HRE-313-Module1-2.pdf

Chapter 1 Importance of Transportation Introduction: For as long as the human race has existed, transportation has played a significant role by facilitating trade, commerce, conquest, and social interaction, while consuming a considerable portion of time and resources. The primary need for transpor...

Chapter 1 Importance of Transportation Introduction: For as long as the human race has existed, transportation has played a significant role by facilitating trade, commerce, conquest, and social interaction, while consuming a considerable portion of time and resources. The primary need for transportation has been economic, involving personal travel in search of food or work, travel for the exchange of goods and commodities, exploration, personal fulfillment, and the improvement of a society or a nation. The movements of people and goods, which is the basis of transportation, always has been undertaken to accomplish those basic objectives or tasks that require transfer from one location to another. TRANSPORTATION AND ECONOMIC GROWTH - Good transportation, in and of itself, will not assure success in the marketplace, as the availability of transportation is a necessary but insufficient condition for economic growth. However, the absence of supportive transportation services will serve to limit or hinder the potential for a nation or region to achieve its economic potential. Thus, if a society expects to develop and grow, it must have a strong internal transportation system consisting of good roads, rail systems, as well as excellent linkages to the rest of the world by sea and air. Thus, transportation demand is a byproduct derived from the needs and desires of people to travel or to transfer their goods from one place to another. It is a necessary condition for human interaction and economic competitiveness SOCIAL COSTS AND BENEFITS OF TRANSPORTATION - The improvement of a region’s economic position by virtue of improved transportation does not come without costs. Building vast transportation systems requires enormous resources of energy, material, and land. In major cities, transportation can consume as much as half of all the land area. An aerial view of any major metropolis will reveal vast acreage used for railroad terminals, airports, parking lots, and freeways. Transportation has other negative effects as well. Travel is not without danger; every mode of transportation brings to mind some major disaster — be it the sinking of the Titanic, the infrequent but dramatic passenger air crashes, and highway accidents. In addition, transportation can create noise, spoil the natural beauty of an area, change the environment, pollute air and water, and consume energy resources. - Society has indicated a willingness to accept some risk and changes to the natural environment in order to gain the advantages that result from constructing new transportation systems. Society also values many social benefits brought about by good transportation. Providing medical and other services to rural areas and enabling people to socialize who live some distance apart are just a few examples of the benefits that transportation provides. - A major task for the modern transportation engineer is to balance society’s need for fast and efficient transportation with the costs involved Chapter 2 Different Modes of Transportation Introduction: The transportation system today is a highly developed, complex network of modes and facilities that furnishes shippers and travelers with a wide range of choices in terms of services provided. Each mode offers a unique set of service characteristics in terms of travel time, frequency, comfort, reliability, convenience, and safety. The term level of service is used to describe the relative values of these attributes. The traveler or shipper must compare the level of service offered with the cost in order to make tradeoffs and mode selection. Furthermore, a shipper or traveler can decide to use a public carrier or to use private (or personal) transportation. FREIGHT AND PASSENGER TRAFFIC - The principal modes of intercity freight transportation are highways, railroads, water, and pipelines. Air freight is an important carrier for high-value goods, but it is insignificant on a ton-mile basis - The four principal carriers for freight movement (rail, truck, pipeline, and water), account for varying proportions of total number of ton-miles of freight. The railroad’s share is highest on a ton-mile basis, but it has been reduced significantly due to competition from truck and pipeline. The railroads have lost traffic due to the advances in truck technology and pipeline distribution. - The distribution of passenger transportation is much different from that for freight: one mode—the automobile—accounts for the highest number of all domestic intercity passenger-miles traveled in the United States. The remaining modes — air, bus, and rail — shared a market representing about one-quarter of the total, with air being the dominant mode and intercity bus, private air carriers, and rail representing 1 percent or less of the total. - Of the four transportation carriers for intercity passenger movement, two—air and auto — are dominant. In cities, buses are the major public transit mode, with the exception of larger urban areas that have rapid rail systems PUBLIC TRANSPORTATION - The principal modes of intercity freight transportation are highways, railroads, water, and pipelines. Air freight is an important carrier for high-value goods, but it is insignificant on a ton-mile basis 1. Transit Modes The modes included within the realm of public transportation are: a. Mass transit, characterized by fixed routes, published schedules, designated networks, and specified stops. Mass-transit vehicles include buses, light rail (trolleys) or rapid transit that either share space in mixed traffic or operate on grade-separated rights of way. b. Paratransit is characterized by flexible and personalized service intended to replace conventional fixed-route, fixed-schedule mass-transit lines. Paratransit is available to the public on demand, by subscription, or on a shared-ride basis. Examples include taxi, car rental, dial-a-ride, and specialized services for elderly, medical, and other designated users. c. Ridesharing (as the name implies) is characterized by two or more persons traveling together by prearrangement, such as carpool, vanpool, or shared-ride taxi. COMPARATIVE ADVANTAGES OF TRANSPORTATION MODES - Each mode has inherent advantages of cost, travel time, convenience, and flexibility that make it “right for the job” under a certain set of circumstances. The automobile is considered to be a reliable, comfortable, flexible, and ubiquitous form of personal transportation for many people. However, when distances are great and time is at a premium, air transportation will be selected—supplemented by the auto for local travel. If cost is important and time is not at a premium or if an auto is not available, then