HIGHWAY ENGINEERING II

Transcription

1 HIGHWAY ENGINEERING II TRICKS AND PITFALLS - part two (For all highway engineers and designers) By: T. E. McLaughlin, PE Note: The materials used for this course include this document and several websites linked in this document. Only links marked with a red star are used in the course and test questions. A. INTRODUCTION This course is part two of a summary of highway engineering details and construction practices which are common to most highway projects. Examples from Florida practice are used in this course, but it is applicable to any State or region by considering local laws, regulations, and procedures. When you complete this course, continued from part one (not a requisite), you should have learned which standards apply to certain circumstances, additional traps and pitfalls which are common to highway design & construction, and how to avoid those problems. The course objective is to give engineers and designers a different perspective on their work, and explain why we do certain things in this area of professional practice. B. COURSE OBJECTIVES 1. Why does a State have more than one set of highway design standards? 2. How do those standards compare? [ County vs. State Minimum vs. new highway.] 3. What is the appropriate use of each set of standards? 4. Utilities in the right-of-way - how do you deal with them? 5. Permitting - What agencies are typically involved? How are utilities addressed? C. DISCLAIMER Page 1

2 Neither the author nor SunCam, Inc. is an attorney. If you need legal advice, consult a qualified attorney. D. WHY WOULD A STATE HAVE MORE THAN ONE SET OF HIGHWAY DESIGN STANDARDS? In Part One of this course series, we discussed why State Departments of Transportation have adopted some type of minimum highway design standards which are applicable to all roads, streets, and highways located within that respective state. In Part Two, we want to look at why there are or may be more than one set of design standards which may be applicable to a roadway under design (or at the commencement of design stage). EXAMPLE 1 - New highway design with state road designation, being funded by the State which owns the right-of-way. This highway will be a new road along previously undeveloped property. It will be designated as an arterial highway, have a 50 mph design speed, and will also be designated as an evacuation route, all determined by prior planning and public coordination. Your firm has received a design contract to provide design services, construction plans, bid documents, and bid evaluation services for the State Transportation Department. What design standards do you use? For purposes of this example, lets review the standards in effect in Florida. Go to the following web site and download only the 3 page Table of Contents from the 2008 Design Standards: [formerly Standard Indexes] By reviewing this table, you can see this book gives details of design and construction, but doesn t give design concepts or tell you how to design the road. Go to the following web site for the Florida 2008 Plans Preparation Manual (PPM) and download the Table of Contents: Page 2

3 The Plans Preparation Manual gives how to design information, omitting the construction details (such as inlet dimensions, reinforcing steel, and bolts for signs, etc.) which are found in the Design Standards book. However, they must be used together. The important point here is that your construction plans can refer to the Design Standards book for construction detail information, but can t refer a contractor to the Plans Preparation Manual to tell him how to complete the road design. Now lets review the Florida Greenbook (2007 edition). Go to the following web site and download the entire 2007 Florida Greenbook: The Introduction cites statutory references for the authority and applicability of this book. Keep this information in mind for future reference in the subsequent sections of this course. In the Introduction of the Greenbook, the text found in the center of page ii indicates: Standards established by this Manual are intended for use on all new construction projects off the state highway and federal aid systems. This text tells you that the Florida Green Book does NOT apply to our design example, EXAMPLE 1, above. So what design criteria apply? For this current example, the Plans Preparation Manual is the primary source of design information, since the highway under design is in the state highway system. Now let s review clear zone or clear recovery area for the design example, using a 50 mph design speed. Go to the following web site and download Chapters Two and Four of the 2008 Plans Preparation Manual: [updated 2008] Page 3

