A SunCam online continuing education course HIGHWAY ENGINEERING

Transcription

1 HIGHWAY ENGINEERING TRICKS AND PITFALLS - part one (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 a summary of highway engineering details and design standards which are common to most highway design processes. Examples from Florida practice are used in this course, but it is applicable to any State or region by considering local laws, regulations, and design practices. When you complete this course, you should have learned some common traps and pitfalls which are common to highway design, how to avoid them, and what standards apply to certain circumstances which may not be obvious. 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 do States adopt highway design standards? 2. What is the role of FHWA in the adoption of State design standards? 3. What is sovereign immunity? 4. What is the responsibility of the Professional Engineer who oversees the design Page 1

2 and plans preparation? 5. What are the legal responsibilities and liability of the Engineer of Record? ============================================================== C. DISCLAIMER Neither the author nor SunCam, Inc. is an attorney. If you need legal advice, consult a qualified attorney. ============================================================== D. WHY DO STATES ADOPT HIGHWAY DESIGN STANDARDS? Most 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. This is accomplished for several reasons: 1. To promote a uniformity in design for driving safety and ease of construction. 2. To promote pedestrian and vehicular safety features. 3. To lower construction bid prices by having uniform construction standards, and standard unit bid items, with the ability to compare bid prices. 4. To have uniform minimum standards in place for sovereign immunity against lawsuits. 5. So drivers driving through several states aren t confused by a variety of roadside conditions, signs, and traffic signal systems which send conflicting and/or different visual signals to the driver for similar conditions. 6. To meet FHWA requirements for Federal Funding. ============================================================== E. HIGHWAY DESIGN STANDARDS - PURPOSE AND APPLICATION Page 2

3 Let s review the basic types of highways and roadways which are common to all States: 1. Interstate Highways & Toll Roads; [Toll roads may or may not have a Federal or U.S. Highway designation. For the purpose of this course, it is assumed that the two have similar design criteria.] 2. U.S. (Federal) Highways, excluding limited-access facilities; 3. State-owned and maintained Highways [not U.S. Highway designation]; 4. County-owned and maintained highways and roads [not U.S. Highway designation]; 5. City [municipal] streets and boulevards [not U.S. Highway designation]; 6. Military Facilities. Different design and construction standards apply to each designation listed above. It is important to know which agency owns the right-of-way in which the facility is located; which agency claims ownership of the roadway itself; and which agency maintains the roadway facility. If there is a different agency for each of the three items noted, each agency may have a differing set of design and maintenance criteria, and may want to review the design. The paragraphs which follow review the standards applicable to each type of facility. Interstate Highway Design Standards: The FHWA administers the Interstate Highway Design Standards based on the Federal Aid Highway Act of 1956; these standards were developed by State highway agencies acting through the American Association of State Highway and Transportation Officials [AASHTO], and were adopted by FHWA. These standards are available for purchase from AASHTO in their publication A Policy on Design Standards - Interstate System. The 5th edition of this publication is currently available from the AASHTO web site: Continuing this concept of standardized design criteria, the FHWA lists additional Page 3

4 design requirements for interstate highways on the following website: Title 23 USC 109 provides that design standards for projects on the National Highway System (NHS) must be approved by the Secretary of the U.S. Department of Transportation in cooperation with the State highway departments. The Secretary has delegated this authority to the Federal Highway Administrator. The State highway departments, working through the American Association of State Highway and Transportation Officials, develop design standards through a series of committees and task forces. FHWA contributes to the development of the design standards through membership on these working units, sponsoring and participating in research efforts, and many other initiatives. Following development of the design standards, FHWA uses a formal rulemaking process to adopt those it considers suitable for application on the NHS. The design standards currently adopted by the FHWA can be found at 23 CFR 625. Additional design guides and references can be found in the Federal-Aid Policy Guide, Non-regulatory Supplement NS 23 CFR 625, paragraph 16. The CFR and Nonregulatory Supplement do not include the standards themselves, but rather a list of publications which contain the standards. Probably the most frequently used document in 23 CFR 625 is A Policy on Geometric Design of Highways and Streets. This page document, sometimes called the Green Book because of the color of its cover, is published by AASHTO and can be found in many public libraries. The Green Book can also be purchased from the AASHTO web site noted above. Why adopt uniform Interstate Highway design standards? For all of the six reasons listed in D above; should different States have differing Interstate Highway design criteria, a confusing and potentially unsafe group of features would be encountered while driving from State to State along an interstate highway. It would be similar to driving from Germany to Denmark and encountering different traffic signals, signs, and Page 4