intercity bus or rail may be used. - Selecting a mode to haul freight follows a similar approach. Trucks have the advantages of flexibility and the ability to provide door-to-door service. They can carry a variety of parcel sizes and usually can pick up and deliver to meet the customer’s schedule. Waterways can ship heavy commodities at low cost, but only at slow speeds and between points on a river or canal. Railroads can haul a wide variety of commodities between any two points, but usually require truck transportation to deliver the goods to a freight terminal or to their final destination. In each instance, a shipper must decide whether the cost and time advantages are such that the goods should be shipped by truck alone or by a combination of truck, waterway, and rail. Table 1. Transportation Modes Figure 1. Selecting a Transportation Mode Solution: Since travel time is valued at $25/hr, the following costs would be incurred: Air: 250 + 25 (5) = $375 Auto: 200 + 25 (8) = $400 Rail: 150 + 25 (12) = $450 In this instance, the air alternative reflects the lowest cost and is the selected mode. However, the traveler may have other reasons to select another alternative. Consideration for selecting alternative transportation mode: A. Safety - While each of these modes is safe, the traveler may feel “safer” in one mode than another. For example, rail may be preferred because of concerns regarding air safety issues. B. Reliability - If it is very important to attend the meeting, the traveler may select the mode that will provide the highest probability of an on- time arrival. If the drive involves travel through work zones and heavily congested areas, rail or air would be preferred. If potential air delays are likely due to congestion, flight cancellations, or inclement weather, another mode may be preferred. C. Convenience - The number of departures and arrivals provided by each mode could be a factor. For example, if the railroad provides only two trains/day and the airline has six flights/day, the traveler may prefer air travel. Chapter 3 Characteristics of Road Transit Introduction: Roads are used by various types of road vehicles, like passenger cars, buses, trucks two and three wheeled automobiles, pedal cycles and animal drawn vehicles. But railway tracks are used only by rail locomotives and wagons, water ways are used by only ships and boats - Road transport requires a relatively small investment for the government. Motor vehicles are much cheaper than carriers like rail locomotives and wagons, water and air carriers. Construction and maintenance of roads is also cheaper than that of railway track, docks, harbors and airports. - Road transport completely offer freedom to road users to transfer the vehicles from one lane to another and from one road to another according to the need and convenience. This flexibility of changes in location, direction, speed and timings of travel is not available to other modes of transport. - In particular for short distance travel, road transport saves time. Trains stop at junctions and main stations for comparatively longer time. - Speed of movement is directly related with severity of accident. The road safety decreases with increase dispersion in speed. Road transport is subjected to high degree of accidents due to flexibility of movements offered to the user. Derailment of railway locomotives and air planes and air crashes are not uncommon. They are in fact more disastrous. - Road transport is the only means of transport that offer itself to the whole community. - Road transport is a basic need in case of fire and police protection. - It gives door step connectivity even in case of rural area or villages - It is important access to reach railways, waterways and airways. - The Major defect of road is Traffic. Chapter 4 Scope of Highway and Traffic Engineering Introduction: Highway engineering and traffic analysis involve an extremely complex interaction of economic, behavioral, social, political, environmental, and technological factors. This complexity makes highway engineering and traffic analysis far more challenging than typical engineering disciplines that tend to have an overriding focus on only the technical aspects of the problem. To be sure, the technical challenges encountered in highway engineering and traffic analysis easily rival the most complex technical problems encountered in any other engineering discipline. However, it is the economic, behavioral, social, political, and environmental elements that introduce a level of complexity unequalled by any other engineering discipline. In nutshell, it may be said that the highway engineering deals with various phase like development, planning, alignment, highway geometric design and location, highway traffic operation and its control, materials, pavement design, construction and maintenance, economic considerations, finance and administration. Many other special aspects which are not included in the general layout are related to problems of development and construction of hill-roadside development including landscaping road architecture and arboriculture. Figure 2. Scope of Highway Engineering Chapter 1 Importance of Highway Development and Planning Introduction: The planning process striving to balance the provision of direct links to communities simultaneously ensuring the smooth and safe flow of traffic in the road system is broadly termed Access Management. It involves aspects of planning of road design in terms of the number and form of links to major roads, as well as the management of the flow of traffic between these roads. Various techniques are used to manage entrances and exits and related turning movements onto and off the major roadways, as well as maintain design criteria and standards necessary to preserve the operational capacity, speed and safety of the roadways. Every access point can contribute to the deterioration of traffic level of service and these impacts increase geometrically over time as both the traffic volumes and number of access points increase. Access management must therefore accommodate not only the current condition but also the future growth. Systematic application of planning, design, and operation of access management features includes approaches (driveways and street connections to a roadway), medians, median openings, signals, auxiliary lanes, and interchanges. 