4 Then go to the following web site and download Index 700 of the 2008 Design Standards: The PPM Chapter 4 defines the clear zone concept and goes into detail concerning the clear zone cross section, with a detailed drawing and definition of terms. PPM Chapter 4 also refers back to PPM Chapter 2. PPM Chapter 2 gives a table of minimum recoverable terrain dimensions for various design speeds. For our EXAMPLE 1, with a 50 mph design speed, (assume AADT is greater than 1500) the recoverable terrain requirement is 24 ft. minimum past the edge of the travel lane. Going back to PPM Chapter 4 and reviewing section 4.1.2, we see we must have 24 ft. at a 4:1 slope or flatter, with this width including the shoulder. Read section carefully; it does not specify the exact clear zone but gives the process to determine it. Now go to Index 700 of the Design Standards, and review the flow chart on page This flow chart with associated tables tell us that the clear zone width may vary according to the width of non-recoverable terrain located within the clear zone, depending on the width of recoverable terrain obtained from Table A in Standard 700. This table and method allow the greatest flexibility in working with various roadside conditions and obstructions. Note also that PPM Chapter 4, section 4.3.5, refers to NCHRP Report 537, Recommended Guidelines for Curb and Curb-Barrier Installations, which was discussed in HIGHWAY ENGINEERING I. This report is essential if you are designing a major highway facility using curb or curb-guardrail combinations. ADDITIONAL EXAMPLES - common roadside conditions on highway design projects: For EXAMPLE 2, we have a 45 mph urban roadway with curb. What is the closest point at which a fire hydrant could be placed to the curb? First we turn to Standard 700 and look at the flow chart. We know the design speed, 45 mph. We then look at Table A to determine a recoverable terrain dimension of 24 ft. Then go to Table B to check the restricting conditions, which include curbed facilities. We then check Table C, line 19, Utilities, Page 4

5 and look at the restricted conditions column for fire hydrants, which indicates the hydrant should be located not less than 2 ft. from the face of curb. This distance is from face of curb to the nearest surface of the fire hydrant, not the valve (assume the valve is flush with the ground surface), not the center opening nut. This is the minimum horizontal clearance for the travel lane, not the edge of pavement. If there is an auxiliary lane, the process must be repeated using the auxiliary lane column in Table A. For EXAMPLE 3, we have a 50 mph rural highway with paved shoulders. We have an 8 ft. depth box culvert running transverse to the travel lanes. What is the closest point at which the endwall of this box culvert can be placed to the outer travel lane, assuming no auxiliary lane is present in the vicinity of this box culvert? Again using Standard 700, we locate Table A and find 24 ft. minimum recoverable terrain for this situation, with no restrictions. On Table C, line 11, box culvert with depth greater than 6 ft, the unrestricted column requires us to treat this condition as a drop-off hazard. Line #3 of Table C refers us to Standard 400; it also refers us to Figure 2 of Standard 700. Note the location of the hinge point on Figure 2. If your design allows, the nearest exposed edge of the box culvert headwall must be 24 ft. from the edge of the travel lane. Otherwise, you must provide some type of shielding; refer to Note 2 of Figure 2 for details. Standard 400 is a set of guardrail use details. Should your design preclude the use of 24 ft. clear area to the edge of the box culvert endwall, you would most likely use guardrail as a shielding device, depending on the particular right-of-way circumstances. At that point, Standard 400 becomes applicable. Now let s compare the clear zone requirements from the 2007 Florida Greenbook which you downloaded; assume we have the same conditions as EXAMPLE 3 described above, but the road is a county road. Greenbook minimum standards would apply in this case. Look at page 3-69, Table 3-12, Minimum Width of Clear Zone, and find 50 mph, ADT greater than 1500; this table gives a minimum clear zone width of 18 ft. for a rural (non-curbed) facility. The Greenbook has information on all common design issues and is a comprehensive reference to be used for all roads, streets, and highways in the State of Florida which are not on the state highway or federal-aid systems. Should you be designing a county road, these minimum standards apply. If possible, and right-of-way width allows, it is best to use the Page 5

6 information in the Plans Preparation Manual and the current Design Standards handbooks [formerly Standard Indexes]. Why use these more restrictive guidelines? They provide a safer design, and as traffic volumes on the county road increase, those safety features will result in fewer accidents and injuries. The governing agency may depend on you, as designer, to make this decision. EXAMPLE 4 While we have the reference information available, let s review another common design issue and compare the results. A design is being prepared for a county road, 50 mph design speed, with a rural, paved shoulder cross-section. There is a linear alignment shift of 20 degrees, and you need to determine horizontal curve data and superelevation requirements. Go to the 2007 Florida Greenbook and check Table 3-3, Horizontal Curvature on page For a rural design, this table indicates an 8-15 degree of curvature, with a curve of 695 ft. minimum radius. Then check Table 3-1, on page 3-79 for superelevation rates for this design. Remember, degree of curvature is the number of degrees of central angle of the curve which produces a 100 ft. arc length. EXAMPLE CALCULATION: (use info. on next page) Alignment shift of 20 = central angle of 20 = I I/2 = 10 sine of 10 = R = 716 ft. (see below) C = 2 x 716 x = ft. chord length (see below) circumference = 2 R = 2 x x 716 ft. = ft. arc length (curve length) for 20 central angle = [20/360] x ft. = ft. Compare to the minimum curve length of 750 ft. shown below from PPM Table 2.8.2a Page 6

