Showing posts with label highway systems. Show all posts
Showing posts with label highway systems. Show all posts
Public Transportation and Urban Form - Part 2
Furthermore,
in the San Francisco case, proximity to stations had an adverse effect on
rehabilitation in and improvements to older neighborhoods. And, although
proximity to the system stimulated a net increase in new housing, much of this
was for single families in areas that earlier had been beyond reasonable
commuting distance to the two principal central business districts. The net
effect at these locations was dispersal and lower density land use. Also,
transit use has been disappointing; to date it accommodates only 5% of the peak
hour trips. This is not to say that transportation engineering systems cannot
be employed to affect urban form, but that to date knowledge of the many
influences and their effects are lacking so that outcomes cannot be predicted.
Substantially
reducing automobile use in favourite of transit will be a slow process, although it
may be hastened by energy and environmental concerns. Among useful steps that
can be taken is to preserve land corridors for projected transportationfacilities. This and similar actions calls for a high degree of cooperation
among governmental ogencies or their restructuring to get a unified approach to
decision making. To date this cooperation or restructuring is happening very
slowly. Furthermore, the planning scope must reach travel problems beyond the
close-in urban area. For example, the land-side movements to and from airports
have extremely high volumes and yet today are often poorly served by local
transportation. Finally, the influence of telecommunications,
which can drastically reduce the need for central-city travel, must be
carefully considered.
Systems for Route Transportation Designation
Practically all the major highways in the United States are marked with route- designation signs which are shown on maps prepared for motorists. This route- designation system is usually separate and distinct from that used for highway- management purposes, and the two should not be confused. In sum, the route- designation scheme for the United States is as follows:
INTERSTATE ROUTES
A numbering system, consistent nation¬wide, developed by AASHTO. North-south trending routes have odd numbers, with numbers increasing from west to east. East-west trending routes have even numbers, with numbers increasing from south to north. Signs are reflectorized and in full colours red, white, and blue.
UNITED STATES HIGHWAY ROUTES.
A numbering system, reasonably consistent nationwide, that overlaps portions of the federal-aid and state highway systems. Odd and even numbers are for north south and east west tending routes, respectively, as with the Interstate System. However, the numbering be¬gins in the east and north rather than west and south. The sign shape resembles a shield.
STATE HIGHWAY ROUTES. A numbering system for routes of some continuity within individual states. Each state has adopted a distinctive shape or pattern for its sign; for example, the Pennsylvania route marker resembles a keystone. Similar numbering schemes also have been developed by some local agencies.
SPECIAL DESIGNATIONS. At times, freeways or toll roads are given special designations to identify them more clearly in the minds of motorists. Examples are the New York Thruway, the Will Rogers Turnpike in Oklahoma, and the San Bernardino Freeway near Los Angeles, California. Such designations are an aid to those driving straight through but may confuse others w'ho are looking for specific destinations along the route. A related problem is that of the motorist who, unfamiliar with the road, has trouble identifying an intended turnoff. One plan is to indicate each turnoff with the name of a nearby community; another is to number them consecutively, or in relation to the miles from some beginning point.
State Highway Systems Transportation
In each state a system of roads has been designated by the legislature as a state highway system. Rural proportions of the total most important arteries; at the other they have assumed responsibility for almost all rural roads, including some with gravel or soil surfaces. It is common for rural state systems to incorporate the Interstate System, the federal-aid primary system and some routes from the federal-aid secondary system, and possibly other important highways as well. The combined length of the 50 state highway systems is 704,000 mi rural and 87,000 mi urban. ADT, including In-terstate System traffic, was roughly 2300 rural and 22,000 urban in 1978.
Only 12% of the urban mileage is on state highway systems. This is a continuation of the viewpoint from early days that streets are primarily a local responsibility.
County and Township Roads
In the 3000 counties of the United States there are 1.7 million mi of rural roads not in the state highway systems. A relatively small portion of this mileage is in the federal-aid secondary system. These are commonly classified as local rural roads, although in large urban areas, county roads may include major traffic arteries. In addition, there are some 17,000 townships and other jurisdictions that have distinct and separate rural road systems. Their mileage totals 519,000.
The various secondary, federal, and local rural road systems constitute 86% of the nation's road mileage, the vehicle- miles accumulated on them are less than one-fourth the total. Their function is largely that of land service, and traffic averages about 110 vehicles per day or about one vehicle every three minutes in the peak hour. Many carry far lower volumes. In less populated areas, improvements are often of a low' order; nationwide, some 651,000 mi are primitive or are only graded and drained. Land- use studies have revealed that many rural agencies have mileage in excess of that needed for proper land service and many are making efforts to abandon some of it.
Urban Streets
As noted, some important urban streets have been incorporated into the federal- aid or state highway systems. There remains 607,000 mi of streets and alleys in
18,0 urban communities that are under local control. Some serve primarily as arteries for local traffic and others mainly provide access to property. Traffic on them varies widely, but averages about 800 vehicles per day. Volume on purely residential streets would be far lower.
INTRODUCTION HIGHWAY TRANSPORTATION SYSTEMS
By legislative acts in the several states, roads and streets
have been separated into "systems." Authority over each of these
systems rests with an appropriate legislative or administrative body. It, in
turn, makes provision for the planning, design, construction, maintenance, and
operation of its particular group of highways. Table 2-1 classifies the mileage
of roads and streets in the United States by states and by systems.
In the United States, 85% of the highway mileage, some
3,190,000 mi, lies in rural areas. Its distribution over the country varies
with population and development; it ranges, excluding Alaska, from 0.40 mi of
road per square mile for Arizona to 4.2 mi of road per square mile for New
Jersey. Before 1890 this rural mileage was without system or classification.
Responsibility for its establishment and upkeep was in the hands of local
government; counties, town-ships, and towns took care of the roads. In general
their condition was poor.
New Jersey, in 1891, first initiated state aid for rural
roads, and by 1910 about half the states had set up state highway departments
with varying degrees of authority. Finally, the Federal-Aid Act of 1916, which
made participation in federal aid contingent on having a state highway
organization, caused the remaining states to establish departments; in similar
manner, the Federal-Aid Highway Act of 1921 (to be discussed subsequently)
brought the concept of highway systems for rural roads to all the states.
The distinctions between highway systems, if merely "on
paper/' would be unimportant. However, they reach far deeper, particularly in
the area of finance. Funds for highways are appropriated from designated
sources to specific systems. Thus, funds for improvements to one system may be
quite readily available while those for another are extremely scarce.
Figure 2—1 offers comparisons for mileages and traffic
volumes among different highway systems. The contrast is particularly marked
between the Interstate System and principal arterials with low mileage and
heavy use on the one hand, and local roads and streets for which the reverse is
true.
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