Introduction
Unlike many other fields of engineering, situations that are interesting for operations to an engineer cannot be reproduced in a laboratory. Hence current traffic characteristics can only be collected after performing an entire field inspection. There are several methods of data acquisition collection depending on the requirement of the study.
Traffic Parameters
The most important traffic characteristics to be collected from the field include speed, travel time, flow rate and density. In certain cases, spacing and progress are measured directly. Also, occupancy, i.e. the percentage of time a road space is occupied by vehicles, is also of importance.
Traffic Volume Data Collection And Presentation
The measurement procedures can be broadly divided into five based on the geographical scope of the survey categories:
- Measurement at a point on the road
- Measurement on a short section of the road (less than 500 meters)
- Measuring along the length of the road (more than about 500 meters)
- Extensive samples obtained from many locations and
- The use of an observer moving in a traffic stream.
1. Single Point Measurement
The most important point measurement is the vehicle volume number. Data can be collected manually or automatically. In the manual method, the observer stands at the point of interest and counts vehicles using manual counting. Normally data will be collected for a short interval of 5 minutes or 15 minutes etc. and for each type of vehicular traffic like cars, two wheelers, three wheelers, LCVs, HCVs, multi-axle trucks, non-motorized traffic such as bullock carts, hand-carts, etc. From flowdata, flow and progress can be derived.
Modern methods include the use of an induction loop detector, a video camera and other types of technology. These methods help to collect accurate information over a long period of time. In the video, cameras, data is collected from the field and then analyzed in the laboratory to obtain results. Radars and microwave detectors are used to obtain the speed of the vehicle at a certain point. Because there is no length, density cannot be obtained by measuring at a point.
2. Measurement On a Short Section
The main idea of this study is to determine the instantaneous speed of vehicles. Manual methods include use of an Enoscope. With this method, the length of the base is marked on the road (30-90 meters).
The enoscope is placed at one end and the observer will stand at the other end. He sees the vehicle passing from the far end through the Enoscope and initiates the stopwatch. Then the observer switches off the stopwatch when a vehicle passes in front of him.
An alternative method is to use a pressure contact tube that provides a pressure signal when the vehicle moves at both ends. The next most frequently used method is the induction loop detector which works on the principle of magnetic inductance. The road will be cut and a small magnetic loop placed. When the metal content in the vehicle passes, a signal and count will be generated of the vehicle automatically. The advantage of this detector is that counts can be obtained all through the life of the road. However, the probability of errors is possible due to noisy signals which may arise as a result of heavy vehicles passing in adjacent lanes.
3. Measurement Over a Long Section
This is commonly used to obtain changes in speed over a section of road. Usually, that particular section of road will have a length of over 500m. The density can also be found. The most conventional method is being Aerial Photography Method. Density can be measured from a single image, but not velocity or volume. In time-lapse photography, several images are available.
Road Markings
The basic purpose of road markings is to direct and control traffic on the highway. They are very important to ensure safe, smooth and harmonious traffic flow. Different types of traffic markings such as longitudinal markings, transverse markings, object markings and special markings warn the drivers of dangerous places on the road, etc.
1) Transverse markings
Transverse markings are marked across the direction of traffic. They are marked at intersections etc. The type of road marking for a specific intersection depends on the speed characteristics of the traffic, availability of space etc. Line stop markings, pedestrian crossing markings, directional arrows etc. are some of the markings on approaches to intersections.
2) Warning lines
Warning lines warn the driver of obstacles. They are marked on horizontal and vertical turns where the visibility is greater than the prohibition criteria established for no overtaking zone. They are dashed lines with a length of 6 m and a gap of 3 m.
Classification Of Road Markings
Road markings are defined as lines, patterns, words or other devices, other than signs, embedded into, applied or attached to the road or kerbs or to objects on or near the road, to control, warn, guide and inform users.
Longitudinal Markings
Longitudinal markings are placed along the direction of traffic on the road surface. They are available to separate the traffic stream in the same direction and the predominant color is white. The yellow color is used to separate the opposite traffic flow direction and also to separate the pavement edges. The lines can be either dashed, solid or double solid. Different types of longitudinal markings are centreline, traffic lanes, no passing zone, warning lines, boundary or edge lines, bus lane markings, cycle lane markings. The center line separates opposing traffic streams and facilitates their movement.
