Main Influences in Modelling and Simulation of Urban Traffic Flows

Transcription

1 Proceedings o the 2nd International Conerence on Environmental and Geological Science and Engineering Main Inluences in Modelling and Simulation o Urban Traic Flows JANOS TIMAR, DANIELA FLOREA, CORNELIU COFARU, DINU COVACIU Faculty o Mechanics Transilvania University o Brasov B-dul Eroilor nr.2, Brasov ROMANIA jamcsika_timar@unitbv.ro Abstract: - Traic modelling and simulation is an increasingly used and eective tool or analyzing a wide variety o dynamical problems which are not suitable or study by other means. This research paper presents a real application or the urban area, more precisely in Brasov city, where there was noticed some problems in the urban traic: congestions, conlict points. The data collected or one o the busiest arterial streets o the city has represented the input data or the modelling and simulation program Synchro plus Simtraic 6. A new solution was proposed based on the analysis o the main inluences o road geometry, signalisation and traic conditions. Key-Words: - Traic simulation, traic modelling, urban mobility, road saety, traic lows, adjustment actors.. Introduction The researches perormed in a very congested area o Brasov city, usually named the big roundabout, permitted to identiy the real problems generated by the last solution or urban traic management: traic jams, many conlict points between vehicles and weaving o traic lows. The map o area o interest is shown in Fig.. traic volumes or a representative period in a day is presented in Fig.2. number o vehicule Vehicle distribution per lane acces rom Toamnei street lanes :00-:5 :5-:30 :30-:45 :45-0:00 Fig.2 Traic volumes at Toamnei Street Fig. The map o studied area 2. Data acquisition Ater a general analysis o the area in order to identiy the actual, many activities were organised to prepare, measure and analyse the traic lows. Thus, arrival patterns, traic volume distribution in the entrance o each signalised or unsignalised intersection were established. The variation o 2.. Evaluation o the saturation low rate Capacity analysis o the area can be made only ater the identiication o the saturation degree o each intersection. The ideal saturation low rate, S or the group o lanes at the entry o a signalized intersection, expressed in unitary vehicle per hour (V t /h), is inluenced by the ideal saturation low, S 0, the number o lanes N, and a very important number o adjustment actors i as in relation (). S = S N () 0 i i= Computation is based on the ideal saturation low considered as 00 V t /h/lane. A realistic result o ISSN: ISBN:

2 Proceedings o the 2nd International Conerence on Environmental and Geological Science and Engineering 800 V t /h/lane is i someone consider the gap between the ollowing vehicles are 2 seconds. Adjustment actors The main inluences o modelling contained by the adjustment actors, are presented in the ollowing equations [3]. Lane width, W ( W 3.5) = + (2) The value 3,5 represents the standard width o a lane. The variation o the lane width rom the standard 3,5 m to 4,0 m produce a variation o the adjustment actors in the,0,06 limits corresponding with the increase 5,6% o ideal saturation low rate S, expressed in unitary vehicle V t /h/lane (Table ). Table Lane width, m 4 3, 3,8 3,7 3,6 3,5,06,04,03,02,0 S, Vt/h Reducing the lane width rom 3,5 m to 2,5 m produce a variation o the adjustment actors in the,0 0,8 and as consequence reducing the traic volume to,%, that means 800 Vt/h/lane to 800 Vt/h/lane (Table 2). Table 2 Lane 3,5 3,3 3,2 3, 3 2,8 2,7 2,6 2,5 width, m 0,8 0,7 0,6 0,4 0,2 0, 0, 0,8 S, Vt/h Heavy vehicles 00 2 = (3) 00 + % HV ( E T ) The percentage o heavy vehicles, %HV has an important inluence in traic lows. This value is between 0 30% and produce a variation o the adjustment actors 2 in the limits 0,77,00 and at the same time a decrease o the ideal saturation low rate with 23% (table 3). The ormula considers also the coeicient E T to transorm the heavy vehicles in unitary equivalent (passenger cars). Table 3 Heavy traic, % ,6 0,3 0, 0,83 0,77 S, Vt/h Grade % G 3 = (4) 200 I intersection is located in an area where the road is tilted as a consequence this will generate to increase traic low by 3% (when the grade %G on lane group approach is -6%) and grade ranged rom 0% to 0%, a decrease o 5%. The area studied is located on the ground horizontally so there is no inluence. Parking 8N m N = (5) N Locations o parking near signalized intersections aect negatively the low o saturation, especially in the case o a single lane in the movement direction. The coeicient 4 varies in this case the value o.00 when there is no parking at the 0.7 to be carried out when the number o parking N m is 40 parking manoeuvres per hour. In this case the reduction o traic is 30%. Bus blockage 4.4N B N = (6) N N B number o buses stopping/h within 75 m upstream or downstream o the stop line, taking into account when the stopping buses block traic low in the considered lane group. Lane utilization 6 = v g /( vg N) (7) V g unadjusted demand low rate or the lane group, expressed in vehicles per hour. V g unadjusted demand low rate on the single lane group with the highest volume. Let turns (LT) The consideration o this actor takes into account the two s. For exclusive lane: = 0.5 7, and or shared lane: 7 =, (8) P LT where, P LT proportion o LT s in lane group. ISSN: ISBN:

3 Proceedings o the 2nd International Conerence on Environmental and Geological Science and Engineering Right turns (RT) For exclusive lane: = , or shared lane: 8 = (0.5)P RT () and or single lane 8 = (0.35)P RT. (0) The main parameter is P RT, proportion o RT s in lane group. Pedestrian bicycle blockage LT adjustment =.0 PlT ( ApbT )( PLTA ) () RT adjustment =.0 PRT ( ApbT )( PRTA ) (2) P LT and P RT proportion o LT s and RT s in lane group, A pbt permitted phase adjustment, P LTA and P RTA proportion o LT, respectively RT protected green over total LT green 3. Proposal or new solution The critical analyses o modelling and simulation results permitted to ormulate a new proposal. With the proposed solution it modiies the sense o change and movement o traic, which runs oneway only on a certain segment o the route, rest in two-way The traic will be conducted by the proposed study in two directions so the volume o traic is higher rom the intersection M. Kogalniceanu - Bd November 5 - I. Maniu intersection to Bd November 5 Toamnei Street Zizinului Street Calea Bucureşti. With the implementation o this solution, two actors have remained unresolved: the noise and possible points o conlict pedestrian - vehicle and vehicle-vehicle. Fig.3 Real scheme o the route Fig.4 Proposed scheme o the route The intersection named B-dul Hărmanului Toamnei Street B-dul M. Kogălniceanu is an intersection with three branches and two accesses (Toamnei Street, and B-dul M. Kogălniceanu). The proposed intersection scheme will have an actuated control type. This actuated control type would require installation o inductive loops and connecting them to a central unit. Another change is that the intersection will have 3 accesses and on Toamnei Street will come back in two-way traic. Beneits o the actuated control type: Increase the capacity o movement Reduce delays Allows synchronization o the signalized programs Access to the intersection will be done according to the request in this way advantaging the main traic lows. In the study we had made one o the ollowing problems had been identiied in the intersection: queues that orm on the Toamnei Street ISSN: ISBN:

4 Proceedings o the 2nd International Conerence on Environmental and Geological Science and Engineering Fig.5 Queues in the simulation sotware Conlict points o vehicle-vehicle appeared in traic lows between the two accesses o the intersection (Bdul Harmanului and Toamnei Street) as you can see in Fig.6. Fig.8 Speed o vehicles in real Fig. Speed o vehicles in proposed Fig.6 Vehicle-vehicle conlict at Toamnei Street Fig.0 Fuel eiciency o vehicles in real Fig.7 Vehicle-pedestrian conlict at Toamnei Street 3 Simulation In the ollowing are presented comparative graphs between the actual and the proposed one: speed o movement, uel consumption, stops/vehicle and delays. Fig. Fuel eiciency in proposed ISSN: ISBN:

5 Proceedings o the 2nd International Conerence on Environmental and Geological Science and Engineering Fig.2 Stops o vehicles in real Fig.5 Delays o vehicles in proposed Delays are caused by conlicts o the pedestrian with vehicles, arising in particular or vehicles that made a right turn onto B-dul Hărmanului rom Toamnei Street. Fig.3 Stops o vehicles in proposed Stops occur in areas where traic lows are intersecting and traic volumes are high. The crossing o traic low generally occurs at the exit or entry into intersection, when most drivers try to get on a lane on which to continue their movement towards the next intersection. Some vehicles will be orced to stop in order to it in lane that they wish to continue their movement. 4. Conclusions Thus the proposed solution relected the results rom the actual regarding: time delays generated by the vehicle stops, uel consumption eiciency, the ormation o queues, reducing the conlict points. Even a doubling o existing traic volumes, has not created large queues. Reerences: [] Florea D., Aplicaţii telematice în sistemele avansate de transport rutier, Editura Universităţii Transilvania din Braşov, ISBN , 2004 [2] Florea D., Coaru C., Soica A., Managementul traicului rutier, Ediţia a II-a, Editura Universităţii Transilvania din Braşov, ISBN , 2004 [3] Transportation Research Board (TRB), Highway Capacity Manual 2000, Washington, DC, National Research Council, 2000 [4] Federal Highway Administration, Signalized intersections: Inormational Guide, U.S. Department o Transportation, 2004 [5] Traicware Ltd., Synchro 6, [6] Traicware Ltd., SimTraic 6, Fig.4 Delays o vehicles in real ISSN: ISBN: