Traffic Signals Using Irc

Abstract As we all know traffic volume is increasing day by day in cities due to growth of industrialization and urbanization of cities. Thus to manage the present traffic volume new methods were adopted to provide better, easy and safe movement of traffic. The traffic conflictions are major on intersections of two roads. Traffic signals is a way to control the traffic at the intersections of the cities and avoid the conflictions of the vehicles at the intersection. Traffic signals also helps the traffic to move with safety and easily, which tends to minimize the collision between the vehicles at the intersection. In this dissertation we surveyed the traffic volume of intersections of the Vidisha city and traffic signals were designed at each intersection . The one part of the thesis is survey of traffic volume,

which

is

done

by

manual

method,

wherein

the

vehicles

are

counted

manually without using any device or sensor with respective vehicle categories like passenger, commercial and agricultural etc. and the other part is design of traffic signals, which is done according to the IRC method of signal design by adopting maximum PCU on the intersection in each direction. The design of traffic signals at these intersections in vidisha will help the growing traffic to move with ease and safety and also helps in reducing the accident rate at the intersections due to congestions and confliction between vehicles. Key words: Vidisha, Controlling Traffic

TABLE OF CONTENTS Serial no.

Title

Page no.

Definitions Chapter 1

Introduction

1.1

Purpose of Traffic Signals

1.2

Intersection Design and its Relationship to Signal Timing

1.3

Objectives of Basic Signal Timing Parameters and Settings

1.3.1

Other Policy Considerations

Chapter 2

Literature Review

Chapter 3

Study Area

Chapter 4

Operational and Safety Analysis

4.1

Characteristics Affecting Signal Timing

4.1.1

Location

4.1.2

Transportation Network Characteristics

4.1.3

Intersection Geometry

4.1.4

User Characteristics

4.2

Basic Operational Principles

Chapter 5

Design of Traffic Signals

5.1

Traffic Study

5.2

Signal Designing Conclusion References

Definitions Accessible Pedestrian Signal: A device that communicates information about pedestrian timing in nonvisual format such as audible tones, verbal messages, and/or vibrating surfaces. Cycle Length: The time required for a complete sequence of signal indications. Conventional Pedestrian Signal: A device that communicates information about pedestrian timing in conventional (i.e., visual) format. Coordinated Traffic Signal System: A system of traffic signals for which a timed relationship exists between adjacent traffic signals within the system. Effective green time: The time during which a given traffic movement or set of movements may proceed; it is equal to the cycle length minus the effective red time. Effective red time: The time during which a given traffic movement or set of movements is directed to stop; it is equal to the cycle length minus the effective green time. Emergency Vehicle Pre-emption: Transfer of normal operation of a traffic signal to a special mode of operation that quickly gives the green phase for the direction of traffic from which the approaching emergency vehicle is arriving.

Lost Time: The portion of time at the beginning of each green period and a portion of each yellow change plus red clearance period that is not usable by vehicles. Major Street: The street normally carrying the higher volume of vehicular traffic at an intersection. Minor Street: The street normally carrying the lower volume of vehicular traffic at an intersection. Peak-hour factor: The hourly volume during the maximum-volume hour of the day divided by four times the peak 15-min flow rate within the peak hour; a measure of traffic demand fluctuation within the peak hour. Pedestrian Indication: A signal head, which contains the symbols WALKING PERSON (symbolizing WALK) and UPRAISED HAND (symbolizing DON'T WALK), that is installed to direct pedestrian traffic at a traffic control signal. Stop line: A pavement marking that indicates where motor vehicles should begin to queue for a red traffic signal indication. Saturation Flow Rate: The equivalent hourly rate at which vehicles can traverse an intersection approach under prevailing conditions, assuming a constant green indication at all time and no loss time, in vehicles per hour or vehicles per hour per lane.

