Difference between road and street

ROADS AND STREETS

ROADS AND STREETS

INTRODUCTION

Engineering surveying methods utilized in the planning, design, and construction of roadways have changed rapidly in recent years. These changes provide more efficient and accurate surveys, particularly for large-scale projects.

This chapter addresses the planning and execution of engineering surveys for rural roads and urban arterial streets, including preliminary or reconnaissance surveys, design surveys, and construction surveys. The increasing public concern over environmental protection indicates further changes in surveys may be needed to provide information useful in preparing environmental assessments, as well as in project planning and design. Such changes must be carefully considered before any extensive field survey efforts are initiated.

Engineering surveying for a road or street improvement project generally begins with a preliminary or reconnaissance survey. This survey may also be called a corridor definition survey. It provides the topographic data in a broad corridor necessary for the investigation of alternate locations and alignments. The reconnaissance survey may be omitted in the design of urban arterial streets where location and alignment are largely dictated by the existing land use and street pattern. It should be noted in this respect, however, that good topographic and cadastral maps are essential to land subdivision design, which involves the location and configuration of collector and land access streets. If good topographic and cadastral maps are available at an adequate scale—1 in. = 200 ft (1:2,400) or larger—on an areawide basis, such maps will provide a better basis for the location studies than a special survey, and they will do so far more economically.

The next stage in project development requires a design survey. The design survey may be separated into horizontal and vertical control surveys; surveys for determining profiles and cross sections, topography, and drainage; right-of-way surveys; and surveys for such additional data as may be required for the design of a particular project.

After the design survey, project development will next require a construction survey. Construction surveys provide the horizontal and vertical control for construction, information required for calculation of final quantities, and data for development of as-built plans.

Comprehensive project planning for preliminary, design, and construction surveys results not only in an efficient survey program but, more importantly, in a plan which optimizes capital expenditures throughout project development. The engineering-manager must be fully cognizant of the importance survey information has in the design of roadway projects. Careful planning will minimize confusion and cost during actual construction by providing control throughout the construction period, and it will contribute to the efficient assembly of essential post-construction records.

PROJECT PLANNING FOR SURVEYS

A prerequisite for the sound development of a survey program is knowledge of the basic survey needs of the particular project involved and the alternative methods for meeting those needs. The engineering-manager must, therefore, be knowledgeable about engineering surveying, roadway design, and construction in order to develop the survey program.

The engineering-manager must see that all available survey data for the project area are assembled in readily usable form. These data may include existing topographic and cadastral maps, aerial photographs, photogrammetric products, horizontal and vertical control, and as-built plans of other projects in the area. The organizations responsible for roads and streets in a specific geographical area should maintain comprehensive files of survey information available for ready reference.

The type of roadway will determine the design procedures and the associated survey effort. Application of the latest design procedures developed for high-type (freeway and expressway) roadways may not be economical for low-type roads and streets for which far less sophisticated design procedures may be adequate.

The engineering-manager must also be knowledgeable of all available survey techniques and their applicability to each phase of the roadway design and construction process. Applications of new instruments and techniques, such as electronic distance measuring devices and computer-based photogrammetry, have substantial advantages but also certain disadvantages when used on simpler projects.

The engineering-manager must be knowledgeable of the latest federal, state, and local criteria which affect roadway construction. These may include important criteria for environmental impact assessment, citizen participation, and multi-governmental involvement which may have implications for survey, as well as design, efforts.

The engineering-manager must recognize construction requirements for accurate, well located survey control within the project area. Time, effort, and money are often needlessly expended due to inadequately monumented, inaccurate, or improperly placed control.

Lastly, the engineering-manager must be able to evaluate the survey effort required in terms of time and money. Whether for in-house use or for purposes of contractual agreements, this procedure is a necessary part of any survey planning effort. Should contractual agreements be required, the engineering-manager should be familiar with professionally sound contract-negotiation procedures and the applicability of such procedures to the engineering-surveying profession.

Based upon this knowledge and its application to a particular project, the engineering-manager should prepare a concise plan for the survey program. This report should include a project description; a statement of the survey objectives; a description of the available existing survey data; recommendations concerning the methods and order of survey execution; and time and cost estimates. Even though the detail of the survey plan reports may be expected to vary greatly between different road and street improvements, the preparation of the reports will ensure that the planning program was undertaken in a comprehensive manner.