Centre Line
The centre line separates opposing traffic streams and facilitates their movement. Usually, no centre line is intended for roads with a width of less than 5 m and for roads with more than four lanes. The centre line can be indicated by a single dashed line, a single solid line, a double dashed line, or a double solid line depending on road traffic requirements. The broken lines are placed with 4.5m gaps and on curves and intersections it is reduced to 3m.
Traffic Lane Lines
It helps to divide wide roads into separate lanes on both sides of the road and also helps the driver to drive straight and also limits the meandering tendency. These markings help to increase the capacity of the road and also ensure greater safety. Traffic lane lines are usually simple dashed lines of 100 mm in width.
No Passing Zones
No passing zones are established on apex curves, horizontal curves and two and three-lane highways where overtaking is prohibited due to the low sight distance. It can be indicated by a solid yellow line along the centre or a double yellow line. These solid lines are also called barrier lines. When the solid line is to the right of the dashed line, the passage restriction applies only to the opposing traffic.
Warning Lines
Warning lines warn drivers of approaching obstacles. They are marked on vertical and horizontal curves where visibility is greater than the prohibition criteria envisaged for no overtaking areas. They are broken lines with 6m in length and 3m of empty space. A minimum of seven line segments should be provided.
Edge Lines
The boundary lines indicate the edges of rural roads that do not have curbs to delineate the limits up to which the driver can venture out safely. They should be at least 150mm from the actual edge of the pavement. They are painted white or yellow. All lines should preferably be light reflective so that they are visible even at night. Better nighttime visibility can also be achieved through the use of tiny glass beads embedded in the pavement marking materials to produce a reflective restoration surface.
Cross Marks
Cross signs are marked along the direction of travel. They are marked at intersections etc. The conditions of the site play a very important role. The type of road markings for a particular intersection depends on several variables such as traffic speed characteristics, availability of space etc. The horizontal signs of the stop line, the signs for pedestrian crossings, direction arrows, etc. are just some of them the signs on the accesses to the intersections.
Stop Lines
The top line indicates the position beyond which vehicles must not proceed when it is necessary to stop from control devices such as signals or from the traffic police. They should be placed parallel to the carriageways intersecting or at right angles to the direction of approaching vehicles.
Pedestrian Crossings
Pedestrian crossings are foreseen in the places of conflict between vehicular and pedestrian traffic. The site should be selected so that there is less discomfort for pedestrians and even there is no much interruption of the vehicles. At intersections there should be pedestrian crossings preceded by a stop line at a distance of 2-3 m for unmarked intersections and at a distance of one meter for marked intersections. The most commonly used model for pedestrian crossings is Zebra intersection consisting of equally spaced white stripes of 500 mm wide.
Directional Arrows
In addition to the warning lines on approach lanes, directional arrows should be used as a guide to drivers ahead of time on the correct lane to take as they approach busy intersections. Due to the low angle at which the signs are seen by drivers, the arrows should be extended in the direction of travel for adequate visibility. The dimensions of these arrows are also very important.
Marking Of Objects
Physical obstacles in a carriageway such as the central reservation or obstacles near the carriageway such as signal poles, piers, etc. constitute a serious danger to the flow of traffic and must be properly marked. They can be marked on objects adjacent to the roadway.
Objects Adjacent To Carriageway
Sometimes objects adjacent to the carriageway can obstruct the flow of traffic. Items such as subway piers and abutments, culvert headwalls etc. are some examples of such obstructions. They should be marked with alternating black and white stripes at a forward angle of 45 with respect to the direction of traffic. Polls near the carriageway should be painted alternately in black and white up to a height of 1.25m above street level. Other items such as guard stones, drums, guardrails etc. where the chances of vehicles hitting them only when the vehicle runs out the roadway should be painted solid white. Curbs of all islands located in the traffic flow line must be painted with alternating black and white stripes of 500 mm wide or black and red white stripes of the same width.
Word Messages
Information to guide, regulate or warn the road user can also be transmitted by registration of word messages on the road surface. The characters for word messages are usually uppercase letters. The legends should be as short as possible and should not consist of more than three words for each message. Word messages take more time and time to read and understand than other avenues signs. Therefore, usually only a few important ones are adopted. Some of the examples of the word messages are STOP, SLOW, SCHOOL, RIGHT TURN ONLY etc.