Total lost time: The time per signal cycle during which the intersection is effectively not used by any movement; this occurs during the change and clearance intervals and at the beginning of most phases. Traffic Signal: A device to warn, control, or direct at least one traffic movement at an intersection. Yellow Pedestrian Activated Flasher: Yellow flashing signal that is activated by the pedestrian and which emphasize the location of a crosswalk.

CHAPTER 1 INTRODUCTION

The traffic of our country is growing day by day , by which the control and management of traffic is a major problem. The traffic volume is increasing regularly so controlling heavy traffic is very hard for the traffic police and the accident rate are also increasing at intersections. So to overcome the crises of increasing traffic, design of traffic signals on squares of the cities are necessary. The traffic signal helps the vehicle to move on square or intersections with safety and Ease. Thus the design of traffic signal is an essential part of traffic control in major cities, which tend to economical and safe method for proper operation of vehicles at intersections. Traffic signals are the traffic control measure which is used to control the conflicts between vehicles on squares, where traffic flow intensity is high, mostly in cities. The first traffic signal was fixed in London in 1868 , which was a semaphore- arm type signal. The sections where large number of crossings and right turn traffics are available there are a possibility of several accidents because of non orderly movement of vehicles. In earlier time traffic is controlled by traffic police manually by showing signs to the traffic in each direction but as the traffic volume is growing large and large it is not possible to handle the traffic by one traffic police so as to under come this problem traffic signals has been designed to control the traffic with accuracy and timely. The traffic signals has three lights orderly red, yellow, green, by which the can guide the traffic whether to move or stop. The main purpose or function of traffic signal is to draw attention, provide meaning and time to respond and to have minimum waste of time. The main object of traffic signals is to avoid confliction of vehicles, easy and safe movement of vehicles at intersections. Traffic signal guides the

vehicles

to

move

or

not

by

which

the

confliction

between

vehicles

are

avoided, the signal helps the vehicle to move or stop at intersection according to the direction of movement of vehicle.

1.1 Purpose of Traffic Signals: The Manual on Uniform Traffic Control Devices (MUTCD) defines a traffic control signal as any highway traffic signal by which traffic is alternatively directed to stop and permitted to proceed. Traffic is defined as pedestrians, bicyclists, ridden or herded animals, vehicles, streetcars, and other conveyances either singularly or together while using any highway for purposes of travel. It is with this need to assign the right of way at locations that we consider the dual purpose of traffic signals efficiency and safety which in some cases seem to be conflicting. Safety may be seen as an element needed to be sacrificed in order to achieve improvements in efficiency and meet ever-increasing demands. The reality is that traffic signals can, and in fact must, serve both operational efficiency and safety based on the conditions. The MUTCD goes on to describe that traffic control signals can be ill-designed, ineffectively placed, improperly operated, or poorly maintained, with resulting outcomes of excessive delay, disobedience of the indication, avoidance, and increases in the frequency of collisions. A traffic signal that is properly designed and timed can be expected to provide one or more of the following benefits: 1. Provide for the orderly and efficient movement of people. 2. Effectively maximize the volume movements served at the intersection. 3. Reduce the frequency and severity of certain types of crashes. 4. Provide appropriate levels of accessibility for pedestrians and side street traffic. The degree to which these benefits are realized is based partly on the design and partly on the need for a signal. A poorly designed signal timing plan or an unneeded signal may make the intersection less efficient, less safe, or both. 1.2 Intersection Design and its Relationship to Signal Timing The design of the intersection has a direct influence on its safety and operation from a design and user-ability perspective. Design elements that are particularly relevant include the

number of lanes provided on each approach and for each movement, whether there are shared thru-and-turn lanes, the length of turn bays, the turning radii (especially important for pedestrians), the presence of additional through lanes in the vicinity of the intersection, the size and location of detectors, and presence or absence of left-turn phasing. Other geometric features, like additional through or turn lanes, can also have a significant positive impact on intersection capacity, provided that they are sufficiently long. The other aspect of intersection design is the perception and reaction of the end users. Various decisions need to be made as a user approaches the intersection, which makes it important to simplify the decision making process. 1.3 Objectives of Basic Signal Timing Parameters and Settings A primary objective of signal timing settings is to move people through an intersection safely and efficiently. Achieving this objective requires a plan that allocates right-of-way to the various users. This plan should accommodate fluctuations in demand over the course of each day, week,and year. 1.3.1Other Policy Considerations Additional policy issues that are more detail oriented include: • The maximum allowable cycle length; • Whether the agency will allow lagging and leading left turns by intersection or variable by time of day; • Whether the agency will allow the skipping of left turn phases under low volume conditions; • Whether maximum green times will operate within the coordination plan; • Whether transit preferential policies such as transit signal priority will be implemented aggressively; • The number of signal timing plans (time of day plans) in operation per day to respond to fluctuating traffic demand; • Will coordination timing plans allow intersections to temporarily leave coordination to accomplish tasks (i.e. serve pedestrian calls); and

• Whether coordination patterns will be selected by time-of-day or by real-time traffic data.

CHAPTER 2 LITERATURE REVIEW 

TRAFFIC SIGNAL DESIGN MANUAL

City of Tucson Department of Transportation Traffic Engineering Division This first edition of the City of Tucson Traffic Signal Design Manual expands upon existing guidelines to more completely identify guidelines, practices, and standards for the design of City of Tucson traffic signals. Roadway lighting requirements are addressed only to the extent that intersection lighting is provided at signalized intersections. The purpose of this manual is to provide a consistent set of guidelines, practices, and standards for use by designers, contractors, and

City

of

Tucson

Department

of

Transportation

Traffic

Engineering

Division

(COT/DOT/TED) staff. This manual supplements the 2000 edition and subsequent updates of the Manual on Uniform Traffic Control Devices (MUTCD). It should be used in conjunction with the 1994 edition of the Pima County/City of Tucson Standard Specifications for Public Improvements, and the Pima County/City of Tucson Standard Details for Public Improvements. 

TRAFFIC VOLUME COUNTS

Traffic volume studies are conducted to determine the number, movements, and classifications of roadway vehicles at a given location. These data can help identify critical flow time periods, determine the influence of large vehicles or pedestrians on vehicular traffic flow, or document traffic volume trends. The length of the sampling period depends on the type of count being taken and the intended use of the data recorded.

CHAPTER 3 STUDY AREA

LATITUDE AND LONGITUDE: Suchitra Bus Stop Latitude is: 17.499527 Suchitra Bus Stop Longitude is: 78.47673989999998

CHAPER 4

OPERATIONAL AND SAFETY ANALYSIS The purpose of this chapter is to summarize some of the common techniques used to assess the operational and safety performance of signal timing. The chapter begins by presenting an overview of the characteristics that affect signal timing, including both system and user characteristics. It then presents discussions of operational and safety performance measures and techniques to evaluate those performance measures. Finally, the chapter presents a discussion of signal warrants as presented in the Manual on Uniform Traffic Control Devices and how those warrants relate to signal timing

4.1CHARACTERISTICS AFFECTING SIGNAL TIMING Several overall features affect implementation of signal timing including: • Location • Transportation network characteristics • Intersection geometry • User characteristics The following sections further describe many characteristics and dynamic nature influencing signal timing. 4.1.1 Location One of the primary factors affecting overall signal timing is the environment in which the intersection or intersections being timed are located. Urban environments are frequently characterized by lower speeds and higher degrees of congestion. In addition, urban environments are frequently characterized by higher pedestrian, cyclist, and transit use that often require priority in consideration. Rural environments, on the other hand, are typically higher speed but with lower levels of traffic volumes and fewer, if any, pedestrians, cyclists, and transit vehicles. As a result, signal timing for rural environments is typically dominated by efforts to safely manage high speed approaches; capacity is seldom a constraint. Suburban environments often present a challenging mix of these characteristics. Suburban environments are often characterized by high speeds during the off-peak periods and capacity-constrained conditions during the peak periods. This requires a careful consideration and balance of both safety aspects and operational efficiency. 4.1.2 Transportation Network Characteristics