5 roadside features. Having a set of design standards for interstate highways also provides sovereign immunity against lawsuits if the design criteria are followed. Sovereign immunity prevents lawsuits against a government or governmental agency unless it agrees to be sued. If a State agency adopts design criteria which have been prepared by experts in that field, and enforces those criteria, it has sovereign immunity from lawsuits related to the facility if the facility was designed using the adopted criteria. Usually this immunity is encoded in the statutes for the State under consideration. Sovereign immunity goes back to the Middle Ages, and is a concept that the King can t be sued, hence the use of the word sovereign. Sovereign immunity may also apply to designs for State highways and other roads and streets in a County or State. If you are designing roads, you need to be aware of any immunity statutes which apply to the governmental jurisdiction in which the design is located. U.S. (Federal) Highway Design Standards: U.S. Highways are also governed by FHWA Standards, because the right-of-way is either Federally-owned with State jurisdiction by assignment, or by Federal funding, or is owned outright by a Federal Agency. These U.S. routes all fall within the National Highway System, (NHS), and are under FHWA jurisdiction by Federal Statute, 23 USC 109. It is important to know this information when you are working on the design of a U.S. Highway. More than likely, the agency with whom you are under contract will be your best source of knowledge for this information. The FHWA has posted links to State Roadway Design Manuals on its web site: The AASHTO Green Book [A Policy on Geometric Design of Highways and Streets, 5th Edition] is considered to be the source for highway design in all jurisdictions, and is cited by FHWA on their web site for design criteria, as noted previously. Most Page 5

6 probably, if you are preparing a design which involves a U.S. Highway, the State Department of Transportation in the State in which you are working will have been assigned to oversee all designs prepared for U.S. Highways in that State. If you are not under the immediate authority of the respective State Department of Transportation, you will likely need to permit your design through that same State Department of Transportation, which will represent the Federal Government with respect to designs for a U.S. Highway. State Highway Standards: Title 23 USC 109 provides that projects (other than highway projects on the NHS) shall be designed, constructed, operated, and maintained in accordance with State laws, regulations, directives, safety standards, design standards, and construction standards. Again we refer to State Statutes and Administrative Code specific to the State in which you are working in order to determine the exact design criteria and standards which apply to your project. Most States have adopted statutes and regulatory codes pertaining to State Departments of Transportation. These statutes and codes are commonly available on the internet and should be used to determine the applicable requirements for a particular project. For example, in Florida, the State Department of Transportation is specifically chartered as a decentralized agency under the Executive Branch (Governor) of the State Government (Fla. Stat ). What does this mean? The Florida D.O.T. has a degree of autonomy and is not subject to the whims of individual legislators, because it does not fall under the Legislative Branch of State Government for direct management on a year-to-year basis. This same statute gives authority to the Secretary of Transportation for Design, Construction, Maintenance, and Materials, among other things, related to transportation in Florida. Where do you find the State Design Standards for a particular project on a State Highway? First, look on that State s D.O.T. web site for a link to a downloadable design handbook or set of standard design drawings. The FHWA web site noted above is a good place to start. The Florida D.O.T. has a very good web site listing all their Page 6

7 publications, including free downloads of their design standards and other publications: In particular we are referring to the following Florida D.O.T publications: Design Standards, Drainage Handbooks, Drainage Manual, Plans Preparation Manual, Utility Accommodations Manual, and Roadway and Traffic Design Standards, all available as free downloads at the website noted above. They are listed here as reference sources, not as required study material for this course. Remember that AASHTO s Green Book has been universally adopted in most States as the geometric reference for highway design. Depending on your project s particular circumstances, additional standards and local criteria may apply, such as for walkways, pedestrian features, landscaping, drainage, etc. It is particularly important to obtain, prior to commencement of design, agreement from all the participating agencies, especially on State Highway projects, on the specific design criteria, standards, and standard drawings to be used for a particular project. This avoids the critical problems of redesign requests and arguments over which criteria apply, especially after the 50% completion stage. The Florida D.O.T. has a variety of manuals and standards for use in design of new roadway facilities. This is why it is of fundamental importance to come to agreement on the design criteria to be used on a particular project. For example, the Florida DESIGN STANDARDS may apply to a new roadway segment under design, which is funded solely by the State of Florida. Florida also has its own Green Book, which is Page 7

8 the statutory minimum design criteria for roads, highways, and streets in the State of Florida, but this Green Book does not apply to every highway project in Florida. Download this free current Green Book at: Check the Table of Contents and find 3 specific design situations to which this manual and design criteria apply. As a highway designer/engineer, you are ultimately professionally responsible for choosing and using the appropriate design criteria for your project if you sign and seal the plans. County and City Roads, Streets, & Highways: AASHTO s Green Book is the fundamental reference in this category. Since there are many different criteria adopted by counties and local municipalities, two issues are worth repeating: 1. Obtain agreement of the participating agencies on the specific design criteria to be used for design of the facility in question, prior to commencing design. 2. The design professional is ultimately responsible for choosing and using the appropriate design criteria for a particular facility. Professional liability cannot be transferred simply by writing a letter or receiving a letter from a non-licensed government employee. As mentioned above, Florida has specific design standards for new highway design in State-owned rights-of-way. Florida also has its own Green Book for minimum standards for all roads, streets, and highways in Florida. All the criteria listed here may apply to a project within the city limits of a municipality in Florida. It is particularly important not to allow a non-professional employee of a government agency to dictate the specific design criteria to be used for a road, street, or highway project. As a Page 8

9 professional, you are responsible for the design criteria used for your design, and if there is a safety problem later, you will ultimately be held responsible. Should a professional engineer employed by a local government indicate that an inappropriate design standard be used for a project which you are designing, you must either refuse to use it, or obtain his written, signed, sealed letter assuming full responsibility for use of such criteria. If this design criteria is obviously incorrect, you will most likely be held responsible for its use as designer, regardless of any documents obtained. Military Facilities (Roads, Streets, Soil Mechanics): The Department of Defense has a number of excellent technical manuals applicable to highways. Some are dated and may have been superseded by recent FHWA or other publications, but contain good basic information useful for highway and other facility design. All are available as free downloads from: You can also download NAVFAC Publications from: From the Whole Building Design Guide website, download the following: Unified Facilities Criteria: UFC FA Pavement Design for Roads, Streets, Walks, and Open Storage Areas as a pdf file, ( ). This document is located at: This manual goes into great detail regarding the design of pavements for military facilities; it also provides a lot of information concerning concrete pavement. It should be noted that this information is 20+ years old and may not be up to date. This manual is referenced in this course to illustrate the type of free documents available from the Department of Defense and the type of information presented. If you are preparing a Page 9

10 design for a military facility, the specific contracting officer may instruct you or your firm to use a more current set of design criteria, especially if the design concerns a large facility or heavy vehicle traffic. This criteria, as noted previously, MUST be agreed upon in writing in advance of the start of the design process. Review this handbook in detail and be prepared to answer the following types of questions: a. Who or what agency prepared this document? b. Under what category is it available? c. Can anyone use this manual? d. What types of preliminary investigations are made prior to commencing a highway design? e. Traffic evaluation and analysis are performed for what reason? f. Is subgrade a consideration in pavement design? g. What is CBR? Why is it important? h. How is flexible pavement thickness determined in this manual? i. When is frost action a consideration? See Chapter 18. j. How does this manual address the design of rigid pavement? k. Does the manual address the repair of flexible pavement with a rigid overlay? l. Why are geotextiles used in the design and construction of pavement? m. What is an RCC pavement? n. What does Figure 18-2 illustrate, and why is this important for design? o. What is mentioned regarding use of state highway design criteria? ============================================================== F. INTEGRATED HIGHWAY DESIGN - CONSIDERATIONS A final design of a highway should integrate all the design features considered by the scope of services of the contracting agency, as well as providing full safety elements for pedestrians and vehicles. As a professional, it is incumbent upon you to offer the design services you know will be required to provide a complete and safe design. Most Page 10

11 agencies have a predetermined budget and may try to cut services in order to force budget compliance, but this does not mean they always know what they are doing. This is a critical issue. You cannot design a highway without proper drainage; neither can you omit pedestrian or vehicular safety features just because the contracting agency does not want to pay for these services. Underground Utilities Underground utilities are always a major consideration on a large highway design project, especially in urban areas where the existing right-of-way is being reused for an expanded facility. This underground design work will be a major expense and cannot be ignored during the design process. If there are underground utility conflicts (there always are), it is much cheaper to deal with them during design, than wait for the contractor to dig them up during the construction phase. Some extra engineering time is always less expensive than paying a contractor for a couple of idle work crews. These conflicts can sometimes be characterized as unforeseen conditions, which may lead to a design fee supplement if the agency is open-minded about the project. If not, it is always better to provide the services anyway in order to avoid a potentially expensive construction claim later. This issue is a recurring problem with highway projects. Centerline of Construction Another issue which seems to be often overlooked is the floating centerline of construction. For some reason, designers appear to make scavenger hunts out of construction plans for highways. If the construction centerline (it should be the actual centerline, not just a relabeled baseline of survey) is not dimensioned to the actual rightof-way on either side of the road alignment, the contractor is presented with an unknown layout puzzle wherein he has to guess where the construction is to be placed within the right-of-way. The centerline of construction should be dimensioned to the right-of-way on each page of the plans in an unequivocal way. There should be no confusion. The right-of-way should be tied to existing reference points on the ground at each end of the project so the layout crew does not have to do basic land and monument research prior Page 11

12 to laying out the construction project. This is the initial engineering work which a design firm is retained to perform. It should not be left to the contractor to finish the design; as Engineer of Record, you are going to sign and seal those plans. Signature and Seal of Plans Don t forget that a chief engineer in overall charge of a highway design has responsibilities which differ from state to state. Florida has specific requirements regarding the signing and sealing of different aspects of a highway design. State licensing law must be checked prior to applying your signature and seal to any sheet of a set of highway plans. For Florida, instructions for signing and sealing plan sets are found in Florida Administrative Code Chapter 61G , titled: Seal, Signature and Date Shall Be Affixed. A current copy of 61G15 FAC can be found at: ============================================================== G. POST-DESIGN SERVICES Should you be involved in the design of a major highway facility, more likely than not your firm will be asked to provide post-design services of some type, whether it is actual field inspection, contract management, or just design interpretation and/or shop drawing review. This is a critical phase of the process because it is where all the inconsistencies and errors come to light and must be dealt with by someone. Experienced personnel must be available to assist with this function. In order to establish the scope of these post-design services, the Department of Defense has produced a document which includes guidelines for the services being contemplated. This manual is useful for almost any type of governmental post-design services contract. Contracting with a Government Agency to Provide Post-Design Services Page 12

13 Go to the NAVFAC site described in the preceding section above: From this NAVFAC site, click on the Complete List of Documents at left side of the page, and then download: Guidelines for Architect/Engineer Construction Surveillance & Inspection Services If the above link is not working then this document may be viewed on SunCam s web site at document number NAVFAC P-1015, May This is an excellent general review of contracting responsibilities for field inspection services for government projects. Although it is a 1986 document intended for US Navy construction contracts, it applies almost universally to government inspection contracting. Review Chapter 4, Administration... You should be prepared to answer who has responsibility for inspection of construction details, what document assigns those responsibilities, and who approves monthly construction payments/invoices for the project. Also determine the construction contract payment types and what or who assigns those payment types. ============================================================== H. ROADSIDE DESIGN ELEMENTS AND SAFETY FEATURES When a highway or major arterial roadway is being designed, the primary focus is upon lane configuration, right-of-way, and drainage. Roadside safety is often given a back seat to these other considerations because it just has to fit in with everything else. You can be assured an astute attorney will make it a primary consideration in an injury lawsuit if obstacles have been introduced into the clear recovery area which have damaged a vehicle in a crash. What do we mean when we discuss roadside safety? Right-of-way width, slope of shoulders, slope of roadside ditches, utility poles, Page 13