PRELIMINARY OR RECONNAISSANCE SURVEYS

Location and alignment studies require that preliminary survey information be compiled within the project area. Generally, this information is compiled along a corridor on a small-scale strip map. Several means of developing the strip map, depending on the degree of completeness required, are available. The most common is to utilize aerial photographs and U.S. Geological Survey quadrangle maps. Since the primary purpose of the preliminary survey is to provide data for the study of a broad range of alternative locations and alignments, only some of which will be considered in greater depth and detail later in the project, maximum use of existing information is desirable.

Cost limitations are particularly important in the conduct of the preliminary surveys. Field work should be conducted only as necessary to supplement the existing data.

The preliminary survey should not only provide the information required for considering alternative alignments but should note critical information necessary for the subsequent location, design, and construction phases of the project. The type and extent of information collected should be responsive to socioeconomic and political issues and concerns, as well as strictly technical issues and concerns, since facility location may involve public participation in which community interests and environmental concerns are of great relevance. Needed, in addition to good topographic and hydrographic data, which may affect the horizontal and vertical location of the facility, are data on existing and proposed land use, soil and geologic conditions, surface and underground utilities, and real property boundary locations.

DESIGN SURVEYS

Design procedures for roads and streets normally necessitate that design plans be prepared at a scale of 1 in. = 100 ft (1:1,200) or larger so that design details and the conditions affecting such details may be indicated clearly on the drawings. Because of the wide variation in the character of road and street projects, extreme care must be exercised in the decision of what scale should be used. Use of drawings at a scale of 1 in. = 20 ft (1:240) is not unusual in urban areas where complex design considerations, including drainage and utilities systems, are involved. Two basic surveying methods are available, conventional field surveys and photogrammetric procedures.

The data required are similar to those required for the preliminary survey but in greater depth and detail. Extensive data on the details of existing features, such as curbs and gutters, driveway aprons, existing drainage facilities, utilities including sanitary sewers, water and gas mains, and power and communication cables, must be located to provide adequate data for design. For most projects requiring large areal coverage, photogrammetric or combination photogrammetric and field methods can be recommended.

Field Surveys

The first step in the conduct of field surveys should be establishing a system of monumented horizontal and vertical survey control in the project area. This survey control system will normally be provided through high-order traverse and level circuits. Good practice would dictate that the survey control be tied to the national geodetic datum by means of the state plane coordinate system.

The second step in the conduct of field surveys should be establishing monumented survey baselines for the project. In urban areas these baselines are generally located beyond the limits of existing roadways. In rural areas the baselines are generally made to correspond to the centerline of the proposed roadway. Profiles, cross sections, and relevant topographic features are then located relative to the baseline.

The type of detail and survey procedures for locating this detail will vary with the type of roadway. For a high-type, multiple-lane arterial roadway, profiles, cross sections, and topography are required. Information on the location, horizontal and vertical alignment, extent and elevation of the following features, among others, is required:

1.      Curbs, storm sewers including inlets and manholes, gutters, culverts, bridges, viaducts, paved areas, and sidewalks;

2.      Railway tracks, switch points, frogs, and signs and signals;

3.      Buildings;

4.      Major trees;

5.      Aerial transmission lines, towers and poles, street lights, traffic
signals, and traffic regulatory signs;

6.      Watercourses and related shorelands, floodlands and wetlands;

7.      Underground utilities, such as sanitary sewers and water mains,
telephone and electric power cables, manholes, and valves;

8.      Orchards and areas dedicated to the cultivation of fruits and vegetables and specialty crops;

9.      Property line corners, with particular attention to public right-of-way locations, fences, and other visible occupational lines.

On the other hand, a single-lane forest-access road might require only that an experienced location engineer establish a flagged grade line utilizing an Abney level and compass. Special attention should be directed to recording drainage details, including invert elevations of existing drainage facilities. Adequate detail must be obtained for connections between existing and proposed construction.

Construction baselines should be monumented. The monuments should be located outside the construction area so that baseline locations can be preserved throughout the construction period. Monument placement on the required right-of-way line is often desirable.

Certain special design requirements may call for additional survey effort and should, therefore, be considered in the survey program. Hydraulic design analyses require stream profiles and cross sections, together with pertinent information on the waterway openings of existing structures and special problems such as scour, and on the tributary drainage area affecting the proposed facilities. Core borings for roadway and structures require additional survey effort. Early consultations should be held with the soils, materials, and foundation engineers involved so that the survey effort can be designed to meet the needs of the geotechnical programs. Facilities such as the modification or extension of an existing structure, may necessitate additional detailed survey information, including detailed information on the existing structure.