1.1 IMPORTANCE - The ultimate goal of road planning is to ensure safe and smooth flowing traffic conditions through the entire system of roads. While it is important that the roadways must have sufficient capacity to accommodate the traffic demand, it is critical to recognize that road design and management should be undertaken to ensure that the available capacity is not unduly affected by creation of unnecessary bottlenecks and conflicts. - A long-term land-use transport plan should be developed to determine not only the functional class of a particular roadway but also to establish the estimated life of that roadway within the class. An area may avoid expensive modifications of existing roadways to sustain its functional position within a particular class if it is clear from the long-term plan that the roadway may be displaced to an access function when a proposed new roadway is built later on. In the process, planners also avoid dealing with the fallout negative impacts of road modifications, perceived or real, on the adjacent communities. - Poor access management design leads to increased delays and also causes unnecessary air pollution and fuel consumption (time spent idling at red lights or in stop-and-go traffic). A study by Ohio – Kentucky – Indiana Regional Council of Governments concluded that 40% of all fuel consumption in highway transportation was attributable to vehicles stopped and idling at traffic signals (OKI, 1999). Frequent and poorly spaced traffic signals can reduce roadway capacity to over 50%. Furthermore, access management is also a safety issue as 50 to 60% of crashes are access related. 1.2 PRINCIPLES OF ACCESS MANAGEMENT - A systematic access management policy addresses the questions of why, when, where, and how access should be provided or denied, and what legal or institutional changes are needed to enforce these decisions (AASHTO, 2001: 89). Depending on the function of the road, access may be fully controlled where priority is given to through-traffic or partially controlled to preserve a desirable balance between access and mobility. Building on traffic engineering concepts and ideas, access management seeks to reduce and separate conflict points in a roadway system and minimize interference to traffic flow. A carefully conceived and well implemented access management plan can help to preserve the capacity, speed, and safety of traffic on a road system extending its life span and reducing the need to build new roadways. - The access management principles can be broadly summarized into the following: 1. Develop a functional system of classification of roadways, and define the roadways in the system in terms of these classes: The classification scheme will show where each roadway in an area is placed in its functional range between access and mobility, and provide framework for assessment of need for different types of access management & control measures. 2. Provide a balanced road circulation system: The functional integrity of a highway system at the city and regional scales rests on the development of a graduated system of roadways that facilitates a balanced and well distributed circulation of traffic. This establishes a sound framework for the effective functioning of roadways in accordance with their defined categories in the classification system. 3. Establish access control to roadways with higher functional classifications: Freeways and expressways are reserved for the mobility function. Direct property access should be restricted and the entrances to these higher-class roadways need to be carefully planned in terms of location, spacing, and other design features. 4. Establish standards on driveways that feed into collector and arterial roads: Junctions between driveways and the main roads represent conflict points that can affect smooth traffic flow and increase the potential for accidents. Regulations and guidelines on driveway spacing, frequency, design, and location will help to reduce the severity of these conflicts. 5. Plan the location and design of major intersections: The flow of traffic through intersections needs to be carefully coordinated to allow for smooth progression. Driveways need to be located at a reasonable distance away from intersections to reduce traffic interferences. 6. Promotes development of dedicated turning lanes & other special turning treatments: If the lanes on a roadway carry both through-flow and turning traffic, disruptions and conflicts arise, and these can result in bottle-necks that pose congestion and potential accident problems. By separating turning traffic from through-flow traffic, these conflicts can be reduced, resulting in the safe and effective functioning of the roadway. 7. Consider the application of median treatments including raised medians and two- way left turn lanes (TWLTL): These are among the most controversial measures of access management but are highly effective in reducing conflicts along roadway stretches brought about by turning and crossing traffic. 8. Assess economic impacts and involve public participation in access management policy initiatives: This helps to assess level of acceptance, create awareness of the long-term benefits of access management, and evaluate the effectiveness of measures. 1.2.1 CLASSIFICATION OF RAODWAYS - The first question that is asked when a road is built relates to the function that it is going to serve. At the lowest level, there is a local road that provides access to individual housing units in small residential neighborhood. The local roads feed into collector roads that link up multiple neighborhoods. The collector roads feed into the minor arterial roads, which in turn link to the major arterials that provide connections between large scale community networks. At the highest level, there are the freeways and expressways that carry regional and intercity traffic. The size of roads in each road class depends on the density of the activities, be it housing, industrial, office, or other activities, as this will have a bearing on the volume of traffic generated. This will be discussed more in Content #2 of this Module 2. 1.2.2 BALANCED ROAD CIRCULATION SYSTEM - Once a long-term plan is mapped out with a clear functional hierarchy of existing & proposed roadways, planners can develop standards & controls on number of access points & adopt various techniques to improve the form of access at each point. - In his landmark study, Marks (1974) proposed a graduated system of roadways in which each functional class of roads was served by the next class in the hierarchy. This concept of graduated access represents one useful foundation for guiding the practice of access management. Such a system of roadways allows a driver to make a smooth transition from a lower speed roadway to a higher speed one in a way that promotes safety and efficient traffic flow. - If, for instance, there is a collector road with a design speed of 40 km/h feeding directly into a freeway with a speed of 90 km/h, it would be difficult and dangerous for the driver to increase the vehicle speed as he enters the freeway or reduce the speed as he leaves the freeway. Unless special provisions are made, this large speed differential will create bottleneck situations in the ramp area and potentially impede smooth traffic flow. - A graduated system of roadways will provide good circulation of traffic only if the supply of roadways at each level is adequate and if the roadways of different regions are well-connected. The inadequate provision of secondary roads, for example, will result in the arterial roads accommodating both local and through traffic, when they are functionally designed primarily for the latter. If a large percentage of drivers intending to travel from one traffic zone to an adjacent zone, go into a freeway & then take the next exit to enter the adjacent zone, the function of the freeway to provide a through-link for travel between spatially distant zones becomes compromised. 1.2.3 ESTABLISH STANDARDS ON ACCESS CONTROLS TO FREEWAYS, EXPRESSWAYS, AND MAJOR ARTERIALS - The availability of good internal circulation between neighboring districts may still not deter drivers from using the high-speed roadways for short trips. Access controls to the major roadways is therefore necessary to encourage drivers to use the system of minor arterials and other lower order roadways for short distance commutes, and take the freeway only for long distance rides. - The key considerations for access management into high-speed freeways relate to the design or form of access points and the spacing between them. Freeways serve continuous traffic flow &, as such, should not encounter any signalized intersections. Opposing traffic movements must be separated by physical medians or concrete rail barriers, & cross traffic should be separated by grade separation structures. Directional ramps, in the form of interchanges, limit the access to freeways. 1.2.4 STANDARDS ON NUMBER, LOCATION AND DESIGN OF DRIVEWAYS, AND SIGNALIZED INTERSECTIONS - While access to freeways and principal arterials is generally restricted, access to smaller arterials and collector streets also needs to be regulated and properly designed. In the local development guide plans or ordinances, special conditions could be stipulated to limit the number of driveways to one per parcel, and to encourage the use of side roads or shared driveways. Geometric design has a direct impact on vehicle operating speed, traffic engineering, and the eventual safety of low speed urban streets. - Geometric design must balance access, pedestrian or bicycle use, and right-of-way issues with speed and safety. If vehicles operate above the intended speed, speed differentials can result between vehicles and increase the risk and severity of potential accidents. The potential for speed differential between vehicles also increases with the number of conflict points created when vehicles enter streets from driveways and intersections. This will be further discussed in the coming modules. 1.2.5 PROMOTING THROUGH-FLOW AT SIGNALIZED INTERSECTIONS - For major at-grade signalized intersections such as between an arterial and a collector street, minimum distance standards need to be maintained to preserve traffic flow, improve safety and sustain the functional hierarchy of the road system. A corollary effect of increasing the distance between signals is the improvement of air quality in heavily traveled high-density corridors. Traffic signals serve to assign right- of-way to conflicting movements of traffic at intersections. While they reduce the number of right-angle collisions at an intersection, they can cause an increase in rear- end collisions. A balance therefore needs to be achieved with due safety considerations to maintain a smooth traffic flow. It is important that signalized access points on major roadways must be considered in a total city or region wide traffic coordination scheme. - The appropriate spacing between signalized intersections on a particular arterial stretch depends on the speed of the road and density of traffic, but it is noted that “anything greater than two per mile has a significant impact on congestion and safety” (FHWA, 2003). However, depending on the density of land use, this spacing standard may be reduced but a minimum spacing of at least 1/4 mile should be maintained, as any further reduction will lead to unacceptable disruptions in traffic flow in the form of delays and queues at intersections. - Apart from the spacing of signalized intersections, the quality of flow along a street is also affected by the speed of traffic on the street, and length of the traffic signal cycle. Synchronization of adjacent traffic signals (green waves) helps to reduce stops and delays. This can be best achieved using a system of traffic-actuated signals, which adjusts the green time according to the volume of traffic, optimizing flow at the intersections. It is more difficult to achieve in two-way streets because of the need to coordinate opposing traffic movements. Several cities have implemented some variant of this system on their arterial road network. Access and mobility management efforts can be optimized when they are complemented with such road management measures that use intelligent transportation system (ITS) tools. 1.2.6 TREATMENTS ON TURNING LANES - Access controls to major arterials in the form of driveway consolidation and other management measures facilitate the speedier movement of through-flow traffic. However, when if a lane on the roadway serves both turning and through-flow traffic, disruptions referred to as “side friction” may be encountered because of the sudden deceleration of speeds of the traffic intending to turn at intersections. This creates conflicts or bottlenecks under heavy traffic flow bringing about long queues of traffic waiting to turn left & right, & constrictions in the passageway of through-flow traffic. - As left-turning vehicles are provided a separate space to slow down and wait for gaps in traffic, the interference to through-traffic in the remaining lanes is minimized (AASHTO, 2001: 479). The construction of dedicated lanes for traffic turning at intersections can therefore help to separate turning traffic from through- flow traffic, reduce conflicts and promote safety and improved traffic flow. Major arterials with high traffic volumes and relatively high posted speeds can benefit most from such lanes, including right-turn acceleration lanes, auxiliary left-turn lanes, and auxiliary right-turn lanes. - A traffic impact study will have to be carried out to determine the need for turning lanes based on the existing traffic volumes, speed and the projected impact of the proposed use, and make recommendations on the design of the turning lane. In general, the length of the turning lane should be a minimum two car-lengths and based on the number of vehicles likely to arrive in a 2-minute period at peak hour (unsignalized) or the signal length and timing. 1.2.7 MEDIAN TREATMENTS - Traffic flow on an arterial is often impeded by the intermittent stoppage of vehicles intending to turn left into small driveways, but this does not generally pose severe problems when the traffic volume is low. When the flow becomes heavy, for example, during peak hours serious bottleneck situations may arise, and such turning traffic may contribute to massive congestion and safety problems. - Median treatments for roadways represent one of the most effective means to control access to small driveways. They serve a dual role of separating opposing traffic movements and managing left turns and crossing movements between driveways and arterials. By controlling left turning movements, conflicts between through and turning traffic can be reduced, resulting in improved safety. Medians are most effective in roadways with high volumes and four or more lanes of traffic. 1.2.8 ECONOMIC IMPACTS OF ACCESS MANAGEMENT AND PUBLIC PARTICIPATION - From the point of view of a business enterprise located along an arterial, direct access of the property to the roadway is often desired as it is perceived to contribute to higher levels of customer flow, increased sales and higher property value. Businesses become naturally concerned about the negative impact of the reduced accessibility resulting from the need to make circuitous trips following various access management measures such as driveway consolidation, median treatments, and the conversion of streets from two-way to one-way driveways. Such perceived negative impacts can sometimes lead to a stalemate in proposed access management projects. - The resistance to such measures is more pronounced when existing roadways where the businesses are already located become earmarked for new access management treatments. It is likely that when the roadway was first built, the high growth rates in the traffic volumes was perhaps not expected, and the land use and access standards were not that tightly regulated. However, the surge in traffic and, consequently, the serious congestion and safety problems may leave city and state authorities with little choice and they have to take these measures to improve the efficiency of movement of traffic along major roads. In newly developed land, the problem of acceptance is less serious but still prevails. It is easier to review and modify the local ordinances and building plans to ensure that access management standards and guidelines are followed in the development of new residential and business districts. However, “considerable political pressure is often exerted to reduce the amount of access control because of fears that developers may be turned off and decide to build elsewhere or that voters may object to perceived inconvenience and risks.” Take note of these following surveys: 1) In 1995, a survey was conducted both on drivers and business owners in Florida on the impact of raised medians on specific corridors and the results indicated that while the general perception was an additional inconvenience would be caused by the median, it was more than compensated by smoother traffic flow and improved safety. Results of the survey show that:  78% of the drivers surveyed felt safety had improved while  84% felt traffic moved better.  30% of the business owners noted that they had experienced some negative impacts such as delivery difficulties and reduction in business volume e (Ivey et al., 1995). 2) Another study looking at impacts of access management projects in southeast Florida found that:  26% of the business owners reported a loss in profits after the measures were implemented  5% reported a gain;  the remaining large majority of businesses saw little or no negative impact of their profitability, number of customers, or property values (Vargas and Gautam, 1989). - It is apparent that a reduction in level of direct access is a real cause for concern for owners of businesses & other developments. However, it is often not appreciated that the conflicts resulting from poor or excessive access points contribute to congestion and delays in the community’s roadway system, making the very region where the businesses are located inaccessible and unattractive. In the long term, the region will lose its economic vitality and businesses will move out to higher quality locations. Clearly, there is a need for transportation authorities to engage with the community in its access management policy, to explain the rationale, demonstrate the community- scale and long-term benefits by drawing from similar projects elsewhere, and ensure that the project is planned and designed in a way that incorporates the more critical concerns of the stakeholders. Chapter 2 Environmental Impact of Highway Development Introduction: Highway development enhances mobility and is critical to the economic growth of a community and a country as a whole. Unfortunately, inappropriately planned, designed, and constructed highways can aggravate the conditions of the poor, and harm the natural and socio-economic environment. The common adverse impacts of highway development include:  damage of natural landscape,  habitat and bio-diversity,  destruction of cultural and social structure of affected communities,  creation of air and water pollution, and  generation of noise and vibration Environmental impacts of highway development can be grouped under the following categories: a) direct and indirect d) short- and long-term b) cumulative e) temporary and permanent c) local and widespread f) random and predictable In highway development projects, it is useful to distinguish between highly probable impacts from random or unpredictable impacts with a low probability of occurring but may have serious consequences. For example, the construction of a highway through a large, densely populated area will result in population displacement and business loss. On the other hand, incidents such as accidental pollution, fire, or spillage of toxic products are, by nature, unpredictable. To minimize adverse environmental and socio-economic impacts, highway infrastructure must be built to a high quality and maintained to a high standard. This can be achieved by integrating environmental considerations into highway development planning, design, and construction. The process consists of three key elements:  Identification of the full range of possible impacts on the natural and socio- economic environment;  Evaluation and quantification of these impacts and  Formulation of measures to avoid, mitigate & compensate for anticipated impacts The possible mitigation measures include:  changing project sites, routes, processes, raw materials, construction methods, operating methods, and disposal locations of wastes and spoils  introducing pollution controls, waste treatments, monitoring, phased implementation, landscaping, personnel training, special social services, or public education  offering (as compensation) restoration of damaged resources, money to affected persons, concessions on other issues, or off-site programs to enhance some other aspects of the environment or quality of life for the community. Cost of all mitigation measures must be quantified. Various mitigation measures are then compared and trade- offs between alternative measures are weighed. Several analytical techniques are available for this purpose: a) Cost-benefit analysis in which all quantifiable factors are converted to monetary values, and actions are assessed for their impacts on the highway project costs and benefits. However, the unquantifiable factors can be equally important, and need to be taken into account in the decision-making process; b) Explaining what course of actions would follow from various broad value judgments (e.g., those socio-economic impacts are more important than resources); c) A simple matrix of environmental and socio-economic parameters vs. mitigation measures, containing brief descriptions of the effects of each measure; d) Pair wise comparisons, whereby the effects of an action are briefly compared with the effects of each of the alternative actions, one pair at a time. The process which systematically deals with these elements is called Environmental Impact Assessment (EIA). The end results are presented in an EIA report including an Environmental Management Plan (EMP). It must be emphasized that an EIA process is not solely aimed at identifying, quantifying, and mitigating the negative impacts of a highway development project. It should also be used to optimize positive impacts of the project (World Highways, 2001). Chapter 3 Classification of Roads Introduction: Roadways are a major component of the traffic system and the specifics of their design have a significant impact on traffic operations. Two primary categories of service provide by roadways and roadway systems are: 1. Accessibility – refers to the direct connection to abutting lands and land uses provide by roadways. This accessibility comes in the form of curb parking, driveway access to off-street parking, bus stops, taxi stands, loading zones, driveway access to loading areas, and similar features. The access function allows a driver or passenger (or goods) to depart the transport vehicle to enter the particular land use in question. 2. Mobility – refers to the through movement of people, goods, and vehicles from Point A to Point B in the system. On the two extremes, the design of local streets emphasizes access with little consideration for mobility, while the design of freeways emphasizes mobility with limited access. The design of collectors and arterials falls in between, with collectors emphasizes more for access and arterials favors mobility. 3.1 TRIP FUNCTIONS The American Association of State Highway and Transportation Officials (AASHTO) defines up to six distinct travel movements that may be present in a typical trip:\ 1. Main movement – is the through portion of trip, making the primary connection between the area of origin and the area of destination. 2. Transition – occurs when a vehicle transfers from the through portion of the trip to the remaining functions that lead to access and termination. A vehicle might, for example, use a ramp to transition from a freeway to a surface arterial. 3. Distribution – involves providing drivers and vehicles with ability to leave a major through facility and get to the general area of their destinations. 4. Collection – brings the driver and vehicle closer to the final destination. 5. Access and 6. Termination – provides the driver with a place to leave his or her vehicle and enter the land parcel sought. The hierarchy of trip functions should be matched by the design of the roadways provided to accomplish them. A typical trip has two terminals, one at the origin and one at the destination. At the origin end, the access function provides an opportunity for the trip-maker to enter a vehicle and for the vehicle to enter the roadway system. The driver may go through a series of facilities, usually progressively favoring higher speeds and through movements, until a facility – or set of facilities – is found that will provide the primary through connection. At the destination end of the trip, the reverse occurs, with the driver progressively moving toward facilities favoring access until the specific land parcel desired is reached. 3.2 HIGHWAY CLASSIFICATION All highway systems involve hierarchal classification by the mix of access and mobility functions provided. Four major classes of highways may be identified: 1. Limited-access facilities – provides for 100% though movement, or mobility. No direct access to abutting land uses is permitted. 2. Arterials – surface facilities designed primarily for through movement but permit some access to abutting lands. 3. Collectors – is an intermediary category between arterials and local streets. Some measure of mobility and access is provided. The term collector comes from a common use of such facilities to collect vehicles from a number of local streets and deliver them to the nearest arterial or limited access facility. 4. Local streets – designed to provide access to abutting land uses with through movement only a minor function, if provided at all. The typical trip starts on a local street. The driver seeks the closest collector available, using it to access the nearest arterial. If the trip is long enough, a freeway or limited-access facility is sought. At the destination end of the trip, the process is repeated in reverse order. Depending on the length of the trip and specific characteristics of the area, not all of the component types of facilities need to be included in every trip. Freeways and expressways are designed for maximum mobility with high speeds and capacities. If there are limited or no controls on the access points to a major freeway or expressway, the capacity, efficiency of travel, and safety levels of the roadway may be compromised. This is why access to the large regional highways needs to be strictly controlled to interchanges spaced many kilometers apart. On the other hand, a local street, which has individual links to adjacent properties cannot be expected to serve a long-distance mobility function. With a significant reduced volume of traffic flowing at low speeds, the function of these local roadways is primarily one of access. The remaining roadways, the collectors and arterials serve a mix of access and mobility functions, and the land use and traffic characteristics would largely determine where they are placed between the access – mobility continuum. It must be emphasized that the descriptions in the table are presented as typical. Each highway agency has its own highway classification system, and many have features that are unique to the agency. 