TRANSMITTAL LETTER. Guidelines for the Design of Local Roads and Streets December 2009 Edition

Transcription

1 OS-299 (7-08) TRANSMITTAL LETTER PUBLICATION: December 2009 Edition DATE: December 21, 2009 SUBJECT: Guidelines for the Design of Local Roads and Streets December 2009 Edition INFORMATION AND SPECIAL INSTRUCTIONS:, "Guidelines for the Design of Local Roads and Streets", is to be re-issued with this letter. An itemized listing has not been provided for all of the changes. A summary of the major changes is listed below. GENERAL CHANGES -Updated to be consistent with the Department's Publication 13M, Design Manual, Part 2, "Highway Design" (August 2009 Edition) and to reflect implementation of Smart Transportation and Design Flexibility guidance. -Updated publication dates, references, and numerous design values for consistency with AASHTO s "A Policy on Geometric Design of Highways and Streets" ( Green Book) and "Roadside Design Guide" (2006). -Changed reference from "the AASHTO Green Book" to "the Green Book" for clarity. -Updated references as required to section numbers and page numbers. -Updated references as required to Exhibits found in the Green Book. -Added references to specific sections in the Green Book to assist the reader in locating relevant design guidelines. -Updated references to the Department's publications. -Updated Table of Contents. PREFACE -Inserted second sentence. CHAPTER 1 GENERAL DESIGN GUIDELINES Section 1.0 (Introduction): -Second Paragraph: Inserted first sentence for consistency with the Department's Smart Transportation principles. -Fourth Paragraph: Inserted second and third sentences describing the roadway environment for pedestrians, including access, safety, and needs. -Fifth and Sixth Paragraphs: Inserted paragraphs describing the American with Disabilities Act (ADA) and stating how its accessibility provisions apply to the transportation project development process. -Eleventh Paragraph: Inserted new paragraph discussing Publication 282, Highway Occupancy Permit (HOP) Guidelines and access for local roads and driveways to Department-owned roadways. Section 1.1 (Land Use Context and Roadway Typologies): -Replaced previous section titled, "Urban and Rural Area Definitions". The Department's Smart Transportation principles are based on determining the design criteria and project scope for a roadway when its roadway typology, land use context, and functional classification have been identified.

2 -Added Table 1.1 (Roadway Typologies) and Figure 1.1 (Illustrated Roadway Typologies). CHAPTER 2 LOCAL RURAL ROAD SYSTEM Section 2.0 (Introduction): -First Paragraph: Revised paragraph for consistency with write-ups for roadway typologies in Chapter 1, Section 1.1. Added sentence referring to Table 1.1 and Figure Second Paragraph, Third Sentence: Added reference to newly labeled Figure 2.1 (Functional Classification System Service Characteristics). -Third Paragraph, First and Third Sentences: Changed "Local Access Roads" to "Local Roads"; changed "Local Access" to "Local Roads". -Third Paragraph, Second Sentence: Added sentence noting that municipalities may own roads that fall under any or all of the general functional classifications (Arterials, Collectors, or Local Roads). -Fourth Paragraph: Revised values for average trip lengths of arterials for consistency with Table Fifth Paragraph, First Sentence: Changed "local access roads" to "local roads". -Sixth Paragraph, First Sentence: Changed "Local Access" to "Local Road". -Figure 2.1 (Functional Classification System Service Characteristics): Added figure title. Section 2.1.F (Pavement Design): -Deleted Tables 2.1 and 2.2 (Design Guidelines for the Maximum and Minimum Depths of Pavement Courses). -Third and Sixth Paragraphs: Deleted references to Tables 2.1 and 2.2; replaced with references to the Department's Publication 242, "Pavement Policy Manual". -Fifth Paragraph: Revised paragraph, fourth bullet, and sixth bullet about overlays having a thickness less than 40 mm (1.5 in) for consistency with the Department's Publication 242, "Pavement Policy Manual". Section 2.1.G (Guide Rail): -Second Paragraph, Second Sentence: Relabeled reference from Table 2.3 to Table Table 2.1: Relabeled from Table 2.3. Section 2.2.A (Design Traffic Volumes): -Revised section for consistency with similar write-up found in the Department's Publication 13M, Design Manual, Part 2, "Highway Design", Section 2.19.C.4 (Projection of Future Traffic Demands). Section 2.2.B (Design Speed): -Revised section for consistency with Smart Transportation principles and with discussion found in the Department's Publication 13M, Design Manual, Part 2, "Highway Design", Section 2.9 (Design Speed). Section 2.2.B.1 (Projects with New or Modified Speed Posting): -First Paragraph: Added sentence at the end of the paragraph stating the design speed shall not be less than the post-construction regulatory speed limit. Section 2.2.C (Number of Lanes): -First Paragraph: Deleted third sentence indicating the traffic volumes (up to 450 vehicles per hour in one direction) that two travel lanes can handle. -Second Paragraph, First Three Sentences: Revised text for consistency with Smart Transportation principles and with discussion found in the Department's Publication 13M, Design Manual, Part 2, "Highway Design", Section 2.18.M (Highway Capacity Analysis). Section 2.2.D (Right-of-Way): -Fifth Sentence: Inserted publication number for the Department's "Right-of-Way Manual".

