1、 CHAPTER 1 HYDRAULIC CONSIDERATIONS IN HIGHWAY PLANNING AND LOCATION 2007 by the American Association of State Highway and Transportation Officials. 2007 by the American Association of State Highway and Transportation Officials.CHAPTER 1 TABLE OF CONTENTS 1.1 INTRODUCTION. 1-1 1.2 GENERAL CONSIDERAT
2、IONS . 1-1 1.2.1 Definitions . 1-2 1.2.1.1 Planning . 1-2 1.2.1.2 Location . 1-2 1.2.2 Coordination 1-3 1.2.2.1 Coordination within the Transportation Agency 1-4 1.2.2.2 Coordination with Other Agencies. 1-4 1.2.2.3 Public Involvement 1-5 1.2.3 Legal Considerations .1-5 1.2.3.1 Permits . 1-6 1.2.3.2
3、 Regulations. 1-6 1.2.3.3 Laws. 1-7 1.2.3.4 Federal Emergency Management Agency . 1-7 1.2.4 Related Considerations 1-8 1.2.4.1 Design-Related Considerations 1-9 1.2.4.2 Construction-Related Considerations. 1-9 1.2.4.3 Maintenance-Related Considerations. 1-10 1.2.5 Environmental Considerations. 1-10
4、1.2.5.1 Water Quality. 1-10 1.2.5.2 Fish and Wildlife 1-11 1.2.5.3 Other Environmental Considerations. 1-12 1.3 SPECIFIC CONSIDERATIONS. 1-12 1.3.1 Stream Geomorphology . 1-13 1.3.1.1 Types of Streams 1-13 1.3.1.1.1 Braided Streams . 1-14 1.3.1.1.2 Straight Streams . 1-14 1.3.1.1.3 Meandering Stream
5、s 1-14 1.3.1.2 Islands 1-15 1.3.1.3 Delta Formations and Alluvial Fans 1-16 1.3.1.4 Aggradation and Degradation 1-16 1.3.2 Highway Alignment. 1-17 1.3.2.1 Horizontal Alignment 1-17 1.3.2.1.1 Existing Alignment 1-17 1.3.2.1.2 New Location or Relocation 1-18 1.3.2.2 Vertical Alignment. 1-18 1.3.3 Loca
6、tion of Stream Crossings 1-19 1.3.3.1 Physical Considerations . 1-19 1.3.3.1.1 Confluences 1-19 1.3.3.1.2 Tidal Areas. 1-20 2007 by the American Association of State Highway and Transportation Officials.1-iv Highway Drainage Guidelines 1.3.3.2 Land Use Considerations1-20 1.3.3.3 Type of Structure1-2
7、1 1.3.4 Encroachments .1-21 1.3.4.1 Longitudinal Encroachments1-21 1.3.4.2 Transverse Encroachments .1-23 1.3.5 Ice and Debris.1-24 1.3.6 Location of Storm Drainage Facilities1-24 1.3.7 Location of Utilities1-25 1.3.8 Floodplain Development and Use 1-26 1.4 PRELIMINARY SURVEYS 1-27 1.4.1 Topographic
8、 Data .1-27 1.4.2 Channel Characteristics 1-28 1.4.3 Hydrologic Data .1-28 1.4.3.1 Basin Characteristics 1-28 1.4.3.2 Precipitation1-29 1.4.3.3 Flood Data 1-29 1.4.3.4 Highwater Information .1-29 1.4.3.5 Existing Structures1-30 1.4.4 Environmental Data1-30 1.4.4.1 Fish and Wildlife 1-30 1.4.4.2 Vege
9、tation.1-30 1.4.4.3 Water Quality .1-31 1.4.5 Field Review.1-31 1.5 PRELIMINARY HYDRAULIC REPORTS.1-32 1.6 REFERENCES 1-32 APPENDIX 1A 1-34 2007 by the American Association of State Highway and Transportation Officials.Chapter 1 Hydraulic Considerations in Highway Planning and Location 1.1 INTRODUCT
10、ION The planning and locating of highway facilities are the first steps in a challenging process of providing a safe and efficient transportation system. Hydrologic and hydraulic requirements are among the facets that must be considered during the early phases of the design process. Water and its re
11、lated resources are important considerations in the planning and locating of highways and their appurtenant facilities. Although historically only major drainage features (e.g., large rivers, environmentally sensitive areas) have been considered during these early stages, the overall drainage soluti
12、on must be visualized and studied so that substantial design and construction changes are not required later. The possible effects that highway construction may have on existing drainage patterns, river characteristics, potential flood hazards, and the environment in general, and the effects the riv
13、er and other water features may have on the highway, should be considered at this time. Hydrologic and hydraulic specialists must be actively involved during the initial project phases to ensure that proper consideration is being given to drainage aspects. This involvement should include participati
14、on during the highway location selection phase. Early input from these specialists will result in a better design, both hydraulically and economically. It must be emphasized that early studies are not comprehensive, detailed, technical designs. Rather, most are cursory studies to consider obvious dr
15、ainage-related problems that may be encountered or created and what type of data needs to be collected for evaluation of possible impacts. The degree and extent of preliminary hydraulic studies should be proportionate with the cost and scope of the project and the perceived flood hazards that may be
16、 encountered. This chapter presents a comprehensive overview of possible considerations in the planning and locating of a highway. 1.2 GENERAL CONSIDERATIONS There are many tasks and requirements that must be considered during the early phases of project development. Coordination between the various
17、 divisions of the transportation agency that may be involved with the project must be established. Notification of proposed projects must be made to other agencies and the public. The permits and regulations applicable to the project should be identified as soon as possible. Often, project delays ar
18、e due to the legal process. Problems that may arise during design, construction, or maintenance should be considered. In addition, environmental data needs should be determined. 2007 by the American Association of State Highway and Transportation Officials.Highway Drainage Guidelines 1-2 These, and
19、other considerations, cannot always be separate items that will be performed during the planning phase or during the location phase. Sometimes, considerations will occur during planning, while at other times those same considerations will occur during the locating of the highway. Often, there will b
20、e overlap, and sometimes the separation between the phases will be so indistinct that it will be difficult to determine in which phase the consideration should be addressed. Even so, it is helpful to understand what items are usually considered during each phase, especially because planning and loca
21、tion are such commonly used and misunderstood terms. 1.2.1 Definitions Different transportation agencies have various definitions of planning and location. What one State or agency feels is a planning function may be performed during the location phase in another. This AASHTO guideline will use the
22、definitions of planning and location as given in A Policy on Geometric Design of Highways and Streets, 2004 (1).11.2.1.1 Planning AASHTO, in A Policy on Geometric Design of Highways and Streets, 2004 (1) defines planning as the process that “includes the conduct of inventories, the preparation of ma
23、thematical models, the forecasting of economic and demographic growth, the development and evaluation of alternative transportation systems, the advising of those who will implement the selected plan, and the surveillance and reappraisal of the planning process as a continuing function.” During the
24、planning process, the hydraulics engineer will be principally involved in the conduct of hydraulic inventories, such as: river basins; wetlands; water supplies; dams; bridges; past flood events; and water, sewer, and storm drains. Such inventories should facilitate better hydraulic studies during th
25、e design phase. 1.2.1.2 Location The AASHTO definition of location activity details what specifically takes place during this phase: Location activity generally takes place after transportation planning and prior to highway design, but blends into both. The highway location should satisfy both the b
26、road goals of the transportation system and the local goals of the immediate environs. The usual steps followed in accomplishing location studies are: 1 Numbers in parentheses refer to publications in “References” (Section 1.6). 2007 by the American Association of State Highway and Transportation Of
27、ficials.Hydraulic Considerations in Highway Planning and Location 1-3(1) Determine broad route requirements; i.e., type of highway needed, control points. (2) Select corridors and identify all major alternatives. (3) Examine planning reports and conduct preliminary surveys to gather information on p
28、opulation densities and trends, land use development, travel patterns and trends, and economic, social, and environmental conditions that should be considered in selecting alternative highway locations. (4) Prepare preliminary plan and profile layouts for each alternative route so that cost estimate
29、s can be made and construction feasibility can be tested. (5) Evaluate alternatives to see which are worthy of further study and development. (6) Proceed with more complete location studies on the acceptable alternatives. (7) Determine and evaluate the economic and environmental effects of each alte
30、rnative. (8) Prepare the route location report as an aid to the decision maker. (9) Conduct a corridor public hearing. It may precede or follow the submission of the route location report. (10) Review by decision maker to determine which alternative route should be advanced to the design stage. The
31、participation of the hydraulics engineer during the location phase should ensure the proper consideration of the many items that affect or are affected by drainage. These specific items that may need to be considered are covered in detail in the following sections of this chapter. 1.2.2 Coordination
32、 There are two types of coordination during the preliminary phases of a highway project. One is to obtain or provide information. The hydraulics engineer needs to know the general scope of the highway project and possible plans of other agencies and developers regarding future projects in the waters
33、hed through which the highway may pass. Information from the general public is useful, most particularly in the area of historical flood data. Information should be shared with regulatory agencies that issue permits or implement decisions that could affect the project. The hydraulics engineer should