The configuration of the transportation network under consideration can have a significant impact on the way its traffic signals are timed. Isolated intersections can be timed without the explicit consideration of other traffic signals, allowing the flexibility to either set or target cycle lengths that are optimal for the individual intersection. In these cases, good detection design often yields measurable operational and safety benefits. 4.1.3 Intersection Geometry The overall geometry of an intersection determines its ability to efficiently and safely serve user demand. Pedestrians are often crossing lanes of traffic, whereas transit, bicycles, and vehicular traffic are using the travel lanes provided at the intersection. The number of lanes provided for each approach has a significant impact on the capacity of the intersection and, therefore, the ability for signal timing to efficiently serve demand. For example, a movement served by two lanes rather than one has a higher capacity and thus requires less green time to serve demand. However, increasing the number of lanes on a particular leg of the intersection also increases the minimum pedestrian crossing time across that leg, which by increasing clearance times will offset some of the increase in capacity. 4.1.4 User Characteristics User characteristics clearly influence the effectiveness of signal timing and should be accounted for early in the planning and analysis process. Some of the important factors include the following: • Mix of users: The mix of users at an intersection has a significant influence on signal timing.

Pedestrians

with

slower

walking

speeds,

persons

using

wheelchairs,

and

pedestrians with visual impairments need more time to cross the street; pedestrian walk times and clearance intervals need to be adjusted accordingly. High bicycle use 3-4 may benefit from special bicycle detection and associated bicycle minimum green timing. Emergency vehicle and/or transit use may justify the use of preemption and/or priority. Truck traffic requires accounting for reduced performance (longer acceleration and deceleration times) and larger size of heavy vehicles.

• User demand versus measured volume:

Traffic demand represents the arrival pattern of vehicles at an intersection (or the system, if one considers a group of intersections together), while traffic volume is the measured departure rate from the intersection. If more vehicles arrive for a movement than can be served, the movement is considered to be operating over capacity (oversaturated). However, unless the analyst has measured demand arriving at the intersection through either queue observation or through measurement of departure rates from an upstream under saturated intersection, the true demand at an intersection may be unknown. This can cause problems when developing signal timing plans for a given intersection, as one may add time to a given movement, only to have it used up by the latent demand for that movement. Traffic volume at an intersection may also be less than the traffic demand due to an overcapacity condition at an upstream signal that “starves” demand at the subject intersection. These effects are often best analyzed using micro simulation.

4.2Basic Operational Principles The basic operation of vehicular movement through a signalized intersection is presented in Figure 3-2 below. The signal display is presented on the horizontal axis, the instantaneous flow of vehicles on the vertical axis. During the time while the movement is receiving a red indication, vehicles arrive and form a queue, and there is no flow. Upon receiving a green indication, it takes a few seconds for the driver of the first vehicle to recognize that the signal has turned green and to get the vehicle in motion. The next few vehicles also take some time to accelerate. This is defined as the start-up lost time or start-up delay and is commonly assumed to be approximately 2 seconds. After approximately the fourth vehicle in the queue, the flow rate tends to stabilize at the maximum flow rate that the conditions will allow, known as the saturation flow rate. This is generally sustained until the last vehicle in the queue departs the intersection. Upon termination of the green indication, some vehicles continue to pass through the intersection during the yellow change interval; this is known as yellow extension. The usable amount of green time, that is, the duration of time between the end of the start-up delay and the end of the yellow extension, is referred to as the effective green time for the movement. The unused portion of the yellow change interval and red clearance interval is called clearance lost time.