3 Section 2.2.E (Structures): -First and Second Paragraphs: Incorporated revisions of design specifications for structures (Refer to Strike-Off-Letter ). -First Paragraph, Second Sentence: Modified discussion about selecting bridge widths for consistency with the Department's Publication 13M, Design Manual, Part 2, "Highway Design". -Third Paragraph, First and Second Sentences: Adjusted discussion for minimum vertical clearance to indicate an allowance of "up to" 0.15 m (6 in), for consistency with the Department's Publication 13M, Design Manual, Part 2, "Highway Design", Section Third Paragraph, Third Sentence: Inserted chapter and section where additional vertical clearance requirements are found in the Department's Publication 13M, Design Manual, Part 2, "Highway Design". -Fourth Paragraph: Deleted "in the applicable Design Criteria Charts" between "indicated" and "in". -Fifth Paragraph: Deleted reference to Section 1.0 in the Department's Publication 13M, Design Manual, Part 2, "Highway Design". Section 2.2.F (Intersection Design): -First Paragraph, Seventh Sentence: Changed "presented" to "identified". -Third Paragraph: Replaced second sentence on curb radii with four sentences for consistency with Smart Transportation principles. The values for curb radii account for roadway classification (e.g., collector and arterial roadways). -Seventh Paragraph: Added wording for consideration of auxiliary lanes and parking lanes. Section 2.2.G (Traffic Control Devices): -First Paragraph, Fifth Sentence: Inserted reference to the Department's Publication 46, "Traffic Engineering Manual". -Second Paragraph, Third Sentence: Deleted "TC-7800 Series" at the end of the title for Publication 148, "Traffic Standards - Signals". -Third Paragraph: Inserted new paragraph describing flashing beacons (flashing warning devices). -Seventh Paragraph, Second Sentence: Changed object marker from "W16-1" to "OM-3L or OM- 3R". -Seventh Paragraph, Third Sentence: Changed "by floodlighting" to "with permanent lighting. Refer to Section 2.3.E for additional guidance." Section 2.2.I (Erosion Control): -Fourth Sentence: Inserted reference to the Department's Publication 584, "PennDOT Drainage Manual". Section 2.3.B (Driveways): -Second and Fifth Paragraphs: Added reference to the Department's Publication 13M, Design Manual, Part 2, "Highway Design", Chapter 7. Section 2.3.C (Mailboxes): -Deleted previous first four paragraphs. Section 2.3.D (Railroad-Highway Grade Crossings): -Added second paragraph with reference to the Department's Publication 371, Grade Crossing Manual. Section 2.3.F (Pedestrian Facilities): -Added this new subsection with reference to Chapter 3, Section 3.4.E. Section 2.4 (Design Criteria): -Deleted the word "CHARTS" from section heading. -Added nine paragraphs pertaining to how the design criteria was developed. -Updated and moved the design criteria information to Appendix A, "Design Criteria and Typical Roadway Cross Sections".

4 Section 2.5 (Typical Roadway Cross Sections): -First Paragraph: Clarified that the Typical Roadway Cross Section details shall be used in the design of typical sections for new highway construction projects on new alignment. -Added three paragraphs describing how the design values for typical roadway cross sectional elements are intended to be used. -Updated and moved details for typical roadway cross sections to Appendix A, "Design Criteria and Typical Roadway Cross Sections". CHAPTER 3 LOCAL URBAN ROAD SYSTEM Section 3.0 (Introduction): -First Paragraph, First Sentence: Revised discussion to indicate the concepts utilized for the local urban road system (land use context, functional classification, and roadway typologies). -First Paragraph, Fourth Sentence: Revised reference to newly labeled Figure 3.1 (Functional Classification System Service Characteristics). -Second Paragraph, First Sentence: Changed "Local Access Roads" to "Local Roads". -Second Paragraph: Added second sentence stating that municipalities may own roads that fall under any or all of three general functional classifications (Arterials, Collectors, and Local Roads). -Fourth Paragraph, First Sentence: Changed "local access highways" to "local roads". -Fifth Paragraph, First Sentence: Changed "Local Access" to "Local Roads". Section 3.1 (Roadway Typologies): -Replaced the previous section, "Urban Area Sub-Section Classifications". Section 3.2.A (Alignment): -First Paragraph: Added fourth sentence indicating that vertical curvature also impacts operating speeds. -Second Paragraph: Revised discussion about curve radii. Section 3.2.C (Superelevation): -Deleted fifth, sixth and seventh sentences. -Fifth Sentence: Added reference to the minimum and maximum cross slopes found in Chapter 2, Section 2.4. Section 3.2.G (Medians): -Deleted first ten paragraphs; replaced with ten new paragraphs discussing traversable and nontraversable medians for consistency with Smart Transportation principles. Section 3.3.A (Design Traffic Volumes): -First and Second Paragraphs: Revised text with references to land areas. -Third Paragraph: Added four sentences for consistency with the Department's Design Manual, Part 2, "Highway Design", Chapter 2, Section 2.19.C.4 (Projection of Future Traffic Demands). Section 3.3.B (Design Speed): -Replaced previous two paragraphs with text referencing Chapter 2, Section 2.2.B. Section 3.3.C (Number of Lanes): -First Paragraph: Inserted new paragraph similar to the paragraph inserted into Section 2.2.C. -Second Paragraph, Second Sentence: Replaced "should carry 300 to 400 vehicles per hour at satisfactory" with "should provide". Section 3.3.E (Structures): -Moved text from first paragraph to new second paragraph. Section 3.3.F (Intersection Design): -Deleted fourth paragraph, last sentence; sixth paragraph; and seventh paragraph, first sentence. -Fifth Paragraph: Inserted text similar to what was added in Section 2.2.F. -Sixth Paragraph: Inserted text to mention a roundabout as a feasible alternative.

5 Section 3.3.J (Curbs): -Second Paragraph, Fourth Sentence: Noted how the Chapter 4 provides guidance to the designer by illustrating commonly used configurations for vertical curbs and sloping curbs. -Third Paragraph: Inserted paragraph with consideration of using curbs for low-speed design (upper limit of 70 km/h (45 mph)) and using curbs with caution for design speeds greater than or equal to 80 km/h (50 mph). -Fourth Paragraph, Third Sentence: Inserted sentence referencing the Department's Publication 72M, "Roadway Construction Standards", Drawing RC-67M. For curb ramps and sidewalks, construction details may be modified to adapt dimensions to existing curb heights where the curb is less than the standard 200 mm (8 in) height. -Fifth Paragraph: Moved last three sentences into their own (fifth) paragraph. Added text in the last sentence identifying reference to RC-64M (see Sheet 1 of 1, Note 6), where a municipality may permit 150 mm (6 in) high curbs adjacent to parking lanes. -Seventh Paragraph, Sixth Sentence: Added reference to the Department's Publication 13M, Design Manual, Part 2, "Highway Design", Chapters 6, 7 and 12. Section 3.4.E (Pedestrian Facilities): -First Paragraph, Third Sentence: Deleted "curb cuts (provides vehicle access over a curbed section of roadway)". -Second Paragraph, Second Sentence: Changed "CBD's" to "business districts". -Third Paragraph: Revised for consistency with the Department's Publication 13M, Design Manual, Part 2, "Highway Design", Chapter 6 (Pedestrian Facilities), Section Third Paragraph, Third Bullet: Deleted "Curb cuts" before the bullet for "Refuge islands". -Fourth Paragraph, First Sentence: Inserted reference to the Department's Publication 46, "Traffic Engineering Manual". Section 3.4.F (Cul-De-Sacs and Turnarounds): -First Paragraph: Deleted third sentence. -Fourth Paragraph: Inserted paragraph with requirements for dead-end roads and cul-de-sacs described in the Department's Publication 9, "Liquid Fuels Handbook". Section 3.4.I (Parking Lanes): -Third Paragraph, Seventh Sentence: Changed "Pennsylvania Code, Title 67, Chapter 201" to "Department's Publication 212, 'Official Traffic Control Devices'". -Fourth Paragraph: Deleted previous fourth and fifth paragraphs, which discussed widths of parking lanes, and replaced them with one paragraph referring to Chapter 2, Section 2.4 and to Appendix A. Section 3.4.J (Mass Transit Facilities): -Fifth Sentence: Added reference to the Department's Publication 13M, Design Manual, Part 2, "Highway Design", Chapter 19. Section 3.4.M (Traffic Calming): -Inserted new section with three paragraphs, including reference to Publication 383, "Pennsylvania's Traffic Calming Handbook". Section 3.5 (Design Criteria): -Deleted the word "CHARTS" from section heading. -Deleted the word "charts" between "criteria" and "presented". APPENDIX A DESIGN CRITERIA AND TYPICAL ROADWAY CROSS SECTIONS Section A.0 (Design Criteria): -Moved information from Design Criteria (Section 2.4). -Added Table 1.1 from the Department's Publication 13M, Design Manual, Part 2, "Highway Design". -Second Paragraph, First Sentence: Placed a footnote on each page to identify the corresponding page where the information is found in the Department's Publication 13M, Design Manual, Part 2, "Highway Design".

6 -Third Paragraph: Added paragraph to describe how broad range of measures that can be used alone or-in combination with other that are highly cost effective when used in place of full construction. Section A.1 (Typical Roadway Cross Sections): -Moved information from Typical Roadway Cross Sections (Section 2.5). APPENDIX B REFERENCES -Moved references from Appendix A to Appendix B. -Revised and reorganized list of PennDOT publications by publication number. -Added note to provide electronic link to the Department's Publication 12, PennDOT Sales Store Price List. -Completed minor revisions to dates and titles for publications issued by AASHTO and FHWA. Any comments or questions regarding the new edition should be directed to the Standards and Criteria Section, Highway Quality Assurance Division, Bureau of Design. CANCEL AND DESTROY THE FOLLOWING: (December 2002 Edition and all associated changes) SOL (Feb. 3, 2009) ADDITIONAL COPIES ARE AVAILABLE FROM: IZI,PennDOT SALES STORE (717) phone (717) fax ra-penndotsalesstore.state.pa.us ~ PennDOT website- Click on Forms, Publications & Maps ~ DGS warehouse (PennDOT employees ONLY) APPROVED FOR ISSUANCE BY: ALLEI\I D. BIEHLER BY: ~~ Brian G. Thompson, P.E. Director of' Bureau' of Design, Highw~y Administration

7 Guidelines for the Design of Local Roads and Streets - December 2009 Edition BUREAU OF DESIGN PUB 70M (12-09)

8 Preface PREFACE, Guidelines for the Design of Local Roads and Streets, provides procedures and guidelines for the application and design of local roads and streets. This publication is for guidance and information purposes only; it is not regulatory. When the Average Daily Traffic (ADT) is less than or equal to 400 vehicles per day, additional guidance is provided in Guidelines for Geometric Design of Very Low-Volume Local Roads (ADT 400), published by the American Association of State Highway and Transportation Officials (AASHTO). i

9 Preface BLANK PAGE ii

10 Table of Contents PUBLICATION 70M GUIDELINES FOR THE DESIGN OF LOCAL ROADS AND STREETS CHAPTER SUBJECT PAGE PREFACE... i CHAPTER 1 GENERAL DESIGN GUIDELINES 1.0 INTRODUCTION LAND USE CONTEXT AND ROADWAY TYPOLOGIES A. Land Use Context B. Roadway Typologies CHAPTER 2 LOCAL RURAL ROAD SYSTEM 2.0 INTRODUCTION DESIGN AND CROSS SECTION ELEMENTS A. Terrain B. Alignment C. Sight Distance D. Superelevation E. Grades and Radii F. Pavement Design G. Guide Rail DESIGN CONTROLS A. Design Traffic Volumes B. Design Speed C. Number of Lanes D. Right-of-Way E. Structures F. Intersection Design G. Traffic Control Devices H. Utilities I. Erosion Control J. Curbs GENERAL DESIGN CONSIDERATIONS A. Bikeway Facilities B. Driveways C. Mailboxes D. Railroad-Highway Grade Crossings E. Lighting F. Pedestrian Facilities DESIGN CRITERIA TYPICAL ROADWAY CROSS SECTIONS CHAPTER 3 LOCAL URBAN ROAD SYSTEM 3.0 INTRODUCTION ROADWAY TYPOLOGIES TOC - 1

11 Table of Contents 3.2 DESIGN AND CROSS SECTION ELEMENTS A. Alignment B. Sight Distance C. Superelevation D. Grades E. Pavement Design F. Guide Rail G. Medians DESIGN CONTROLS A. Design Traffic Volumes B. Design Speed C. Number of Lanes D. Right-of-Way E. Structures F. Intersection Design G. Traffic Control Devices H. Utilities I. Erosion Control J. Curbs GENERAL DESIGN CONSIDERATIONS A. Bikeway Facilities B. Driveways C. Mailboxes D. Railroad-Highway Grade Crossings E. Pedestrian Facilities F. Cul-De-Sacs and Turnarounds G. Alleys H. Outer Separations and Border Areas I. Parking Lanes J. Mass Transit Facilities K. Lighting L. Landscape Development M. Traffic Calming DESIGN CRITERIA TYPICAL ROADWAY CROSS SECTIONS APPENDIX A DESIGN CRITERIA AND TYPICAL ROADWAY CROSS SECTIONS... A - 1 APPENDIX B REFERENCES... B - 1 TOC - 2

12 Table of Contents LIST OF FIGURES FIGURE SUBJECT PAGE 1.1 Illustrated Roadway Typologies (Continued) Illustrated Roadway Typologies Functional Classification System Service Characteristics Functional Classification System Service Characteristics TOC - 3

13 Table of Contents LIST OF TABLES TABLE SUBJECT PAGE 1.1 Roadway Typologies Barrier Requirements for Embankment Heights TOC - 4

14 Chapter 1 - General Design Guidelines CHAPTER 1 GENERAL DESIGN GUIDELINES 1.0 INTRODUCTION This Publication has been developed to provide current, uniform procedures and guidelines for the application and design of safe, convenient, efficient and attractive local roads and streets which constitute a high proportion of the roadway length in the Commonwealth of Pennsylvania. These guidelines are intended primarily for use by responsible officials of local governments to formulate highway design criteria, policies and procedures within the appropriate jurisdictional highway classification that does not constitute the State highway system network. Initiative should be exercised to utilize the most appropriate design values within the given ranges based upon the project context and roadway typology wherever practicable and within reasonable economic limitations and sound engineering judgment. In restricted or unusual conditions, these guide values may not be achievable. Every effort should be made to obtain proper drainage and the best possible alignment, grade and sight distance that are consistent with the terrain, development (present and anticipated), safety and available funding. These factors should be recognized before any modifications are made that introduce design exception features. This Publication does not attempt to encompass the total scope of important, published information and literature relative to the formulation of highway design criteria, policies and procedures. Sources of additional publications and related material, which should complement the concepts contained herein, are presented in Appendix B. Since safety is an important factor in all roadway projects, these guidelines were developed giving number one priority to the safety of pedestrians, bicyclists and the motoring public. Pedestrians are a part of every roadway environment and attention must be paid to their presence in urban as well as rural areas. Pedestrian access, safety and needs must be given full consideration during the planning and design of all transportation projects. The Americans with Disabilities Act (ADA) of 1990 is a civil rights statute that prohibits discrimination against people with disabilities. ADA implementing regulations for Title II prohibit discrimination in the provision of services, programs, and activities by state and local governments. Designing and constructing pedestrian facilities in the public right-of-way that are not usable by people with disabilities may constitute discrimination. Section 504 of the Rehabilitation Act of 1973 (504) includes similar prohibitions in the conduct of federally-funded programs. ADA accessibility provisions apply to the entire transportation project development process including planning, design, construction and maintenance activities. However, it may not be practical or possible to obtain obstacle-free roadside areas. Therefore, every effort should be made to provide as much clear roadside width as is practical. This becomes more important as speeds increase. The specific design values and criteria applicable to the local rural road system are presented in Chapter 2 while those applicable to the local urban road system are presented in Chapter 3. The policy of the Pennsylvania Department of Transportation * regarding local roads and streets is presented in these guidelines. However, it should be recognized that the contents contained herein are guidelines and that there are certain conditions which shall require individual consideration. Where a short segment of roadway must be relocated, a higher type design shall not be approved unless the municipality guarantees a definite schedule for similar improvements to the adjacent sections of the roadway. If local officials do not concur in writing to the above, the Department policy shall be to replace in kind. The inclusion of specified design criteria in this Publication does not imply that existing facilities, which were designed and constructed using different criteria, are either substandard or must be reconstructed to meet the criteria contained herein. Many existing facilities, which met the design criteria at the time of their construction, are adequate to safely and efficiently accommodate current traffic demands. * Hereinafter referred to as the Department. 1-1

15 Chapter 1 - General Design Guidelines Since it is not feasible to provide a highway system that is continuously in total compliance with the most current design criteria, it is imperative that both new construction and reconstruction projects are selected from a carefully planned program which identifies those locations in need of improvement and then treats them in priority order. Once a new construction or reconstruction project is selected in this manner, this Publication shall be used in determining the appropriate design criteria. Department-owned roadways provide local roads and driveways with access. Publication 282, Highway Occupancy Permit (HOP) Guidelines, describes laws, regulations, policies, and procedures relating to access for local roads and driveways onto facilities owned by the Department. These guidelines were prepared to assist and provide applicants with general instructions when applying for a Highway Occupancy Permit relating to placing or modifying an access and opening the highway surface. Policies are discussed for situations where Department-owned roadways are reconstructed because an existing access is modified or a new access is provided. Permit applications involving a local road, a medium volume driveway, or a high volume driveway would include the submission of a Traffic Impact Study to the Department for review and approval. 1.1 LAND USE CONTEXT AND ROADWAY TYPOLOGIES Each project's scope shall be based on the well-defined needs that must be addressed. The needs are based upon the most pressing transportation problems in the project area. The scope of work shall be used to determine the appropriate design criteria for all projects. A determination of the roadway's typology should be identified early in project design based on a project's land use context, as well as the functional classification of the roadway. A. Land Use Context. Seven context areas are described below, from the least to the most developed: 1. Rural. This context area consists of a few houses and structures dotting a farm or forest landscape. The areas are predominantly natural wetlands, woodlands, meadow or cultivated land. Small markets, gas stations, diners, farm supplies, convenience grocers, etc. are often seen at the intersections of arterial or collector roads. Rural areas also may include a few commercial or civic uses and a number of homes close to the roadway. 2. Suburban Neighborhood. This area is predominantly low-density residential communities. House lots are typically arranged along a curvilinear internal system of streets with limited connections to regional road network or surrounding streets. Lot sizes are usually 0.8 ha (2 acres) to 0.1 ha (0.25 acre), but in older suburbs, it is common to find 0.05 ha (0.125 acre) lots. Garden apartments are also included in this type. Neighborhoods can include community facilities such as schools, churches, recreational facilities, and some stores and offices. When suburban houses line an arterial roadway but have their primary access to frontage roads or rear access roads, it is possible to classify this area as a "suburban corridor". 3. Suburban Corridor. This area is characterized by big box stores, commercial strip centers, restaurants, auto dealerships, office parks, and gas stations. These uses are sometimes interspersed with natural areas and occasional clusters of homes. Buildings are usually set back from the roadway behind surface parking. Office buildings are usually set back a bit more than adjacent retail frontage to establish garden separation from ground windows. 4. Suburban Center. This area is often a mixed-use, cohesive collection of land uses that may include residential, office, retail, and restaurant uses where commercial uses serve surrounding neighborhoods. These areas are typically designed to be accessible by car, and may include large parking areas and garages. They are less accommodating to pedestrians than town centers, and opportunities to cross the primary roadway can be limited. On-street parking may or may not be provided. 5. Town/Village Neighborhood. This area is predominantly residential neighborhoods, sometimes mixed with retail, restaurants, and offices. In urban places, residential buildings tend to be close to the street. Rowhouses fronting the sidewalk, and houses back 9 m (30 ft) behind a front lawn are both common types. Small retail establishments sometimes occupy principal corners. Block sizes are regular and often small in comparison to suburban neighborhood blocks. Even where streets are narrow, on-street parking is common and typically well used. The large majority of neighborhoods have sidewalks. 1-2

16 Chapter 1 - General Design Guidelines 6. Town/Village Center. This area is a mixed use, high density area with buildings adjacent to the sidewalk, typically two to four stories tall with commercial operations on the ground floor and offices or residences above. Parallel parking usually occupies both sides of the street with parking lots behind the buildings. Important public buildings, such as the town hall or library, are provided special prominence. 7. Urban Core. These areas are downtown areas consisting of blocks of higher density, mixed use buildings. Buildings vary in height from three to over 60 stories with most buildings dating from an era when elevators were new technology - so five to twelve stories were the standard. B. Roadway Typologies. Roadway typology captures the role of the roadway within its context, focusing on characteristics of access, mobility, and speed. The Roadway Typologies are illustrated in Table 1.1 and Figure 1.1. The roadway classes shown in Table 1.1 correspond to the classifications of arterial, collector, and local, as described in the publication, A Policy on Geometric Design of Highways and Streets *. Once the roadway typology is determined, the appropriate design criteria can be selected. See Chapters 2 and 3 for guidance. As stated in Section 1.0 above, initiative should be exercised to utilize the most appropriate design values within the given ranges based upon the project context and roadway typology wherever practicable and within reasonable economic limitations and sound engineering judgment. ROADWAY CLASS Arterial Arterial Collector Collector Local ROADWAY TYPE Regional Community Community Neighborhood Local DESIRED OPERATING SPEED km/h (30-55 mph) km/h (25-55 mph) km/h (25-55 mph) km/h (25-35 mph) km/h (20-30 mph) TABLE 1.1 ROADWAY TYPOLOGIES AVERAGE TRIP LENGTH km (15-35 mi) km (7-25 mi) 8-16 km (5-10 mi) < 11 km (< 7 mi) < 8 km (< 5 mi) VOLUME 10,000-40,000 veh/day 5,000-25,000 veh/day 5,000-15,000 veh/day < 6,000 veh/day < 3,000 veh/day INTERSECTION SPACING m (660-1,320 ft) m (300-1,320 ft) m ( ft) m ( ft) m ( ft) COMMENTS Roadways in this category would be considered "Principal Arterial" in traditional functional classification. Often classified as "Minor Arterial" in traditional classification but may include road segments classified as "Principal Arterial". Often similar in appearance to a community arterial. Typically classified as "Major Collector". Similar in appearance to local roadways. Typically classified as "Minor Collector". * Hereinafter referred to as the Green Book. 1-3