34、 also provide appropriate data to these same sources, which is used to support any important hydraulic recommendations. The second type of coordination can provide substantial economic savings. This is the coordination or combination of a highway project with a non-highway project. A joint project,
35、such as a stormwater retention facility, can result in savings and other benefits for all parties involved, usually by eliminating the duplication of certain functions or by the simultaneous construction of projects. Facilities can sometimes be combined or integrated resulting in the need for less r
36、ight-of-way. 2007 by the American Association of State Highway and Transportation Officials.Highway Drainage Guidelines 1-4 1.2.2.1 Coordination within the Transportation Agency Early coordination between the planning and location engineers and the hydraulics engineer may help minimize potential pro
37、blems. Planning and location engineers can be alerted to unstable reaches of streams that may be avoided by slight changes in the alignment. Critical areas sensitive to flooding should be identified. Estimated structure sizes and costs can be provided. Expensive bridges or extensive encroachments on
38、 sensitive environmental areas may provide cause to modify the alignment. It is important, therefore, for the hydraulics engineer to become involved not only with the alignments to be studied, but with the corridors as well. There may be sections to avoid within a watershed (e.g., wetlands, water su
39、pplies, sewage works, environmentally sensitive areas). There may also be times when entire watersheds should be avoided. 1.2.2.2 Coordination with Other Agencies The hydraulics engineer should be involved in the coordination process with other agencies that may have water resource data. These Feder
40、al, State, and local agencies have a wealth of information useful to anyone involved in hydraulics or hydrology. This coordination is necessary to find out about plans for water-related projects within the project area and to inform other agencies about the highway. Because these often are the agenc
41、ies who will issue the various permits for the project, concerns can be more easily worked out at this stage. Often, minor changes can be agreed upon by both agencies without considerable paperwork and formal meetings. It is important for the hydraulics engineer, therefore, to not only coordinate wi
42、th these agencies, but also to establish a good working relationship with them. Some agencies that may be involved or have interest in a project include: Federal Army Corps of Engineers Bureau of Reclamation Bureau of Land Management Bureau of Indian Affairs Coast Guard Environmental Protection Agen
43、cy Federal Emergency Management Agency Fish and Wildlife Service Forest Service Geological Survey International Boundary and Water Commission National Marine Fisheries Service National Oceanic and Atmospheric Administration Natural Resources Conservation Service Tennessee Valley Authority 2007 by th
44、e American Association of State Highway and Transportation Officials.Hydraulic Considerations in Highway Planning and Location 1-5State Environmental Protection Agencies Coastal Zone Management Agencies Planning Agencies Fish and Game Agencies Floodplain Management Agencies Water Resource Agencies L
45、ocal Drainage Districts Flood Control Districts Irrigation Districts Municipal Governments Indian Councils Planning Districts Regional Water Quality Control Boards Watershed Districts Other Historical Commissions Private Citizens Private Industry River Basin Compacts, Commissions, Committees, and Au
46、thorities Governmental Societies Academic Institutions 1.2.2.3 Public Involvement Much drainage information can be obtained by contacting and coordinating with the general public. Interviews with local residents concerning the knowledge of past hydrologic events can be helpful, though the recollecti
47、ons of more than just one person should be obtained. Although local ordinances generally do not have the force of law for State agencies, coordination with the local community or jurisdiction is always desirable and recommended. Community offices may have histories that could yield valuable informat
48、ion of past flooding events or other drainage or water resource problems. Public involvement is not only the gaining of information from others, but the sharing of it as well. Information on the project should be presented during the early stages of development so that the public will be knowledgeab
49、le of the agencys plans and not rely on rumors that may originate from other sources. Those providing information must be careful though to emphasize its preliminary nature. 1.2.3 Legal Considerations Among the many considerations to be made in selecting highway route locations are those regarding the various legal requirements and implications of the construction. The hydraulics engineer must have an understanding of those as they pertain to drainage and water law at the national, S
