6 CHAPTER 1 INTRODUCTION TOTRAFFIC ENGINEERING vides the traveler ices for all kinds of 1.2.3 People,Goods,and Vehicles trips,educational trips,and even the commute to work. The most common unit used by the traffic engineer is The range of available choices is enabled by having an vehicles."Highway systems are planned,designed.and nent of the Accessibility is a major factor in the value of land. goods that occupy vehicles epeh When land can be accessed by many travelers from many potent tial origins,it is more able for develop- therefore,more va way to its persor ties is a major factor determining its Mobility and accessibility may also refer to dif- pacity of 2,000vehicles per hour(veh/h).If each vehicle ferent portions of a typical trip.Mobility focuses on carries one person,the lane has a capacity of 2,000per through porti on of fected by sons/hour as well.If the rage car occupancy is in tak 4000 ns/hour.If the l quires the ability to make a transfer from the trans established san eusive bus lane the vehicle-capac portation system to the particular land parcel on which ty might be reduced to 1,000veh/h due to the larger size the desired eAcesibli. and poorer operat ng characterist s of buses a sit es. whic pared Howev s carries 5 o As is discussed in Chapter 3.most transportation The efficient movement of goods is also vital to the systems are structured to separate mobility and access general economy of the nation.T he benefits of centralized often compete anc e no of varous products are possibl ded by way s and finisho distributed throughout the nation and the world for con local street networks sumption.While long-distance shipment of goods an ccess facilities which serve only raw mate als is ofte by ter,rall,or al ough v es(m IIy most otne es of hig the local rally takes place on a truck using the highway s vehicles entering and leaving off-street parking via driveways,buses stopping to pick up or discharge pas that allow trucks to be loaded a s,tru s),r on to uougn a on the other hand.tends to male such ac functions more dangerous. A good transportation system must provide for othmobility nd ity and should eople and goods not vehicles
6 CHAPTER 1 INTRODUCTION TO TRAFFIC ENGINEERING provides the traveler with many choices for all kinds of trip purposes, including recreational trips, medical trips, educational trips, and even the commute to work. The range of available choices is enabled by having an effective transportation network that connects to many alternative trip destinations within a reasonable time, with relative ease, and at reasonable cost. Accessibility is a major factor in the value of land. When land can be accessed by many travelers from many potential origins, it is more desirable for development and, therefore, more valuable. Thus, proximity of land to major highways and public transportation facilities is a major factor determining its value. Mobility and accessibility may also refer to different portions of a typical trip. Mobility focuses on the through portion of trips and is most affected by the effectiveness of through facilities that take a traveler from one general area to another. Accessibility requires the ability to make a transfer from the transportation system to the particular land parcel on which the desired activity is taking place. Accessibility, therefore, relies heavily on transfer facilities, which include parking for vehicles, public transit stops, and loading zones. As is discussed in Chapter 3, most transportation systems are structured to separate mobility and access functions, as the two functions often compete and are not necessarily compatible. In highway systems, mobility is provided by high-type facilities, such as freeways, expressways, and primary and secondary arterials. Accessibility is generally provided by local street networks. Except for limited-access facilities, which serve only through vehicles (mobility), most other classes of highway serve both functions to some degree. Access maneuvers, however (e.g., parking and unparking a vehicle, vehicles entering and leaving off-street parking via driveways, buses stopping to pick up or discharge passengers, trucks stopped to load and/or unload goods), retard the progress of through traffic. High-speed through traffic, on the other hand, tends to male such access functions more dangerous. A good transportation system must provide for both mobility and accessibility and should be designed to separate the functions to the extent possible to ensure both safety and efficiency. 1.2.3 People, Goods, and Vehicles The most common unit used by the traffic engineer is “vehicles.” Highway systems are planned, designed, and operated to move vehicles safely and efficiently from place to place. Yet the movement of vehicles is not the objective; the goal is the movement of the people and goods that occupy vehicles. Modern traffic engineering now focuses more on people and goods. While lanes must be added to a freeway to increase its capacity to carry vehicles, its personcapacity can be increased by increasing the average vehicle occupancy. Consider a freeway lane with a capacity of 2,000 vehicles per hour (veh/h). If each vehicle carries one person, the lane has a capacity of 2,000 personshour as well. If the average car occupancy is increased to 2.0 persons/vehicle, the capacity in terms of people is doubled to 4,000 personshour. If the lane were established as an exclusive bus lane, the vehicle-capacity might be reduced to 1,000 vehh due to the larger size and poorer operating characteristics of buses as compared with automobiles. However, if each bus carries 50 passengers, the people-capacity of the lane is increased to 50,000 persons per hour. The efficient movement of goods is also vital to the general economy of the nation. The benefits of centralized and specialized production of various products are possible only if raw materials can be efficiently shpped to manufacturing sites and finished products can be efficiently distributed throughout the nation and the world for consumption. Whle long-distance shipment of goods and raw materials is often accomplished by water, rail, or air transportation, the final leg of the trip to deliver a good to the local store or the home of an individual consumer generally takes place on a truck using the highway system. Part of the accessibility function is the provision of facilities that allow trucks to be loaded and unloaded with minimal disruption to through traffic and the accessibility of people to a given site. The medium of all highway transportation is the vehicle. The design, operation, and control of highway systems relies heavily on the characteristics of the vehicle and of the driver. In the final analysis, however, the objective is to move people and goods, not vehicles
1.3 HIGHWAY LEGISLATION AND HISTORY IN THE UNITED STATES 1.2.4 Transportation Modes term"tumpike,"often used to describe toll roadways in modem times. ways and ere are oine dmportan The National Pike ational regional and local tra ne work.Table 1.1 provides a comprehensive listing of f the f berland Road,"this facility stretched for 800 miles from anumber of wa in of higl tems.Highway access to rail and air terminals is critical od deal of the orign route is owa portion of U.S. to their effectiveness,as is the design of specific transfer Route 40. on,pa Highwaysas a States'Right the expertise of the traffic engineer. t in the United Moreover,the effective integration of multimodal ult of ar transportation systems is a major goal in maximizing ef- 1832 Supreme Court case brought by the administration 怎randmniniig6osasociaedwhaloms of President Andrew Jackson.A major proponent of states'rights,the Jackson Administration petitioned the ngthat the not spec 1.3 Highway Legislation and History in the United States functions:they were.therefore.the responsibility of the individual states.The Supreme Court upheld this posi sen时b装&ge t of higl ns in the United tranportation and nd highways was forevermore assigned and regulates much of this activity.Key historical and leg- slative actions are discussed in the sections that follow The Governmental Context 1.3.1 The National Pike and the States' If the planning.design.construction.maintenance.and Rights Issue operation of highway systems is a state responsibility. for example,th thro S,roadswcrclitcmorcthantrailsclearcd nsportat on and plorers.Private roadways began to ear in the latte Adm of the 1700s.These roadways ranged in quality and length these processes? andothers from cleared trails to plank roadways.They were built by The federal government asserts its overall control private ners,and r their use of highway systems through the power of the purse ng for the construction ing stake,referred to as a"pike."When the fee was col highway and other transportation systems.States are not ected,the pike would be swiveled or tumed,allo ing the required to follow federal mandates and standards but traveler to proceed.This early process gave birth to the must do so to qualify for federal funding of projects
1.3 HIGH WAY LEGISLATION AND HISTORY IN THE UNITED STATES 7 1.2.4 Transportation Modes While the traffic engineer deals primarily with highways and highway vehicles, there are other important transportation systems that must be integrated into a cohesive national, regional, and local transportation network. Table 1.1 provides a comprehensive listing of various transportation modes and their principal uses. The traffic engineer deals with all of these modes in a number of ways. All over-the-road modes-automobile, bus transit, trucking-are principal users of highway systems. Highway access to rail and air terminals is critical to their effectiveness, as is the design of specific transfer facilities foir both people and freight. General access, internal circulation, parlung, pedestrian areas, and terminals for both people and freight are all projects requiring the expertis’e of the traffic engineer. Moreover, the effective integration of multimodal transportation systems is a major goal in maximizing efficiency and minimizing costs associated with all forms of travel. 1.3 Highway Legislation and History in the United States The development of highway systems in the United States is strongly tied to federal legislation that supports and regulates much of this activity. Key historical and legislative acti’ons are discussed in the sections that follow. 1.3.1 The National Pike and the States’ Rights Issue Before the 18OOs, roads were little more than trails cleared through the wilderness by adventurous travelers and explorers. F’rivate roadways began to appear in the latter part of the 1700s. These roadways ranged in quality and length from cleared trails to plank roadways. They were built by private owners, and fees were charged for their use. At points where fees were to be collected, a barrier usually consisting olf a single crossbar was mounted on a swiveling stake, referred to as a “pike.” When the fee was collected, the pike would be swiveled or turned, allowing the traveler to proceed. This early process gave birth to the term “turnpike,” often used to describe toll roadways in modern times. The National Pike In 1811, the construction of the first national roadway was begun under the direct supervision of the federal government. Known as the “national pike” or the “Cumberland Road,” this facility stretched for 800 miles from Cumberland MD in the east, to Vandalia IL in the west. A combination of unpaved and plank sections, it was finally completed in 1852 at a total cost of $6.8 million. A good deal of the original route is now a portion of U.S. Route 40. Highways as a States’ Right The course of highway development in the United States, however, was forever changed as a result of an 1832 Supreme Court case brought by the administration of President Andrew Jackson. A major proponent of states’ rights, the Jackson Administration petitioned the court claiming that the U.S. constitution did not specifically define transportation and roadways as federal functions; they were, therefore, the responsibility of the individual states. The Supreme Court upheld this position, and the principal administrative responsibility for transportation and highways was forevermore assigned to state governments. The Governmental Context If the planning, design, construction, maintenance, and operation of highway systems is a state responsibility, what is the role of federal agencies-for example, the U.S. Department of Transportation and its components, such as the Federal Highway Administration, the National Highway Safety Administration, and others in these processes? The federal government asserts its overall control of highway systems through the power of the purse strings. The federal government provides massive funding for the construction, maintenance, and operation of highway and other transportation systems. States are not required to follow federal mandates and standards but must do so to qualify for federal funding of projects
CHAPTER 1 INTRODUCTION TO TRAFFIC ENGINEERING Table 1.1:Transportation Modes Approximate Range of Mode Typical Function Capacities Urban People-Transportation System Automobile m 1-6persons/vehicle;approx. Taxi/For-Hire Vehicles Local Bus Transit with many stops. 5 000nersons/h/route Express Bus Transit Public transportation along fixed routes 40-50 persons/bus (no standees); on a fixed schedule;higher speed with canacity limited by schedule few intermediate stops. Para-transit Public transportation with flexible Variable seating capacity depends upon vehicle design; of a Light Rail mm 1-2 120per to 15.000 Heavy Rail He ns/car depending on seating configuration and standees on fully separated rights-of-way in up to 60,000persons per track. tunnels,on elevated structures,or on the surface. Waterborne public transportation for s along fixed routes eth fery design irinPeopteTmnsportaton automobile Private transportation available on Same as urban automobile demand for all trip purposes. Intercity Bus Public transportation along a fixed 40-50 passengers per bus: intercity route on a fixed(and usually schedules highly variable limited)schedule.Provides service to a central terminal location in each city Rangescite represent typical values,not the full range of. (Continued)
8 CHAPTER 1 INTRODUCTION TO TRAFFIC ENGINEERING Table 1.1: Transportation Modes Approximate Range of Mode Typical Function Capacities* Urban People-Transportation Systems Automobile Private personal transportation; 1-6 persondvehicle; approx. available on demand for all trips. Taxi/For-Hire Vehicles Private or shared personal transportation; available by prearrangement or on call. Local Bus Transit Public transportation along fixed 40-70 persons/bus; capacity routes on a fixed schedule; low speed with many stops. 5,000 personsklroute. Public transportation along fixed routes on a fixed schedule; higher speed with few intermediate stops. routing and schedules, usually available on call. Rail service using 1-2 car units along fixed routes with fixed schedules. Heavy rail vehicles in multi-car trains along fixed routes with fixed schedules on fully separated rights-of-way in tunnels, on elevated structures, or on the surface. people and vehicles along fixed routes on fixed schedules. 2,000 vehh per freeway lane; 400-700 veNh per arterial lane. 1-6 persons/vehicle; total capacity limited by availability. limited by schedule; usually 100- 40-50 persons/bus (no standees); capacity limited by schedule. Express Bus Transit Para-transit Public transportation with flexible Variable seating capacity depends upon vehicle design; total capacity dependent on number of available vehicles. 80-120 persons/car; up to 15,000 personskdroute. 150-300 persons/car depending on seating configuration and standees; up to 60,000 persons per track. Light Rail Heavy Rail Ferry Waterborne public transportation for Highly variable with ferry design and schedule. Intercity People-Transportation Systems Automobile Private transportation available on Same as urban automobile. demand for all trip purposes. Public transportation along a fixed intercity route on a fixed (and usually limited) schedule. Provides service to Intercity Bus 40-50 passengers per bus; schedules highly variable. a central terminal location in each city. -Ranges cited represent typical values, not the full range of possibilities. (Continued)
1.3 HIGHWAY LEGISLATION AND HISTORY IN THE UNITED STATES 9 Table 1.1:Transportation Modes (Contimed) Mode Typical Function Intercity People-Transportation Systems(Cont Railroad Passenger intercity-rail service on 500-1,000passengers per train, fixed routes on a fixed (and usually Air From 3 4 passenge on fixed routes and fixed schedules Water Passenger ship service often associated with on- Long-Haul Trucks Single-,double-,and triple tractor-traile com Local Trucks Smaller trucks provide distribution of goods Hauling capacity of all freight and services throughout urban areas. modes varies widely with the Railroad ntercity haulage of bulk commodities design of the vehicle (or pipeline) Water ntecwnaulaeohk shins and bargcs Air Freight International and intercity haulage of small and moderately sized parcels and/or time. sensitive and/or high-value commodities where high cost is not a disincentive. Pipelines sible Ranges cited represent typical values,not the full range of possibilities
1.3 HIGHWAY LEGISLATION AND HISTORY IN THE UNITED STATES 9 Table 1.1: Transportation Modes (Continued) Approximate Range of Mode Typical Function Capacities* Intercity People-Transportation Systems (Cont.) Railroad Passenger intercity-rail service on fixed routes on a fixed (and usually limited) schedule. Provides service to a central terminal location or locations within each city. 500-1,000 passengers per train, depending upon configuration; schedules highly variable. Air A variety of air-passenger services from small commuter planes to jumbo jets on fixed routes and fixed schedules. From 3-4 passengers to 500 passengers per aircraft, depending upon size and configuration. Schedules depend upon destination and are highly variable. Ship capacity highly variable from several hundred to 3,500 passengers; schedules often extremely limited. Water Passenger ship service often associated with on-board vacation packages on fixed routes and schedules. Urban and Intercity Freight Transportation Long-Haul Trucks Single-, double-, and triple tractor-trailer combinations and large single-unit trucks provide over-the-road intercity service, by arrangement. Smaller trucks provide distribution of goods and services throughout urban areas. Intercity haulage of bulk commodities with some local distribution to locations with rail sidings. schedule availability. International and intercity haulage of bulk commodities on a variety of container ships and barges. International and intercity haulage of small and moderately sized parcels and/or timesensitive and/or high-value commodities where high cost is not a disincentive. Continuous flow of fluid or gaseous commodities; intercity and local distribution networks possible. xRanges cited represent typical values, not the full range of possibilities. Local Trucks Railroad Hauling capacity of all freight modes varies widely with the design of the vehicle (or pipeline) and limitations on fleet size and Water Air Freight Pipelines