CHAPTER 5 DESIGN OF TRAFFIC SIGNALS The designing of traffic signals has two phases. The phases are listed below:  

TRAFFIC STUDY SIGNALS DESIGNING

Traffic signals can be designed using two methods. They are IRC method Webster method

 

TIW

DS

E

RE

I

ACB G

I

I

FS N

CTR

F

I

I

DH G YO N I

G L

S I

G

A

A S

N

F

S E

D

G

C

HD

UT

N

F S

TDE

N

R IL

SNOM

G O

FMT A T E

S

5.1 Traffic study Using count period to determine study method Two methods are available for conducting traffic volume counts: (1) manual and (2) automatic Manual counts are typically used to gather data for determination of vehicle classification, turning movements, direction of travel, pedestrian movements, or vehicle occupancy. Automatic counts are typically used to gather data for determination of vehicle hourly patterns, daily or seasonal variations and growth trends, or annual traffic estimates. The selection of study method should be determined using the count period. The count period should be representative of the time of day, day of month, and month of year for the study area. The study methods for short duration counts are described in this chapter in order from least expensive (manual) to most expensive (automatic), assuming the user is starting with no equipment. Manual count method: Most applications of manual counts require small samples of data at any given location. Manual counts are sometimes used when the effort and expense of automated equipment are not justified. Manual counts are necessary when automatic equipment is not available. Manual counts are typically used for periods of less than a day. Normal intervals for a manual count are 5,10, or 15 minutes. Traffic counts during a Monday morning rush hour and a Friday evening rush hour may show exceptionally high volumes and are not normally used in analysis; therefore, counts

are

usually

conducted

on

a

Tuesday,

Wednesday,

or

Thursday.

Manual Count Recording Methods: Manual counts are recorded using one of three methods: tally sheets, mechanical counting boards, or electronic counting boards.

5.2 SIGNAL DESIGNING: IRC method 

The pedestrian green time required for the major and minor roads are calculated based on



walking speed of 1.2 m/sec. and initial walking time of 7.0 secs. These are the minimum green time required for the vehicular traffic on the minor and



major roads respectively. The green time required for the vehicular traffic on the major road is increased in the

 

proportion to the traffic on the two approach roads. The cycle time is calculated after allowing amber time of 2.0 secs each The minimum green time required for clearing vehicles arriving during a cycle is a determined for each lane of the approach road assuming that the first vehicle will take 6.0 secs. And th subsequent vehicles (PCU) of the queue will be cleared at a rate of 2.0



secs.

The

minimum

green

time

required

for

the

vehicular

traffic

on any of the approaches is limited to 16 secs. The optimum signal cycle time is calculated using Webster’s formula The saturation flow values may be assumed as 1850,1890,1950,2250,2550and 2990 PCU per hour for the approach roadway widths (keb to median or centerline) of 3.0,3.5,4.0,4.5,5.0 and 5.5m; for width above 5.5m, the saturation flow may be assumed as 525 PCU per hour per meter width. The lost time is calculated from the amber time, inter-green time



and the initial delay of 4.0 secs. For the first vehicle, on each leg. The signal cycle time and the phases may be revised keeping in view the green time required for clearing the vehicles and the optimum cycle length determined in steps (iv) and(v) above.

SIGNAL DESIGN OF INTERSECTION: Design traffic on road 1 = 1471/2=736 PCU/hour Design traffic on road 2 = 392 PCU/hour Width of road 1 = 10m Width of road 2 = 9.5m 1) Pedestrian green signal time for road 1 10 +7 = 1.2

= 15.33 sec. Pedestrian green signal time for road 2 9.5 +7 = 1.2

= 14.91 sec. 2) Green signal time for vehicles on road 2, G2 = 15.33 sec Green signal time for road 1, 736 G1 = 15.33 X 392 = 28.78 sec 3) Adding 2.0 sec each to the clearance amber and 2.0 sec to the inter-green period for each phase Total cycle time required = (2+15.33+2)+(2+28.78+2) = 50.11 sec Signal cycle time may be conveniently made in multiple of 5 sec. So the cycle time will be 55 sec. The extra 2.5 sec. per cycle may be assigned to the green time of road 1 and 2 as 1.5 and 1.0 sec. respectively. G1 = 28.78 + 1.5 = 30.28 ≈ 31 sec. G2 = 15.33 + 1.0 = 16.33 ≈ 16 sec.