14 mailboxes, sign supports, and guardrail placement are all examples of issues to be concerned with when working on roadside safety. Clear recovery area is dependent on the type of facility under consideration; higher vehicle speeds lead to wider clear recovery areas. The appropriate width must be determined at the start of design. This usually leads to a right-of-way width conflict, depending on how carefully the preliminary alignment study was prepared. If property acquisition was not originally contemplated, the contracting agency may need to become involved with an inadequate right-of-way width situation as soon as the problem is discovered, as this will involve additional property taking, courts, attorneys, and the landowners themselves. Roadside Obstacles Roadside obstacles include utility poles, sign supports, fire hydrants, guardrail, concrete barrier wall, drainage inlets and headwalls, mail boxes, and similar items, which all present a hazard to vehicles which leave their respective through-lanes and need clear space to recover trajectory. Each obstacle must be addressed in a way which conforms to current design criteria and can be defended in court in case of a lawsuit. Do your designs allow fire hydrants within the clear recovery area of a roadway? If so, you may want to check your liability insurance. A fire hydrant is a significant obstacle to a vehicle, and usually you will get no sympathy from the utility owner. It may be possible to place a fire hydrant in its own easement outside of the clear recovery area. When considering roadside design, pedestrian and vehicle safety are the primary considerations. Utility companies which have occupied rights-of-way for many years are not interested in roadside safety any more than they are interested in preserving your professional engineer s license. There may be difficult negotiations with utility company representatives over obstacles in the right-of-way; the bottom line is that your license is at stake. Another common problem is the use of landscape planters, brick or concrete fountains, and signs at subdivision entrances which are placed within the clear recovery area of a highway. Guard booths for restricted-access communities have also been placed within Page 14

15 clear recovery areas. Substantial trees may be required to be planted by ordinance along new highways in clear recovery areas. Even though this is a political situation, you may have to refuse. Roadway construction plans should never show any construction of this type on the design. Most landscape architects are not aware of the clear recovery area concept and you may have to educate them as part of your design process. Finally, keep the landscaping on its own drawing set, separate from anything you sign and seal. Guardrail Guardrail is a hazard by itself; it can be useful under certain circumstances, but it should not be used as a cure-all for unmovable obstacles. Some designers have the mistaken idea that guardrail is used to protect an unmovable obstacle from errant vehicles. Again, an attorney will correct this mistaken impression at some point. Guardrail should be considered as a launching ramp in many situations. The Transportation Research Board (TRB) has several publications on the use of guardrail at their bookstore web site: If you encounter a situation which appears to require guardrail, there can be no substitute for the TRB research information and state highway agency standard design information. Each location requiring the use of guardrail should be examined for alternatives prior to incorporating guardrail into the design. See the section below on use of concrete curb for the reference to NCHRP Publication # 537, which includes guardrail installation. Break-Away Signs FHWA has standards for sign mounts along interstate highways which launch the sign and post upward and out of the way of a striking vehicle. This design is to prevent windshield impact and driver injury as much as possible. The bolts on these break-away sign mounts have been chosen to fail in shear when hit by a vehicle. Substitution of the original bolt with stronger bolts will cause the break-away mount to malfunction. If you Page 15

16 or your firm is retained to provide construction monitoring services, it is very important that your field personnel carefully observe and check the bolt installation and applied tightening torque so that it is all within the design requirements and specifications. Use of Concrete Curb as a Roadside Safety Barrier Highway design firms often encounter roadway improvement projects wherein an existing highway will be partially redesigned to include new traffic signals, pedestrian features, and/or drainage improvements without changing the basic lane configuration. Inserting traffic signal poles, sidewalks, handicap ramps, fire hydrants, and new utility poles into an existing roadway creates a design nightmare. Usually the right-of-way width will not allow the new features to be installed while preserving roadside safety. Some designers have used short, asymmetric sections of 6 concrete curb to artificially reduce the apparent clear recovery area from perhaps 24 ft. to 4 ft. in the congested area. However, this unexpected short curb section becomes nothing less than a launching ramp for a vehicle which is traveling at the speed limit and moves just a few inches off the lane line. In order to properly reduce the established clear recovery area by use of curb, the roadway must transition from rural to urban section with clear advance warning and guidance to the drivers of the vehicles. A short section of curb does nothing but confuse the driver and present a hazard to all users of the facility. This situation is a dilemma and must be discussed openly with the owning agency prior to finalizing the design. There is no easy answer to this type of problem. Usually additional right-of-way is required. The TRB has a useful publication listed as NCHRP Report # 537, Recommended Guidelines for Curb and Curb-Barrier Installations, which may be of help should you encounter the situation described above. This is a free downloadable publication at: Page 16

17 Download this publication and review the Forward carefully. Be prepared to answer the following questions: a. Which agency comments on the use of curbs on high-speed roadways? b. What role do curbs play in crashes on high-speed highways? c. What effect does restricted right-of-way have on the use of curbs? d. What is NCHRP Project 22-17? e. How were vehicle impacts with curbs investigated? f. What were the recommendations of the study and Report? ============================================================== END OF PART ONE Page 17