Traffic Signs
Road signs inform about the condition of the road ahead, provide directions to follow at major intersections or junctions, warn or guide drivers and ensure the proper functioning of road traffic. These signs act as traffic control devices and are a medium for communication between traffic engineers and road users. Unlike other modes of transport, there is no control over drivers using the road. This is where traffic control devices come to the rescue of the traffic engineer.
Requirements For Traffic Control Equipment
- The control device should meet the need: Each device must have a specific purpose for the safe and efficient operation of the traffic stream.
- It should attract the attention of road users: This affects the design of signs. Proper visibility should be ensured to gain attention. The labelling should also be prominent and clear. The sign should be properly placed so that the driver does not require any special effort to see the sign.
- It should convey a clear, simple meaning: Clarity and simplicity of the message are essential for the driver to understand the meaning correctly in a short time. In this regard, the use of colour, shape and legend as codes become important. The legend should be short and simple so that even a less educated driver can understand the message in less time.
- Road users must respect signs: Respect is only commanded when drivers are conditioned to expect all devices to convey meaningful and important messages. Overuse, misuse, and confusing device messages tend to be ignored by drivers.
- The control device should provide adequate time for proper response by road users: This again relates to the design aspect of the traffic control device. Signboards should be placed at such a distance that the driver can see them and have enough time to react to the situation. For example, a STOP sign, which is always placed on the stop line of an intersection, should be visible at least one safe stopping sight distance from the stop line.
Communication Tools
A traffic engineer uses a number of mechanisms to communicate with road users. These mechanisms recognize certain human limitations, especially vision. Messages are conveyed in the following manner.
Color
It is the first and most easily noticeable characteristic of the device. The use of different colours for different signs is important. The most frequently used colours are red, green, yellow, black, blue and brown. They are used to encode certain devices and to strengthen specific messages. Consistent use of colour helps drivers identify the presence of a signboard ahead.
Shape
It is the second element that the driver recognises next to the colour of the device. The commonly used shape categories are circle, triangle, rectangle and diamond shape. Two exceptional shapes used in traffic signs are the octagonal shape for the STOP sign and an inverted triangle for the sign GIVE WAY(YIELD). Diamond-shaped marks are generally not used in India.
Legend
This is the last element of the device that the driver understands. That’s an important point of view in the case of traffic signs. For easy understanding by the driver, the legend should be short, simple and specific so as not to distract the driver. The symbols are commonly used as legends so that even a person unable to read the language will be able to understand it. This is not necessary in the case of traffic signals and road markings.
Pattern
Commonly used in the application of road markings that complement road signs. Solid, double solid and dotted lines are generally used. Each pattern expresses a different type of importance. Frequent and consistent use of the pattern to convey information is recommended so that drivers get used to different types of markings and recognize them immediately.
Types Of Traffic Signs
There are several hundred traffic signs covering a wide range of traffic situations. They can be divided into three main categories.
Regulatory Signs
These signs require the driver to respect the signs for the safety of other road users.
Warning Signs
These signs serve for the safety of you, who is driving, and advise drivers to follow these signs.
Information Signs
These signs provide the driver with information about available facilities ahead and the route and distance to reach specific goals. In addition, special types of road signs are also available, namely work zone signs. These types of signs are used to warn road users when there is construction work on the road.
They are only placed for a short period of time and will be removed soon after the work is done and when the road will return to normal. The first three signs will be discussed in detail below. Regulatory signs are also called command signs because it is mandatory for drivers to obey these characters. If the driver does not obey them, the control authority has the right to take legal action against the driver. These signs are primarily intended for the safety of other road users. These characters generally have a black legend on a white background. They are circular in shape with a red border. Regulatory signs can be further divided into:
1. Right-of-Way Series
This includes two unique signs that grant the right-of-way to selected intersection approaches. They are the “STOP” sign and the “GIVE WAY” sign. For example, when a minor road and a main road meet at an intersection, preference should be given to the vehicles passing on the main road. That’s why there will be a signboard give way placed on a side road to inform the driver on the side road to give way to vehicles on the main road. In case two main roads meet, then the traffic engineer decides based on the traffic on which ramp the board must be placed. Stop sign is another example of regulatory signs that comes in the right of way series which requires the driver to stop the vehicle at the stop line.
