Its Evaluation

ITS IMPLEMENTATION AND EVALUATION By P.S.SURESH (Manager. T. E. CMS Traffic systems Limited, W 324, M.I.D.C. Rabale Navi Mumbai, 400 701) & C.KRISHNA KUMAR (General Manger, CMS Traffic systems Limited, W 324, M.I.D.C. Rabale Navi Mumbai, 400 701) 1. INTRODUCTION Intelligent transportation systems (ITS) represent the application of information processing, communications technologies, advanced control strategies, and electronics to the field of transportation. Information technology has progressed from the transmission of a few bytes per second to billions of bytes per second. The spectacular increase in performance and the almost as spectacular reduction in real costs of both computing and communication technologies have enabled engineers to address traffic congestion problems also and to make transport operations more efficient. Elements of what came to be known as ITS has been incrementally deployed in many localities over the years. Traffic signal systems are a prevalent feature of the transportation system in both large and small urban areas. Real time area traffic control systems (ATC) or adaptive traffic control systems attempt to develop a suite of adaptive control strategies that are able to respond to recurrent congestion, isolated demand spikes, extensive over saturation and incident and accident conditions on both arterial and grid networks. The principal components of ATC include signal controllers, traffic detectors, and controller interconnection and centralized system supervision. These are of cyclic and acyclic types. Cyclic systems are based on cycle lengths and splits. Acyclic systems do not depend on cycle lengths. Acyclic systems give better performance when working independently. Number of cities in developing countries have started the implementation of ATC as part of intra urban ITS. ATC are developed for the homogeneous traffic conditions prevalent in cities of developed countries whereas heterogeneity is the characteristic of traffic in cities of developing countries. This paper describes the implementation of ATC system in Delhi, the capital city of India. The paper further assesses the evaluation of the system. Delhi is beset with the problems of heterogeneous traffic. Non-motorized and slow moving vehicles constitute a sizeable chunk of vehicles here. 2. IMPLEMENTATION OF ATC Cyclic system of Split, Cycle and Offset Optimisation Technique (SCOOT) developed by TRL U.K has been selected for installation in Delhi. SCOOT system has been installed in approximately 170 installations across the world including cities in developing countries having heterogeneous traffic. SCOOT continuously measures traffic volumes on all approaches to intersections in the network and changes the signal timings to minimize a Performance Index (PI). This PI is a composite measure of delay, queue length and stops in the network. These changes in signal timings are made such that they are small enough to avoid major disruptions in traffic flow, but are frequent enough to allow rapid response to changing traffic conditions. SCOOT, similar to the TRAffic Network StudY Tool (TRANSYT)

[Robertson (1969)] is a model-based system that enables it to generate a Cyclic Flow Profile (CFP) based on the actual field demand. The fundamental unit of demand in SCOOT is a Link Profile Unit, which is a hybrid measure of the flow and occupancy data received from the detectors. Based on the generated CFP, SCOOT then projects platoons movement and dispersion at the downstream intersection. This helps it to model queue formation and queue discharge. SCOOT is installed on a central computer and houses three optimizers: one for cycle time, one for green splits, and one for offsets. The cycle time optimizer computes an optimum cycle length for the critical intersection in the network. The split optimizer then assigns green splits for each intersection based on this cycle length and the offset optimizer calculates offsets. These parameters are recalculated and implemented every second and changes are made if required. As accurate prediction and discharge of queues is pivotal to SCOOT’s performance, validation of the field parameters, such as link journey time, maximum queue clear time and queue discharge rate is of utmost importance. Several agencies have carried out SCOOT evaluations comparing its performance to previously existing signal control strategies. Benefits realized from SCOOT depend on the prior control strategy and how well it had been optimized. ATC for Delhi was planned for implementation in phases. This paper details about the pilot phase of 46 intersections. Delhi has a radial pattern of road network with Connaught Place as the hub of commercial activities. Nine junctions of Connaught Place and its outer circle are covered in the pilot phase of 46 intersections in the ATC. Connaught Place area has got one-way traffic. Eight junctions on Mathura Road, a major arterial connecting south Dehi and Central, North Delhi were selected so that utility of ATC on a more representative traffic arterial can be ascertained. Heavy goods vehicle traffic is banned in central Delhi area. However, these vehicles movements are allowed in part of the outer ring road area junctions under ATC. Even though nonmotorised vehicles are not allowed in New Delhi area, junctions in old Delhi area with prevalence of non-motorized traffic are also covered in the ATC so that its effect on ATC can be assessed. Panchkuian Road, a major arterial from central Delhi to North and West Delhi beset with street parking has also been included in the ATC area. Two pairs of multiplexed leased telephone lines were selected for communication. The ATC control room is located at Traffic police office in Traffic police lines, Teen Murti. ATC system hardware consists of a DEC Alpha server central computer. This central computer is linked to Graphical User Interface (GUI) terminals, printers, projectors etc.. The drawbacks of ATC are that they are detector demanding. ATC need real-time detector data. The decision to implement ATC has to be matched by a commitment to maintain the expanded detector system. Much like an actuated signal control, if detectors fail, then the benefits of ATC are eliminated as they revert to a fixed-time effectiveness. 2.1 LIMITATIONS: Implementation of ATC in developing countries is having its own associated problems. In Delhi, many functions of the ATC have not been utilized fully, to the contrary some times the advantages were negated by manual intervention. Often, the manual mode operation at the intersections to facilitate the green wave movement along a corridor was made without opting for facility of green movement in the system. This has resulted in excessive delays and queues as the traffic was disrupted suddenly.