17 Chapter 1 - General Design Guidelines FIGURE 1.1 ILLUSTRATED ROADWAY TYPOLOGIES 1-4

18 Chapter 1 - General Design Guidelines FIGURE 1.1 (CONTINUED) ILLUSTRATED ROADWAY TYPOLOGIES 1-5

19 Chapter 1 - General Design Guidelines BLANK PAGE 1-6

20 Chapter 2 - Local Rural Road System CHAPTER 2 LOCAL RURAL ROAD SYSTEM 2.0 INTRODUCTION The guidelines presented herein for the local rural road system utilize the concept of roadway typologies, as described in Chapter 1, Section 1.1. A determination of the roadway's typology should be identified early in project design during the scoping field view process based on a project's context, as well as the functional classification of the roadway. In addition to Section 1.1, refer to Table 1.1 and Figure 1.1 for additional details about the roadway typologies. The roadways that comprise the functional classification system differ for urban and rural areas. The hierarchy of the functional classification systems consists of Interstate and Other Limited Access Freeways, Principal and Minor Arterials, Major and Minor Collectors and Local Roads. These systems for the entire rural area system and their associated service characteristics are presented in Figure 2.1. There are three general functional classifications established for the local rural road system: (1) Arterials, (2) Collectors and (3) Local Roads. Municipalities may own roads that fall under any or all of these three general functional classifications. Almost all local road systems will fall into the Collector or Local Roads category with the majority being Local Roads. The Arterial classification includes highways which provide connections between boroughs, larger villages, major resort areas and other traffic generators which develop substantial volumes of traffic where the average trip lengths are usually 11 km (7 mi) or greater. The Collector classification includes highways that provide connections with local roads, arterials and the State highway system network. These roads may serve a traffic corridor connecting villages, small boroughs, shipping points, mining and agricultural areas on an intra-county or township basis. Many trips destined to such points originate in widely diffused locations and a highway in this classification is considered as a collector. Traffic volumes and trip lengths vary greatly depending upon size and distance between localities. The Local Road classification provides direct access to adjacent land and includes connections from farms, individual residences and commercial properties to higher functional classification systems. Trip lengths are short and operating speeds are low. Spacing between roads of this classification and traffic volumes vary considerably depending on the intensity of land development and the distance to population centers. In general, this classification includes all public roads which are not included in higher classifications. 2.1 DESIGN AND CROSS SECTION ELEMENTS There are many factors that contribute to the decisions required for the geometric design and cross section elements utilized in the location and design of the rural road system. Without some type of basic framework of design controls, the judgment of the individual designers may vary considerably. This section presents the guidelines and concepts that should be considered when designing features of the local rural road system. A. Terrain. The topography of the land traversed has an influence on the vertical and horizontal alignments of roadways and streets. To characterize variations, topography is separated into three classifications according to terrain: (1) level terrain, (2) rolling terrain and (3) mountainous terrain. In level terrain, highway sight distances, as governed by both horizontal and vertical restrictions, are generally long or can be made to be so without construction difficulty or major expense. In rolling terrain, natural slopes consistently rise above and fall below the road or street grade, and occasional steep slopes offer some restriction to normal horizontal and vertical roadway alignment. 2-1

21 Chapter 2 - Local Rural Road System INTERSTATE AND OTHER LIMITED ACCESS FREEWAYS FIGURE 2.1 FUNCTIONAL CLASSIFICATION SYSTEM SERVICE CHARACTERISTICS RURAL AREA SYSTEM 1. Provides limited access facilities. ARTERIALS COLLECTORS LOCAL ROADS PRINCIPAL ARTERIALS MINOR ARTERIALS MAJOR COLLECTORS MINOR COLLECTORS 1. Serves statewide or interstate level. 2. Serves all urbanized areas. 3. Provides integrated movements without stub connections. 1. Links cities, larger towns and other traffic generators. 2. Provides integrated interstate and inter county service. 3. Spaced at proper intervals consistent with population density. 4. Corridor movements consistent with 1. through 3. with greater trip lengths and travel densities than those served by rural collector or local systems. 1. Provides service to county seats, larger towns and other traffic generators. 2. Connects routes of higher classification. 3. Serves intracounty travel corridors. 1. Spaced at intervals to collect traffic from local roads. 2. Provides services to remaining smaller communities. 3. Links local traffic generators with rural hinterland. 1. Provides access to land adjacent to collector network. 2. Serves travel over relatively short distances. 3. Constitutes all rural roads not classified in one of the higher systems. 2-2