If the facility location requires one or more major stream crossings, special crossing surveys may be required. These may have to be more accurate than the other types of surveys and include more elaborate forms of permanent monumented survey control. Special hydrographic surveys, current and flow measurements, and surveys locating subsurface geological features important to the structural stability of the crossing structure may be required. Data on the extent and characteristics of drainage areas will be required, together with historic information on flood stages. Information on tides, including ranges and currents, may be required for estuary and other marine crossings. Details of existing structures are essential if such structures are to be used as part of the project.

Photogrammetry

Conventional field survey methods have long been used for roadway improvement projects and are often still cost effective. Photogrammetric methods are, however, also available and should be investigated for their applicability to each project. Where photogrammetric methods are applicable, much field work can be eliminated.

Photogrammetric methods will economically provide, at an appropriate design scale and contour interval, design data for most roadways. The photogrammetric plan can help to eliminate the need for field surveys to collect profile, cross section, and topographic data. Photogrammetric mapping must be spot checked and may need to be augmented by field surveys. Depending upon the type of roadway, field surveys may be required to establish and monument horizontal and vertical survey control; to check topographic maps prepared by photogrammetric methods, as well as to supplement topographic details in areas of heavy tree cover; to establish, monument, and profile the baselines as a check and as a control for taking and plotting cross sections; and to provide topographic details required for the design of intersecting roadways, and to provide the data needed on the location and elevation of sewers and other underground utilities.

Care should be exercised in specifying photogrammetric mapping for a roadway improvement project. Only after identification of survey requirements and consultation with an experienced photogrammetrist should the project proceed.

Right-of-Way Considerations

The field surveys required for project right-of-way needs will be minimized by good survey planning. The preparation of right-of-way plats should be initiated by a careful research of deeds, tax maps, subdivision plats, existing right-of-way plats, and available property boundary line surveys and plats. The resulting information can be plotted on existing topographic maps to provide a basis for preparing the right-of-way plat. The proper location and orientation of real property ownership parcels may be significantly aided by the location of property corners during the conduct of the necessary topographic field surveys. Right-of-way plats are prepared to establish legal right-of-way lines and to determine areas for awarding property damages. Should any major discrepancies be found in parcel locations at this time, however, additional field survey and title investigation may be required.

After the proposed design is related to the right-of-way plats, needed property acquisition requirements can be determined. The acquisition may consist of fee simple purchase of the right-of-way, dedication, and purchase of easements for right-of-way and for areas required for construction.

The required areas are tied to the proposed construction either by coordinate geometry or field measurement. From this information, the legal description and areas of the proposed acquisition and parcel remainders can be developed.

Monumentation of required right-of-way lines is an established procedure used in roadway design and construction. In addition to providing definition of the right-of-way line, the monuments can also be used to reference the proposed construction from outside the construction area. Due to the extensive cost of placement, care must be exercised so that only necessary monuments are provided.

In summary, field surveys related to rights-of-way should be coordinated with the necessary topographic surveys; should include careful research of records relating to property corners which exist in the coverage area; should include special surveys to clarify discrepancies in parcel location; and should include the monumenting of right-of-way lines for project control and establishing legal rights-of-way boundaries for future use.

Even though the responsibility for compliance with legal requirements is in the hands of a responsible surveyor or engineer, the engineering-manager must be knowledgeable of these requirements in order to specify a comprehensive survey program for the project.

CONSTRUCTION SURVEYS

Construction surveys serve two basic purposes, construction control and provision of as-built information. Surveys for construction control include all survey work required for constructing the roadway project, including layout and continuous direction of operations, such as grading, paving, and erection, to assure proper horizontal and vertical location and alignment of the facility. As-built surveys include survey work necessary to determine final pay quantities and to prepare final plats showing the actual details of the completed construction.

Construction surveys are characterized by their dynamic nature. Establishing and reestablishing control to guide construction equipment and personnel and to ensure that all project elements are constructed in accordance with the plans and specifications are the continuous job of the engineer as construction progresses. Properly planned construction surveying control, as well as appropriate instrumentation—including total electronic stations and laser beam alignment instruments—will determine to a considerable extent the cost of the survey operations. This work should not be done by construction crews with no knowledge of coordinate geometry and without appropriate surveying engineering supervision.

Proper planning of the construction survey is of prime importance. Usually every critical design point or line that has to be laid out in areas of cut or fill should be accessible directly by distance and direction from at least three intervisible control points located outside the construction area. Traverse retracing to reestablish lost or obliterated markers is costly in both time and money and should be avoided.

For best results, and for avoiding costly mistakes, the preparation of a layout plan is recommended. Such a plan will show the locations—position coordinates—of all control points and the positions of the critical layout points, such as points of intersection, points of curvature and tangency, lowest and highest points, structural member positions and pier positions on a bridge, and the geometrical dimensions of all the project components. This will permit the surveying-engineer to readily compute in the field distances and directions between control and layout points. It helps avoid the need to interrupt construction operations to reestablish removed or disturbed survey markers.

The first step in the construction survey is to assure that all monuments are located outside the construction area and are adequately referenced so that they may be readily reestablished if disturbed or destroyed. This step must be taken prior to the start of construction, including the start of utility relocation in the construction area. The construction baselines are then monumented at required intervals. Subsequent construction survey efforts depend on the type of roadway, method of construction, and sequencing of construction work. For this reason, portions of the construction staking are sometimes included in the construction contract as the responsibility of the contractor with survey checks performed by the governing agency.

Bridge and viaduct construction requires special survey control. Because bridges and viaducts are usually constructed over water, wetland, or other inaccessible areas, control monuments usually cannot be located on, or even close to, the centerline of the proposed structure as would be the case for at grade pavements. Control must be located, wherever possible, on the abutments or on piles or dolphins parallel to the future bridge or viaduct. The two ends of the bridge or viaduct must be connected by precise horizontal and vertical surveys. Triangulation has been the classic method used to accomplish this, but with the development of electronic distance measuring devices, other more economical methods, such as traversing, have become available.

During bridge or viaduct erection, the positions of different structural elements—such as piers, abutments, beams, and columns—must be accurately established in the field. Construction equipment and temporary erection scaffolds may impair visibility and complicate this task. To facilitate the survey operation, the necessary control should be located outside the structure; point locations on the construction should then be established by angle intersection from two control stations, distance intersection from two control stations, or angle-distance intersection from one control station. The latter method is the more economical, requiring only one instrument and one line of sight. Reflectors can be taped on the extremes of the structural members and their positions established by electronic distance and angle measurement from one control station. Using a total station, coordinates of structural elements can be established.

During the roadway construction, field surveys may be employed to determine payment quantities, conformity with contract documents, and records of the final construction configuration. From these data, as-built plans are prepared to provide a permanent, accurate record of the final construction. Photogrammetric surveys before and after construction provide excellent bases for development of pay quantities and especially so in areas of rough terrain.

It is necessary to recognize, however, that construction surveys are an extremely important phase of the project and one that can cost the contractor or the owner a considerable amount of money if the survey is not accurate or all-inclusive. The as-built survey verifies that the facility was constructed in substantial compliance with the plans and specifications and, in a sense, constitutes a final audit. It is a survey frequently challenged in court and, when so challenged, must be authenticated by proper authority.

Right-of-way Monumentation and As-Built Survey

After the construction is finished, all property corners defining the right-of-way should be established and permanently monumented in accordance with the deeds of acquisition. In some cases fences may be erected for protection or for control of roadway access.

Because of variations authorized during construction to adapt the project to unforeseen conditions, the highway or street may not conform exactly to the design plans. In such cases the as-built surveys become particularly important. The result of such surveys is a set of plats reflecting the location of the right-of-way monuments and the new pavement, crossings, and other appurtenant structures as actually constructed. As-built plans should become part of the permanent records of the responsible agency.

MAPS TO BE PREPARED

The types of maps, and the scales and contour intervals required will vary in accordance with the survey purpose (reconnaissance, design, or construction), the amount of planimetric information required, and the topography of the project area. Map requirements will vary with the type of project: Local, that is, projects affecting a single community or sector of a community, such as an urban street project; or regional, that is, projects affecting several communities, such as a major highway. General projects do not entail special constraints and have minimal connections to existing facilities as, for example, typical rural highways and urban collector and land access streets. Critical projects have severe location restrictions and include projects such as major bridges and viaducts, underpasses and overpasses, and arterial streets through congested urban areas with many connections to existing facilities.

In general, the amount of planimetric detail, both above and below ground, is a function of the foregoing factors and the existing general land use in the project area, such as urban, suburban, rural agricultural, and rural rangeland. The map contour interval is also dependent on the topography of the project area. Tables 1, 2 and 3 indicate typical scale and contour interval values or ranges to use for maps for each type of project and phase.