Poor communication facilities between the intersection controllers to the central control room have put the intersections on isolated mode, further impeding effective control. One of the pre-requisite for the smooth functioning of the ATC system is un-interrupted power supply at all the related junctions. In case of power supply failure the junction starts functioning as an isolated junction and cease to be part of the ATC system. The following system related features which are part of SCOOT based Real Time Area Traffic Control System are to be put into use to tap advantages of system fully. 1. Variable Message Sign (VMS). 2. Green-wave facility for the VIP movement. 3. Bus Priority System for the important corridors. 3. EVALUATION OF ATC 3.1 CRITERION FOR EVALUATION The TEA-21 ITS Evaluation Guidelines suggests that the evaluation of ITS projects should encompass five major goals. Also, several related measures have been identified as useful to capture the impacts of ITS projects. Table 1 details the goal areas and key measures with explanations for evaluating ITS projects. TABLE 1. EVALUATION GOALS AND MEASURES Goal Area Safety

Mobility Efficiency Productivity Energy and Environment

Measures Reduction in the overall rate of crashes Reduction in the rate of crashes resulting in fatalities Reduction in the rate of crashes resulting in injuries Reduction in travel time delay Reduction in travel time variability Improvement in customer satisfaction Increases in freeway and arterial throughput Cost savings Decrease in emission levels Decrease in energy consumption

(Source: http://www.its.dot.gov/eval/ResourceGuide/EvalGuidelines, Transportation Equity Act For The 21st Century; Guidelines For The Evaluation Of Operational Tests And Deployment Projects For Intelligent Transportation Systems (ITS)) 3.2 DETAILS OF EVALUATION 3.2.1 SAFETY Data on accidents and fatal accidents were collected from the ATC area as well as for Delhi for the years of 1999 and 2001. The total number of accidents have decreased by 4% in ATC as well as non-ATC areas of New Delhi and Central Delhi Districts over the period from 1999 to 2001.The percentage decrease in fatal accidents is higher in ATC area in comparison of non-ATC area in New Delhi and Central Districts. However the number of fatal accidents have declined by 19% in ATC area and just 5% in non-ATC area over the similar time period.