10 CHAPTER I INTRODUCTION TO TRAFFIC ENGINEERING that has the responsibility to control the intersection. guidelines and standards.As no state can afford to give Local organizations for highway functions range up this massive funding source,the federal government from a full highway or transportation department to local police to a single professional traffic or city en- major components: e m I rmee There are also a numbe state constitution grantshome rule"powers to any mu and Native American reservations. a population in exce 00,000pe Provision of funding ass istance in urrent federal-aid tra ing those on the state highway system. and followed to qualify for receipt of federal-aid 1.3.2 Key Legislative Milestones transportation funds. Federal-Aid Highway Act of 1916 4.Monitoring and enforcing c mpliance with fed eral standards and criteriaand the use offederal aid funds. struction by the states established the State govemments have the primary responsibility for the plar ion,ma nighways, 50%of the funding for c ays in for fe ut thr tate ment of portation or similar agency.States have: the ac ed ery two to five ars (with in creasing amounts dedicated).No major changes in fund- 1.Full responsibility For administration of high- ing formulas were forthcoming for a period of 40 years. way systems. 2.Full responsibility for the planni Federal-Aid Highway Act of 1934 construction.maintenance.and operation of ewing funding for the A-B-c Sv highway systems in conformance with applica- to 15%of federal-aid ble federal standards and guidelines. funds for planning studies and other investigations.It rep- 3.The right to delegate sibilities for loca sented the entry of the federal government into highway planning agencies. Local govemments Federal-Aid Highway Act of 1944 This act contained the initial authorization of what be- design,construction,maintenance,and control of local funds Often agencies is ava
10 CHAPTER 1 INTRODUCTION TO TRAFFIC ENGINEERING Thus, the federal government does not force a state to participate in federal-aid transportation programs. If it chooses to participate, however, it must follow federal guidelines and standards. As no state can afford to give up this massive funding source, the federal government imposes strong control of policy issues and standards. The federal role in highway systems has four major components: 1. 2. 3. 4. Direct responsibility for highway systems on federally owned lands, such as national parks and Native American reservations. Provision of funding assistance in accord with current federal-aid transportation legislation. Development of planning, design, and other relevant standards and guidelines that must be followed to qualify for receipt of federal-aid transportation funds. Monitoring and enforcing compliance with federal standards and criteria, and the use of federalaid funds. State governments have the primary responsibility for the planning, design, construction, maintenance, and operation of highway systems. These functions are generally carried out through a state department of transportation or similar agency. States have: 1. Full responsibility €or administration of highway systems. 2. Full responsibility for the planning, design, construction, maintenance, and operation of highway systems in conformance with applicable federal standards and guidelines. 3. The right to delegate responsibilities for local roadway systems to local jurisdictions or agencies. Local governments have general responsibility for local roadway systems as delegated in state law. In general, local governments are responsible for the planning, design, construction, maintenance, and control of local roadway systems. Often, assistance from state programs and agencies is available to local governments in ~ ~ ~~~~ fulfilling these functions. At intersections of state highways with local roadways, it is generally the state that has the responsibility to control the intersection. Local organizations for highway functions range from a full highway or transportation department to local police to a single professional traffic or city engineer. There are also a number of special situations across the United States. In New York State, for example, the state constitution grants “home rule” powers to any municipality with a population in excess of 1,000,000 people. Under this provision, New York City has full jurisdiction over all highways within its borders, including those on the state highway system. 1.3.2 Key Legislative Milestones Federal-Aid Highway Act of 191 6 The Federal-Aid Highway Act of 1916 was the first allocation of federal-aid highway funds for highway construction by the states. It established the “A-B-C System” of primary, secondary, and tertiary federal-aid highways, and provided 50% of the funding for construction of highways in this system. Revenues for federal aid were taken from the federal general fund, and the act was renewed every two to five years (with increasing amounts dedicated). No major changes in funding formulas were forthcoming for a period of 40 years. Federal-Aid Highway Act of 1934 In addition to renewing funding for the A-B-C System, this act authorized states to use up to 1.5% of federal-aid funds for planning studies and other investigations. It represented the entry of the federal government into highway planning. Federal-Aid Highway Act of 1944 This act contained the initial authorization of what became the National System of Interstate and Defense Highways. No appropriation of funds occurred, however, and the system was not initiated for another 12 years