7 Now let s check the 2008 Plans Preparation Manual, page Table 2.8.2a gives a minimum curve length of 15V (V = Design Speed in mph) for Arterials and Collectors. For our design speed of 50 mph, this would require a minimum curve length of 750 ft. On page 2-43 of this Manual, Table 2.8.3, Maximum Curvature of Horizontal Curve... checking the 50 mph design speed gives a maximum curvature of 8-15 for our situation, same as the 2007 Florida Greenbook. Note however that this PPM Table doesn t specify a minimum radius. The PPM does indicate coordination with the State Roadway Design Office may be required for design of facilities on the State and Federal-Aid systems. The limiting factor is the maximum superelevation rate (e) of 0.10, found in Table This same table gives a radius of 716 ft. for a curve with 8 of curvature. Using the 716 ft. radius and a 20 curve, we get a ft. chord length, and ft. arc length. Check this curve data with PPM page 2-49, Table 2.9.1, Superelevation Rate... Using our minimum curve length of 750 ft. which we determined from Table 2.8.2a in the PPM, we see this 750 ft. length is our limiting factor. The curve radius used must give a curve length of 750 ft. minimum. Now, as a final comparison, let s calculate the curve length determined using the minimum value of 695 ft. radius from the Greenbook: we arrive at a ft. curve length. Comment on EXAMPLES 2, 3, & 4 The Florida Greenbook standards are minimum requirements; it can be seen from the examples above that the Greenbook data may produce an extreme curve for a 50 mph design speed roadway if only the minimum values are used. Greenbook clear zone values also are minimums; looking at the clear zone widths we determined for EXAMPLE 3, above, Standard 700 gave a width of 24 ft., while the Greenbook gave a width of 18 ft. However, Page 7

8 for a horizontal curve with design speed of 50 mph, Table 3-3, Horizontal Curvature in the Greenbook indicates a clearance of 27 ft. is required. Horizontal curve clearance is not specifically addressed in the PPM. The PPM should be used for the roadway design standards where right-of-way is available or obtainable. Should you be entertaining a design for a county or municipal road or street, the recommended procedure would be to hold a discussion with the agency s professional staff to discuss the design criteria to be used, prior to commencing design. Again, agreement in writing for all design issues and standards is mandatory in order to avoid problems during the design production process. E. SIGNING AND SEALING ROADWAY PLANS In Part One of this course series, we briefly mentioned the responsibilities of the Engineer of Record when signing and sealing plan sets. Since we have been discussing the Florida PPM, it is appropriate to review the instructions for signing and sealing plans prepared in Florida as presented by the Florida D.O.T. These instructions are found in PPM Volume II, Chapter 19, Sealing Design Documents. Some states may not have such specific requirements; it is fundamental to check the requirements in the state in which you are practicing. And, if you are licensed in more than one state, you will want to comply with the state in which the facility is being designed, approved, and constructed. Download PPM Chapter 19: Review PPM Chapter 19, sections 19.1, 19.2, and 19.3 concerning public record documents. Rules of the Florida Board of Professional Engineers includes new (2008) specific instructions for signing and sealing documents filed for public record. Now go to the Florida Board of Professional Engineers website and download 61G15 Florida Administrative Code [FAC]: Page 8

9 Review Chapter 23, section , Seal, Signature, and Date Shall Be Affixed. [FAC]. Compare this section with the PPM Chapter 19 sections noted above. Be prepared to answer the following questions: 1. What documents are to be signed & sealed? 2. Who is responsible for signing & sealing documents? 3. What specific information is required to be placed on the document being sealed? 4. When are roadway plans submitted for bidding exempt from signature & seal requirements? F. WAIVING THE DESIGN STANDARDS You have a difficult design condition, and you have researched the situation. You have deterrmined you cannot meet the minimum design standards. What do you do? For highways in Florida, there are two sources for this information: Florida Greenbook Chapter 14, and Florida D.O.T. PPM Chapter 23. You should have the Greenbook available already. Now Download PPM Chapter 23: Checking Greenbook Chapter 14, section B, Design Exceptions, we see that if you use a design standard which has been adopted by ordinance of a local municipality or county, you already have an approved design exception. What if you are designing a highway on the Federal-Aid system and you can t meet the PPM requirements? If you can meet the county-adopted design criteria for the issue at hand, do you have an automatic design exception approval? No, not at all. Check PPM Chapter 23, section 23.3 which you just downloaded. Depending on the extent of FHWA oversight (you are working on a U.S. highway within the Federal-Aid system), you may need full approval from the FHWA Division Administrator and the State Roadway Design Engineer. If your project involves only limited FHWA Page 9

10 involvement, the Design Exception will at least require approval of the District Roadway Design Engineer. See page 23-3 of Chapter 23, in Vol. I of the PPM. The process of obtaining approval is explained further in other sections of Chapter 23. Note carefuly the Approval Letter found on page Now let s return to the Greenbook, Chapter 14; check page 14-6 for the Example Letter. The Greenbook process is similar to the PPM, but differs significantly due to the fact that approval by the D.O.T. or FHWA is not necessarily required. However, all design exception documents must be signed & sealed by the Engineer of Record, or Responsible Engineer. Requesting a design exception is a major issue, and should not be undertaken for minor items which can be eliminated by compliance or by relocating the offending item to provide a compliant design. Requests for convenience or to avoid a right-of-way taking because it may slow down the process (wasn t in your design contract) are not legitimate reasons. G. UTILTIY ADJUSTMENTS & UTILITY ADJUSTMENT SHEETS From the Florida D.O.T. PPM, Volume II, Chapter 20, we have the following text: 20.1 General The purpose of utility adjustment sheets is to provide coordination between the contractor and the affected utility companies. These sheets show the contractor the approximate locations of existing, proposed and relocated utilities, and thus aid the contractor in avoiding possible conflicts or damage to the utilities involved. Projects with minor utility work or impacts may include these features on the roadway plan or plan-profile sheets or appropriate component plan sheets. A major highway project will have its own Utility Adjustment Sheets. On a corridor which already has an existing roadway, there will be extensive utility occupation of the right-ofway. In such cases utility relocation becomes a major task. The designer will be faced with multiple conflicts concerning drainage, clear zone, fire hydrants, power poles, communications, and similar utility occupations. Reasons not to relocate will range from we ve been here longer than the road... or we just can t move to we supported commissioner??? in his re-election campaign. Worst case is a utility in its own easement along an area where the road widening requires right-of-way acquisition. The best answer is Page 10

11 to try to work with the utility as much as possible and avoid a political situation. This type of situation is a test of your negotiating ability. Ultimately, the Engineer of Record will be responsible for completing the design to eliminate clear zone obstructions. This includes relocating utility poles and fire hydrants outside of the clear zone. However, the process isn t complete until the last bore has been finished, and the last pole and conduit have been installed. It is a good idea to use an experienced field engineer to provide on-site construction observation, as many conflicts are resolved during construction. Underground surprises are always present, and you want to avoid conduits installed by boring through drainage pipes, power poles set on top of (and into) water mains, etc. Don t forget the landscape contractor. He will come in last, and may cause the worst damage. The initial utility conference should include a brief discussion of clear zone, who determines this critical dimension, and why it is important. A complete utility list should have been prepared at the commencement of design, including names and phone numbers of all involved agencies. Prior to the initial utility meeting, written letters must be sent to each agency informing them of the project and their involvement in it. The highway owner will most likely have established instructions and procedures for dealing with utilities on the type of project you are involved with. Written communications and certified mail may be part of this process, but it is important to understand you are still dealing with each utility on a personal basis via the designated utility contact person, and you will obtain the best, most efficient results by respecting this personal relationship. At the initial utility conference, the following items may be of use during the discussion: 1. Discuss utility poles and above-ground utilities vs. roadway design standards & immunity from lawsuits. Understanding the clear zone concept is essential. Include the landscape designer. 2. What happens if a utility violates the design elements of a roadway or right-of-way it uses? (Everyone may be sued.) 3. Discuss "utility agreements." Pre-existing agreements may have to be modified. Page 11