3.3 PRESERVING THE FUNCTION OF A FACILITY Highway classification systems enable traffic engineers to stratify the highway system by functional purpose. It is important that the intended function of a facility be reinforced through design and traffic controls. The arterials have their function strengthened by limiting the number of points at which vehicles can enter or leave the arterial. Other aspects of an arterial that could also help reinforce their function include the following:  Parking prohibitions  Coordinated signals providing for continuous progressive movement at appropriate speeds  Median dividers to limit midblock left turns  Speed limits appropriate to the facility and its environment Figure 2 illustrates how the design and layout of streets within a suburban residential subdivision can reinforce the intended purpose of each facility. The character of local streets is assured by incorporating sharp curvature into their design and though the use of cul-de-sacs. No local street has direct access to an arterial; collectors within the subdivision provide the only access to arterials. The nature of collectors can be strengthened by not having any residence on the front of collector. In many older cities, it is difficult to separate the function served by various facilities due to basic design and control problems. The historic development of many older urban areas has led to open-grid systems. In such systems, local streets, collectors and surface arterials all form part of the grid. Every street is permitted to intersect every other street, and all facilities provide some land access. The only thing that distinguishes an arterial in such system is its width and provision of progressive signal timing to encourage through movement. Chapter 4 Road Patterns Introduction: Systems often experience difficulties when development intensifies, and all classes of facility including arterials are subjected to heavy pedestrian movements, loading and unloading of commercial vehicles, parking and similar functions. Because local streets run parallel to collectors and arterials, drivers experiencing congestion on arterials often reroute themselves to nearby local streets, subjecting them to unwanted and often dangerous heavy through flows. 4.1 RECTANGULAR OR BLOCK PATTERN In this pattern, the whole area is divided into rectangular blocks of plots, with streets intersecting at right angles. The main road which passes through the center of the area should be sufficiently wide and other branch roads may be comparatively narrow. The main road is provided a direct approach to outside the city. Advantages: 1) The rectangular plots may be further divided into small rectangular blocks for construction of buildings placed back to back, having roads on their front. 2) In this pattern has been adopted for the city roads. 3) The construction and maintenance of roads of this pattern is comparatively easier. Limitations: 1) This pattern is not very much convenient because at the intersections, the vehicles face each other since the roads are perpendicular to each other. This increases the rate of accidents due to poor visibility at a perpendicular junction. 4.2 RADIAL OR STAR AND BLOCK PATTERN In this pattern, the entire area is divided into a network of roads radiating from the business outwardly. In between radiating main roads, the built-up area may be planned with rectangular block. Advantage: 1) Less risky as compared to the rectangular pattern. 2) Reduces level of congestion at the primary bottleneck location. 3) Prevents traffic from accessing local flow routes in the direction of the event venue that operate in favor of egress traffic flow. 4) If one is blocked then other side can be used as an alternative. Limitations: 1) Proves particularly effective if two-lane ramp traffic does not have to merge at downstream end of ramp. 2) Lack if safety appurtenances like rail transitions, crash attenuators & post support base 4.3 RADIAL OR STAR AND CIRCULAR PATTERN In this system, the main radial roads radiating from central business area are connected together with concentric roads. In these areas, boundary by adjacent radial roads and corresponding circular roads, the built-up area is planned with a curved block system. Advantages: 1) At traditional intersections with stop signs or traffic signals, some of the most common types of crashes are right-angle, left-turn, and head-on collisions. These types of collisions can be severe because vehicles may be traveling through the intersection at high speeds. With circular pattern, these types of potentially serious crashes essentially are eliminated because vehicles travel in the same direction. 2) Roundabouts present in this pattern improves the efficiency of traffic flow. This also reduces fuel consumption and emission of the vehicle. 3) Installing circular pattern in place of traffic signals can also reduce the likelihood of rear-end crashes. Limitations: 1) Approach roads should be sufficiently curved, far enough in advance of circular pattern, to reduce vehicle speeds of entering drivers. 2) It affects the driving ability. Mainly old drivers face this problem due to decline in vision, hearing and cognitive functions. Intersections can be especially challenging for older drivers. 3) Splitter islands should be extended far enough to provide pedestrian refuge (crosswalk) and to delineate the roundabout. 4) Traffic signs, pavement markings, and lighting should be adequate so that drivers are aware that they are approaching a roundabout and that they should reduce their travel speed. 4.4 RADIAL OR STAR AND GRID PATTERN Change in direction, and because street patterns are the most enduring physical element of any layout, it could potentially contribute to systematic site planning &, consequently, deserves a closer look. Though the network is entirely interconnected, north-south movement becomes circuitous, indirect, & inconvenient, making driving an unlikely choice & vividly illustrating that interconnections by itself is insufficient to facilitate movement. Advantages: 1) Keep vehicular traffic safe with a high proportion of 3-way intersections. 2) Reduce cut-through traffic by similar or other means. 3) Improve traffic flow in both directions using Savannah’s cellular structure. 4) Improve land use efficiency and unit density. Limitations: 1) Islands separating the approach and exit lanes, known as splitter islands, should extend far enough. 2) Traffic signs, pavement markings, and lighting should be adequate so that drivers are aware that they should reduce their travel speed. 4.5 HEXAGONAL PATTERN In this, the entire area is divided into hexagonal patterns. Three roads meet the build-up area boundary by the sides of the hexagons at every corner of the hexagon which can be further divided into suitable sizes. Advantages: 1) Three roads meet the built-up area boundary by the sides of the hexagons. Limitations: 1) Traffic signs, pavement markings, and lighting should be adequate so that drivers are aware that they should reduce their travel speed. 4.6. MINIMUM TRAVEL ROAD PATTERN In this road pattern, the town is contented by sector centers, suburban facilities and neighborhood centers by the highway which required minimum time reach the city center. Advantage: 1) This type of road pattern ends potentially serious crash. Limitations: 1) Traffic signals, pavement marking and lighting should be sufficient, so that drivers know that they should reduce their travel speed. 