REFERENCES

1.       American Society of Civil Engineers Manual No. 44, Highway and Bridge Surveys.

2.       Aguilar, Antonio M., “Cost Analysis for Aerial Surveying,” Photogrammetric Engineering, American Society for Photogrammetry, Vol. 33, No. 1, p. 81, January 1967.

3.       Aguilar, Antonio M., “Management Planning for Aerial Surveying,” Photogrammetric Engineering, American Society for Photogrammetry, Vol. 35, No. 10, p. 1047, October 1969.

4.       Aguilar, Antonio M., “Evaluation of Automatic Cartographic Systems for Engineering and Mapping Functions,” Journal of the Surveying and Mapping Division, American Society of Civil Engineers, Vol. 101, SU1, Proceedings Paper 11625, October 1975.

5.   Bezley, Jon S., “Modern Day Surveys for Highway Design,” Journal of the Surveying and Mapping Division, American Society of Civil Engineers, Vol. 96, SU1, Proceedings Paper 71976, April 1970.

6.       Elder, Edward K., “What Did He Buy? A Piece of Land or a Piece of Paper?”
American Congress of Surveying and Mapping, Proceedings Paper 73-264.

7.       Fant, Jesse E., “Survey Three Weeks, Study One Week,” American Congress
of Surveying and Mapping, Proceedings Paper 73-267.

8.       Keating, J. Bruce, “Orthophotomaps: A Base for Environmental Inventory Systems,” American Congress of Surveying and Mapping, Proceedings Paper 73-234.

9.       Shields, John M., “Project Planning,” American Congress of Surveying and
Mapping, Proceedings Paper 73-214.

10.       Wambach, William T., Jr., “Where Oh Where Is Your Right-of-Way Line?” Civil
Engineering, American Society of Civil Engineers, March 1973, p. 52.

11.       Watkins, Daniel J., “Surveying Responsibility of the Engineering Manager,” journal
of the Surveying and Mapping Division, American Society of Civil Engineers, Vol.
97, SU1, May 1971, p. 1.

12.       Woodward, Luis A., “Survey Project Planning,” Photogrammetric Engineering,
American Society for Photogrammetry, June 1970.

Table .—Typical Map Scale and Contour Interval for Paved Street and Highway Projects*

Preliminary or Reconnaissance				Design and Construction
Phase (1)	Local (2)	Regional (3)	Crossing Selection (4)	Critical (5)	General (6)
Land Use		Map Scale,	in feet per	nch
Industrial Urban Suburban Farmland Rangeland	100-  200 200-  400 400-  500 500-1,000 1,000-2,000	500-1,000 1,000-2,000 2,000-2,000 2,000-2,000 2,000-2,000	40- 50 50-100 100-200 200-400 200-500	10- 20 20- 40 40- 50 50-100 50-200	20- 40 40- 50 50-100 100-200 200-200
Topography		Contour I	nterval, in feet
Flat Gently Rolling Rolling Hilly Mountainous	0.5-1 1-2 2 5	1- 1 2- 2 2- 5 5-10	1- 2 2- 5 5-10 10-20 50	2-   5 5- 10 10- 20 20- 50 50-100	2-   5 5- 10 10- 20 20- 50 50-100

*Adapted from “Selection of Maps for Engineering and Planning,” Journal of Surveying and Mapping Division, SU1, American Society of Civil Engineers, Proceedings Paper 9073, July 1972.

Note: Ft × 0.305 = m; in. × 2.54 = cm

Table  .—Typical Map Scale and Contour Intervals for Temporary Road Projects*

Phase (1)	Preliminary or Reconnaissance	Design and Construction
	Local (2)	Critical (3)	General (4)
Land Use	Map Scale, in feet per inch
Industrial Urban Suburban Farmland Rangeland	200-  400 400-  500 500-1,000 1,000-2,000 2,000-2,000	20- 40 40- 50 50-100 100-200 200-200	40- 50 50-100 100-200 200-400 200-500
Topography	Contour Interval, in feet
Flat Gently rolling Rolling Hilly Mountainous	5- 10 10- 20 20- 50 50-100 100-200	1- 2 2- 5 5-10 10-20 50	1- 1 2- 2 2- 5 5-10

‘Adapted from: “Selection of Maps for Engineering and Planning,” Journal of Surveying and Mapping Division, SU1, American Society of Civil Engineers, Proceedings Paper 9073, July 1972.

Note: Ft × 0.305 = m; in. × 2.54 = cm