, there are three types of bus stops in urban areas: the curbside stops, bus bays, and bus boarders 9. And curbside stops are the most common bus stops in many Chinese cities. Fig. 1 presents a sketch map for mixed traffic streams at a typical curbside st
9、op and will be referred to in the following discussions. Firstly, there are two lanes on the urban roadway: one is the bicycle lane and the other is the motor lane. Secondly, there are three types of traffic35streams: bicycle stream, bus stream, and car stream. Thirdly, bus stop is usually located o
10、n the bicycle lane. When a bus dwells at the curbside stop, bicycles will change to the motor lane and round the stopped bus. Thus, the presence of a stopped bus creates a temporary conflict between bicycles and cars, reducing the road capacity and increasing the vehicles travel time. Similar phenom
11、ena may be found in other Asian developing countries, for example, India, Malaysia,40Vietnam, Cambodia, etc.Foundations: Specialized Research Fund for the Doctoral Program of Higher Education of China (No.20090009120015), National Natural Science Foundation of China (No. 70901005, 71131001), Nationa
12、l BasicResearch Program of China ( No. 2012CB725401)Brief author introduction:Yang Xiaobao(1981-), male, associate professor. His research interest is including transportation engineering, traffic behavior and safety. E-mail: - 7 -Fig. 1 Curbside stop with mixed traffic streams among buses, cars and
13、 bicyclesDue to the special features of mixed traffic, the existing traffic models of bus stops developed45according to the traffic conditions in developed cities might not be applicable to developing cities.Therefore, it is necessary to deeply study mixed traffic flow between motor vehicle and non-
14、motor vehicle. In recent years, some researchers have realized this particularity, and correlative work is being done, but it still has a long way to go. KOSHY and ARASAN 9 used simulation technique to study the impact of bus stop type on the speeds of other vehicles under heterogeneous50conditions.
15、 YANG et al. 10-11 established capacity models near the curbside stop with bicyclesbased on gap acceptance theory and conflict technique. However, no information was found in the literature on delay time at the bus stop with mixed traffic flow. Because no traffic streams near a bus stop under mixed
16、traffic condition possess the absolute priority of driving, the conflict between different streams (e.g. the car-bicycle conflict and the car-bus conflict) at the stop can be55described by the queuing model with no priorities but unequal service rates for customers of two major types. This paper inv
17、estigates delay time to cars near the bus stop with mixed traffic flow. Firstly, mixed traffic flow characteristics on bus stops are analyzed. Then, the delay model based on queuing theory is proposed. Next, the delay model is validated by field data in Beijing. Finally, conclusions and future resea
18、rches are given.601Mixed Traffic Flow Characteristics at the Curbside Stop1.1Bus stream: M/M/k queuing modelConsider a road link near the bus stop as shown in Figure 1. A sophisticated queuing theory model can be developed by the assumption that the simple bus stream system can be represented by an
19、M/M/k queue. The service counter is the bus stop. The input of the queuing system in65equilibrium, as well as the output, is formed by the buses approaching from upstream which are assumed to be negative exponentially distributed arrival headways with mean 1/ lb . The dwelling time at the stop is th
20、e service time, which is also assumed to be independent and negative exponential distributed random variables with mean sb . Finally, the “k” in M/M/k stands for k identical servers, i.e. the number of existing berths at the bus stop.70For the M/M/k system as a general property, the probability of t
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