4) Vehicles arrivals per lane cycle on road 1 736 = 55 = 13.38 PCU Minimum green time for clearing vehicles on the road 1= 6 + (13.38-1) 2 = 30.76 sec. Vehicles arrivals per lane cycle on road 2 392 = 55 = 7.12 PCU Minimum green time for clearing vehicles on the road 2= 6 + (7.12-1) 2 = 18.25 sec. As the green time designed above for two roads by pedestrian crossing criteria are having values high, thus the above values can be accepted as they are alright and minimum. 5) Total lost time per cycle = (amber time + inter-green time + time lost for initial delay of first vehicle) For two phase = (2+2+4)X 2 = 16 sec. From IRC: 93-1985 The total lost

time

per

cycle

is

equal

to

the

total

amber time per cycle i.e. 8 sec, plus 4 sec. reaction time for first vehicle in phase 1, plus 4 sec reaction time for first vehicle in phase 2, i.e. equal to total 16 sec. Saturation flow = 525 X W PCU per hour Where, W = width of the approach measured from kerb to the inside of the central median or mentioned centre line of the approach.

The width lesser from 5.5 m, the values for saturation flow is taken from the table below:

Saturation flow for critical approach for road 1 = 2550 +

40∗5 5

= 2590 PCU/hour

Saturation flow for critical approach for road 2 = 2250 +

40∗4.75 5

= 2288 PCU/hour

736 y1 = 2590 = 0.28

392 y2 = 2288 = 0.17 Y = y1 + y2 Y= 0.28 + 0.17 Y = 0.45 The Webster’s formula for optimum cycle time 1.5 L+5 C o = 1−Y Where, Co = optimum cycle length in seconds L = total lost time per cycle Y = volume/ saturation flow for critical approach in each phase. 1.5 L+5 Co = 1−Y Co =

1.5∗16+5 1−0.45

29 Co = 0.61 Co = 52.72 sec Thus the total cycle time of 55 sec is acceptable.

CONCLUSION By studying the road traffic of the city we analyzed that the major accident cause is collision of vehicles at the intersections. The collision may be rear shunt on approach to junction, right angled collision, principle right turn collisions and pedestrian collision. These collisions can be avoided if proper design of signal is done at the intersection so that the main objective of the dissertation is to provide better and safe movement of traffic through signal design at

the intersection of the Vidisha city is satisfied. The signal is designed as per IRC guidelines so that the signal can justify the proper movement of the traffic. The effect of the signal design can be seen in reduction of accident cause by which the reduction in fatal injuries at the intersection. Thus provide a better and safe movement of the traffic. The signal design can also helps the pedestrian to cross the road safely. The signal timing plays an important role in traffic movement. Thus the timing of the signal should be such that it does not cause delay to the vehicles. If the timing is causing extra delay to the vehicles than the driver will disobey the signal, resulting in cause of accident. Thus the signal timing should justify the movement of vehicles so that extra delay by the RED signal will not affect the total journey time.

REFERENCES

[1] IRC-93:1985 “Guideline on Design and Installation of Road Traffic Signals”. [2] Justo Khanna New age Publication. [3] L.R. Kadiyali khanna publications. [4] Road accident in India Government of India Ministry of Road Transport And Highways Transport Research Wing New Delhi 2010. [5] Federal Highway Administration (1996). Traffic Control Systems Handbook. Report No. FHWA-SA-95-032, U.S Department of Transportation, Washington DC [6]2007 National Traffic Signal Report Card Technical Report, National Transportation Operations Coalition. [7]USDOT. Nationwide Personal Transportation Survey, http://nhts.ornl.gov.2001/index.shtml, 2001.