12 This may require extensive cooperation with the legal offices of both participants. This process must start at beginning of design. 4. Discuss right-of-way use permits vs. utilities. As a general rule, utilities are required to hold right-of-way use permits for any occupation of public right-of-way. In practice, this may not be the case. On a new project, the proposed occupation should be permitted prior to relocation. 5. If a vehicle hits a utility pole in the right-of-way of a new roadway for which you are the E-O-R., what do you do? Who is responsible? Was the clear zone width provided according to established standards? Most likely, the utility will claim ignorance. Involve your legal office. 6. Use of guardrail - is guardrail a legitimate barrier to protect a pole or fire hydrant which is otherwise unsafely located? Clear zone requirements may need to be reviewed with each agency s designer to establish and emphasize the importance of this issue. 7. Installation of County or City-owned utilities in a public right-of-way? Unfortunately, the most intransigent opposition to relocation or to providing safe clear zone width may come from another government utility agency. This can lead to the battle of the boards, and will place you, as designer, right in the middle of the fight. This is a primary reason to emphasize educating the involved parties of critical design features at the commencement of the design process. H. THE PERMITTING PROCESS This section is included to serve as a brief overview of permitting for highway projects, and is not intended to be complete or comprehensive. Permitting varies by locality and may differ even within a county or local jurisdiction. The process is extremely complicated and Page 12

13 expensive in exchange for the anticipated benefits. Some agencies require a duplication of effort for the same land area or issue. In addition, highway projects which have utility relocations require permitting for each type of utility involved. Environmental Impacts If you have been involved with a highway project on the U.S. Highway system which involves federal aid, you already are aware of the complicated environmental impact assessment process required by the U.S. Environmental Protection Agency. Go to the following web site and review the background information available: Be prepared to answer questions regarding the history and applicablity of NEPA. State and local highway projects which do not use federal aid may require an environmental assessment similar to the U.S. EPA s process, depending on where the project is located. Florida Statutes Chapter address developments of regional impact, and may apply to a project which involves more than one county. Review this statute at the following web site: [ look in Title XXVIII ] Which projects are exempt? What type of development involves a 50% increase to applicable guidelines? Drainage Permitting Drainage permitting will involve one of the regional water management districts, established by Florida Statutes Chapter Review this statute at the web site noted above, also located in Title XXVIII. Each district has its own web site and permitting handbook. Page 13

14 Local drainage permitting may also be required. For example, in Hillsborough County, the county Environmental Protection Commission, originally established by the Florida Legislature, has jurisdiction over surface waters in Hillsborough County, as well as other jurisdictional authority. Go to their web site: and follow the links to the EPC Permitting Guide. This agency provides some duplicate permitting which is also required by the Southwest Florida Water Management District. If your design involves a state highway (no federal aid), you will also have to obtain a drainage permit (right-of-way use permit) from the appropriate Florida D.O.T. District Access Management office. Check the web site below: This web site is a great improvement over the situation of past years when the permitting process was obscure and varied from district to district. Additional permits and coordination may be required for your project depending on the outfall connections and ownership of same. Outfalls into navigable waterways usually involve the U.S. Army Corps of Engineers. This process can become extremely costly if the obstacles are unforseen at the time of design fee preparation. Summary Agency jurisdictional disputes may also arise during the design process. For example, the Florida D.O.T. does not generally recognize local agency permitting requirements. Although coordination would occur, it would be rare for a state agency such as the D.O.T. to obtain a local permit for one of its state highway projects. A project involving a U.S. Highway improvement in the corporate limits of a municipality would be an example. A city right-of- Page 14

15 way use permit would not be applicable to a state D.O.T. project in Florida, because the improvements would be made to state or federal property included in the U.S. Highway system. The same would apply to a State Highway not part of the federal-aid system. This review is not intended to be a complete listing of agencies which may be encountered on a project, but is a brief overview of the issues and complexity of permitting major projects. For the permitting part of the test, be prepared to answer questions similar to the following: 1. Over what projects does the U.S. EPA have jurisdiction? 2. What are the water management districts and how are they involved in highway projects? 3. Is a permit required for a driveway along a state highway? 4. What is a regional impact? 5. Are drainage outfall pipes which discharge into State Highway rights-of-way required to be permitted? END OF PART TWO Page 15