2) Intersections can be particularly challenging for older drivers. Chapter 5 Planning Surveys Introduction: Planning with respect to road construction takes into account present and future uses of the transportation system to assure maximum service with a minimum of financial and environmental cost. The main objective of this initial phase of road development is to establish specific goals and prescriptions for road network development along with the more general location needs. These goals must result from a coordinated effort between the road engineer and the land manager, forester, geologist, soil scientist, hydrologist, biologist and others who would have knowledge or recommendations regarding alternatives or solutions to specific problems. The pattern of the road network will govern the total area disturbed by road construction. The route planning phase is the time to evaluate environmental and economic tradeoffs and should set the stage for the remainder of the road development process. Although inclusion of design criteria for sediment control may increase initial capital outlay, it does not necessarily increase total annual cost over the life of the road which might come from reductions in annual maintenance, reconstruction, and repair costs. If an objective analysis by qualified individuals indicates serious erosional problems, then reduction of erosional impacts should be a primary concern. In some areas, this may dictate the location of control points or may in fact eliminate certain areas from consideration for road construction as a result of unfavorable social or environmental costs associated with developing the area for economic purposes. Planning surveys consists of following studies: 1) Economic Studies It is important to find the service given by each road system to the population and products. Before estimation the requirement such that economic justification can be made details pertaining to the existing facilities should be available. The details to be collected include the following:  Population & its distribution in each village town or other locality with the area classified in groups  Trend of population growth  Agricultural and industrial products and their listing in classified groups, area wise.  Industrial and Agricultural development and future trends  Existing facility with regards to communication recreation and education  Per capita income 2) Financial Studies The financial studies are essential to study the various financial aspects like source of income and the manner in which funds for the project may be mobilized.  Source of income and estimated revenue from taxation on road transport  Living Standard  Resources at local level, toll taxes, vehicle registration and fines.  Future trends in financial aspects. 3) Traffic or Road use Studies All the details of the existing traffic their volume and pattern of flow should be known before any improvement could be planned. Traffic surveys should be carried out in the whole area and on selected routes and locations in order to collect the following particulars.  Traffic volume in vehicles per day, annual average daily traffic, peak and design hourly traffic volume  Origin and Destination Studies  Traffic flow patterns  Mass transport facilities  Accidents, their cost analysis and causes  Future trend and growth in traffic volume and goods traffic, trend in traffic pattern.  Growth of passenger trips and the trend in the choice of modes. 4) Engineering studies All details of the topography, soil and other problems such as drainage, construction and maintenance problems should be investigated before a scientific plan or program is suggested. The studies include.  Topographic survey  Soil Survey  Location and classification of existing roads  Estimation of possible developments in all aspects due to the proposed highway development  Road life Studies  Special Problems in drainage, construction and maintenance of roads. Interpretation of planning survey 1) To arrive at the road network, out of the several alternate possible systems, which has maximum utility 2) To fix up priority of construction projects, so as to phase the road development plan of an area in different periods of time such as five-year plan and annual plans 3) To assess the actual road use by studying the traffic flow patterns. This data may therefore show areas of congestion, which need immediate relief. 4) Based on the traffic type and intensity and performance of existing type of pavements and cross drainage structures, a new structure may be designed using the data and past experience Chapter 6 Highway Alignment and Surveys Introduction: The alignment of a highway is a three-dimensional problem measured in x, y, and z coordinates. This is illustrated, from a driver’s perspective, in Fig. 10. However, in highway design practice, three-dimensional design computations are cumbersome, and, what is perhaps more important, the actual implementation and construction of a design based on three-dimensional coordinates has historically been prohibitively difficult. As a consequence, the three-dimensional highway alignment problem is reduced to two two- dimensional alignment problems, as illustrated in Fig. 11. One of the alignment problems in this figure corresponds roughly to x and z coordinates and is referred to as horizontal alignment. The other corresponds to highway length (measured along some constant elevation) and y coordinates (elevation) and is referred to as vertical alignment. Referring to Fig. 11, note that the horizontal alignment of a highway is referred to as the plan view, which is roughly equivalent to the perspective of an aerial photo of the highway. The vertical alignment is represented in a profile view, which gives the elevation of all points measured along the length of the highway (again, with length measured along a constant elevation reference). Aside from considering the alignment problem as two two-dimensional problems, one further simplification is made: instead of using x and z coordinates, highway positioning and length are defined as the distance along the highway (usually measured along the centerline of the highway, on a horizontal, constant elevation plane) from a specified point. This distance is measured in terms of stations, with each station consisting of 100 ft of highway alignment distance. This will be further discussed in the next modules. The growth of direct access links to arterials and highways and the poor management of roads in relation to turning and through traffic contribute to the deterioration of the functional integrity of the roadway system. The development of new land uses and access points coupled with the traffic volumes reduces the speed and capacity of the adjacent roadways and increases congestion and accidents. Access management can ameliorate these problems by reducing and separating the conflict points through various techniques such as creating dedicated turn lanes, limiting the number of left-turn access points by installing medians, and promoting driveway consolidation. The discussion on different types of access management measures has highlighted the significant positive impacts on capacity, speed, and safety of roadways that have undergone some form of partial or full access control. There are also benefits in the form of improved pedestrian safety, better aesthetic quality of the community, and significant environmental benefits.