2. Speed Range
Number of speed markers can be used to limit the speed of the vehicle on the road. They include typical speed limit signs, truck speed, minimum speed signs, etc. Speed limit signs are placed to limit the speed of a vehicle to a certain speed for a number of reasons. On high-speed roads with heavy freight traffic, separate truck speed limits apply vehicles must be limited to a lower speed than passenger cars for safety reasons. Minimal speed limits are enforced on high-speed roads such as expressways, highways, etc., where safety again is the overriding reason. Very slow vehicles can be a danger to themselves and other vehicles too.
3. Movement Lines
Contains a series of characters that emphasise specific manoeuvres of the vehicle. These include turn signs, directional signs, exclusion signs, one-way signs, etc. Turn signs include no-turns and lane-use control signs. Lane use signs use arrows to specify the movements that all vehicles in the lane must make. Turn signs are used to safely accommodate turns in un signalised intersections.
4. Parking Series
They include parking signs that indicate not only parking prohibitions or restrictions but also indicate the places where parking is allowed, the type of vehicle to be parked, parking time, etc.
5. Pedestrian Series
Includes both legend and symbol markers. These characters are intended for pedestrian safety and include signs indicating only pedestrian paths, crosswalks pages etc.
6. Miscellaneous
This category includes a wide variety of brands: a “KEEP OF MEDIAN” sign, signs indicating road closures, signs restricting vehicles carrying dangerous goods, cargo or substances, signs indicating vehicle weight restrictions, etc.
Parking
Marking the limits of parking spaces on city roads promotes the efficient use of the parking lot space and tends to prevent encroachment on places like bus stops, rehydrant zones etc. where parking is undesirable. Such parking restrictions should be marked in solid white lines with a width of 100 mm. The words TAXI, CARS, SCOOTERS etc. can also be written if the parking area is allotted for each particular type of vehicle. To indicate parking restrictions, the kerb or marking the road with a continuous yellow line 100 mm wide covering the top of the kerb or the road near it can be used.
Dangerous Location
Wherever there is a change in the width of the carriageway or at any dangerous place on the carriageway, the driver should be alerted to this situation using appropriate road signs. Traffic signs showing the width transition in the carriageway should be 100 mm wide. Converging lines should be 150 mm wide and their chamfer length is not be less than twenty times the offset distance.
A typical road marking showing the transition from wider to narrower sections and vice versa. In the picture, the driver is alerted to the location of the passing pier correct traffic signs.
Parking is one of the main issues caused by increasing road traffic. The availability of smaller spaces in urban areas has increased the demand for parking space, especially in areas such as the central business district. This has caused a huge economic impact.
Parking Study
Before considering any measures to improve conditions, parking availability data space, the extent of its use and the need for parking are essential. You also need to estimate parking fares too. All this information is to provide parking surveys. From the duration of parking is different for different vehicles, several statistics are used to access the parking requirements.
Parking Surveys
Parking surveys are conducted to collect the above parking statistics. The most frequently used parking surveys carried out are in-out surveys, exceeding the sampling period and license plate method surveys.
In-Out Survey
In this survey, the number of occupancy in the selected parking lot is taken in the beginning. Then the number of vehicles that enter the parking lot during a certain period of time the interval is calculated. The number of vehicles leaving the parking lot is also taken. Zero parking lot occupancy is also taken. Very less work is required here. However, we do not get any data on the time for which a particular vehicle was using this parking lot. Parking time and turnover is not attained. Therefore we cannot estimate the price of parking from this survey.
Fixed Period Sampling
This is very similar to the in-out survey. All vehicles are calculated at the beginning of the survey. Then after a fixed time interval that can vary between them.
After 15 minutes to 1 hour, the counting is done again. There is a chance that you will miss the number here due to short-term parked vehicles.
Number Plate Survey Method
The result is the most accurate and realistic data. In this case, the survey of each parking lot is monitored at a continuous interval of approx. 15 minutes and so on, the registration mark is noted. This will give you data on the time for which a particular vehicle is using a parking space. This will help in calculating the fare because the fare is estimated based on the time the vehicle has been parked. If the time interval is shorter, then there is less chance of missing short-term parkers. But this method is very laborious.
Conclusion
Traffic Planning and regulations play a very important role in Traffic engineering. It focuses mainly on the smooth and efficient flow of traffic. Without traffic engineers, our roadways would be underdeveloped and unsafe while yielding high-congestion accidents. It also enhances the functional aspects of road geometry that make everything flow, including road signs, traffic signals, intersection management and road surface markings.