3.2.2 MOBILITY Traffic flow variables like speed, delay, volume etc. were collected for the evaluation on mobility. The data for the “before” study was collected in July 1999 and for the “after” study in February 2002. The following surveys were done for the evaluation of the ATC Classified directional traffic volume The turning counts, volume counts and link counts of different categories of vehicles, eleven in this case, for the ‘before’ and ‘after’ studies were made. Moving observer surveys At the time of the ‘before’ study, a lengthy reconnaissance was made to select the routes for the moving observer observations. Eight routes were identified for estimation of journey speed with moving observer method before and after the implementation of ATC. Macro Impacts: There has been an increase in the flow and improvements in delay and journey time due to the implementation of ATC. That is to say, that whilst flows have increased, ATC has managed to ‘release’ capacity and time so that this increased volume passes through the network slightly better than the lower volume passed through essentially the same network prior to ATC implementation. The delay per km has reduced from 50.8 seconds to 39.7 % showing a reduction of 21.7 % in whole network. Journey time has reduced from 165.6seconds to 157.5 seconds. Average speed in ATC area has increased to 22.86 km/hour showing 5.2 % increase. Micro Impacts: A great deal of information was collected for nearly all junctions in the ATC area. This includes directional volume of various categories of vehicles, as many as eleven in this case. Individual junctions were studied for different times of day continuous from 08.00 hours to 21.00 hours. The following observations are made regarding at the micro level. 1.The growth of traffic at the major junction on the Ring Road has been around 15% per annum 2. The traffic volume in and around Connaught Place has increased at a rate of between 9 and 11% annually 3. Most of the junctions in the ATC controlled area now have extended peak hours, both morning and evening, compared to the time of the ’before’ study, and most of the link volumes have also grown at the rate of about 10% annually in line with the increase in volume experience by the junctions. Journey time have reduced in seven out of the eight routes selected for the study. It was found that there is a maximum reduction in travel time of 9.86%. Maximum delay in reduction was 45.85 %. The average traffic flows along all selected routes have increased. Maximum increase of 37.6 % traffic flow was recorded in two routes. Among these one route has recorded reduction in delay and travel time, while the other has shown increase in delay and journey speed. 3.2.3 EFFICIENCY Vehicles-km per hour in the ATC network was used for comparing the throughput. It was found that the vehicle through put has increased to 133,734 veh-km/hr. from 107,191 veh-km /hr with the installation of ATC. This shows an increase of 24.8 %. It

has to be noted that the accrued benefits like reduction in delay and increase in travel speed have taken place with this increased throughput. 3.2.4 PRODUCTIVITY Cost savings from travel time savings were worked out. The total passenger hour loss has been converted into monetary terms as the value of time for the road users for various vehicular modes is different. The value of time has been considered separately for Private, Public and Intermediate Public Transport (IPT) modes. The value of time for work and non-work trips also differ and the same has been taken into account by segregating the total trips in to these two categories. It is estimated that ATC has resulted in travel time saving of Rs. 3,61,68,400.00 per annum. However for the financial evaluation of ATC the travel timesavings have not been considered. 3.2.5 ENERGY AND ENVIRONMENT Reduction in delay and stops have lead to savings in fuel consumption of vehicles in the ATC area. The savings in fuel consumption due to reduction in delay for day considering average 9 Hrs. of signal operation was found out. . This saving translates to be around Rs.6,82,56,000 per annum by considering 200 working days in a year. The amount has been further halved in order to offset the effect of excise and other govt. levies on the petroleum & lubricants. Therefore the effective savings on this account comes out to be Rs. 3,41,28,000. 3.2.6 ECONOMICAL EVALUATION It was found that the project of installation of ATC has an Internal Rate of Return (IRR) of 72 % for an analysis period of five years. Savings in fuel consumption due to reduction in delay in the ATC area was the only benefit considered in the evaluation. Other benefits like savings in travel time, savings due to reduction in accidents, environmental benefits etc. were not considered. Sensitivity analysis of benefits and costs variation was also done. It was found that with a 10 % increase in cost of maintenance and 10 % reduction in estimated benefits the IRR is 46 %. IRR with 20 % variation in maintenance costs and benefits are found to be 32 %. This amply makes clear the fact that installation of ATC projects are economically viable in cities of developing countries 4.CONCLUSION Intelligent transportation systems (ITS) represent the application of information processing, communications technologies, advanced control strategies, and electronics to the field of transportation. ATC can be the hub of traffic management incorporating advanced electronics along with other ITS activities. This paper deals with the implementation and evaluation of real time ATC implemented in Delhi, the capital city of India. ATC here is planned in phases, pilot phase of 46 intersections being the theme of study. This area is a representative sample of the prevailing traffic conditions in cities of developing countries, heterogeneity in speed along with lack of lane discipline being the characteristics. The full potential of the system is yet to be explored, many often it was found that manual interventions have resulted in negating the benefits of the system. Safety, mobility, efficiency, productivity and energy and Environment are selected as the criterion for evaluation of ATC. It was found that the safety in the ATC area improved over the past three years by way of reduction in number of fatal accidents. Delays along selected routes have reduced due to the implementation of ATC. It was found that there are cost savings by way of reduction in travel time and fuel consumption of vehicles. The

throughput through the ATC area has improved. The evaluation of ATC project done as a part of this study has found that this project is having an IRR value of 72 % for an analysis period of 5 years. 5. REFERENCES Robertson, D.I. 1969. TRANSYT: A traffic network study tool. Laboratory Report 1014. Transport and Road Research Lab, Crow Thorne, Berkshire, U.K.