22 Chapter 2 - Local Rural Road System In mountainous terrain, longitudinal and transverse changes in the elevation of the ground with respect to the road or street are abrupt, and benching and side hill excavation are frequently needed to obtain acceptable horizontal and vertical roadway alignment. Terrain classifications pertain to the general character of a specific route corridor and not to the land form surrounding the project area. Routes in valleys, passes or mountainous areas that have all the characteristics of roads or streets traversing level or rolling terrain should be classified as level or rolling. In general, rolling terrain generates steeper grades than level terrain, causing trucks to reduce speeds below those of passenger cars; and mountainous terrain has even greater effects, causing some trucks to operate at crawl speeds. B. Alignment. Where curvature in the highway alignment between control points is required, the appropriate relationship should be established between design speed and curvature on their joint relationships with superelevation and side friction. Alignment between control points should be designed to be as favorable as possible consistent with the environmental impacts, topography, terrain, design traffic volume and the amount of reasonably obtainable right-of-way. Sudden changes between curves of widely different radii or between long tangents and sharp curves should be avoided. Where practical, the design should include passing opportunities. Where crest vertical curves and horizontal curves occur together, there should be greater than minimum sight distance to ensure that the horizontal curves are visible to approaching drivers. Horizontal and vertical alignments are permanent design elements for which thorough study is warranted. They should not be designed independently, but should complement one another to avoid alignment deficiencies. Excellence in the design of each and of their combination increases usefulness and safety, encourages uniform speed and improves appearances on which to travel. Coordination of horizontal and vertical alignment should begin with the preliminary design at which time adjustments can be readily made. Design speed may have to be adjusted during the process along some sections to conform to likely variations in speeds of operation due to changes in alignment characteristics that are needed to accommodate unusual terrain, railroad-highway grade crossings or right-of-way controls. All aspects of terrain, traffic operation and appearance should be considered and the horizontal and vertical lines should be adjusted and coordinated before the calculations and the preparation of construction plans to large scale are started. For additional information concerning general design considerations and the practical application of relevant criteria for both horizontal and vertical alignments, refer to the Department's Publication 13M, Design Manual, Part 2, Highway Design, Chapter 2, Sections 2.1, 2.2 and 2.3. C. Sight Distance. Sight distance is the distance along a roadway throughout which an object of specified height is continuously visible to the driver. The available sight distance on a roadway should be sufficiently long to enable a vehicle traveling at or near the design speed to stop before reaching a stationary object in its path. Two-lane rural highways should generally provide passing sight distance at frequent intervals and for substantial portions of their length. The criteria for measuring sight distance are dependent on the height of the driver's eye above the road surface, the specified object height above the road surface and the height and lateral position of sight obstructions within the driver's line of sight. For calculating both stopping and passing sight distances, the height of the driver's eye above the road surface shall be considered as m (3.5 ft). For stopping sight distance calculations, the height of object shall be considered as m (2.0 ft) above the road surface. For passing sight distance calculations, the height of object shall be considered as m (3.5 ft) above the road surface. On a tangent roadway, the obstruction that limits the driver's sight distance is the road surface at some point on a crest vertical curve. On horizontal curves, the obstruction that limits the driver's sight distance may be the road surface at some point on a crest vertical curve, or it may be some physical feature outside of the traveled way, such as a longitudinal barrier, a bridge-approach fill slope, a tree, foliage or the backslope of a cut section. Accordingly, all highway construction plans should be checked in both the vertical and horizontal plane for sight distance obstructions. For additional information relative to sight distance, refer to the Department's Publication 13M, Design Manual, Part 2, Highway Design, Chapter 2, Section

23 Chapter 2 - Local Rural Road System D. Superelevation. Superelevation is predicated on design speed and all highways shall be superelevated according to their speeds rather than using a superelevation for a single radius for all design speeds. Maximum superelevation should be limited to 8.0% and shall be dependent on the design speed and the radius. For additional information relative to superelevation, refer to the Department's Publication 13M, Design Manual, Part 2, Highway Design, Chapter 2, Section E. Grades and Radii. The maximum grades and minimum radii required for the various design speeds are discussed in the Department's Publication 13M, Design Manual, Part 2, Chapter 2, Highway Design, Sections 2.6 and 2.7. F. Pavement Design. The selection of pavement type required is determined based on the traffic volume and composition, soil characteristics, weather, performance of pavements in the area, availability of materials, energy conservation, initial cost and the overall annual maintenance and service-life cost. The design policies, guidelines and procedures for the construction, restoration, rehabilitation, resurfacing and reconstruction of pavement structures on all Department projects shall conform to the requirements specified in the Department's Publication 242, Pavement Policy Manual. All components of the pavement structure shall be applied in accordance with the requirements specified in the Department's Publication 408, Specifications. The Department's Publication 242, Pavement Policy Manual, provide guidelines for the minimum and maximum depths of materials needed in the pavement structure for the various functional classifications of highways. Note that these depths are based on minimum performance requirements and material properties. Site specific designs shall be performed for each project to determine appropriate pavement layers. When Superpave wearing course is used as a scratch or leveling course, refer to the Department's Publication 242, Pavement Policy Manual, for guidance. On non-interstates do not place Superpave Hot Mix Asphalt (HMA) Wearing Course overlays with a thickness less than 40 mm (1.5 in) without meeting the following circumstances: The existing pavement surface is bituminous. The existing pavement is structurally sound; less than 2% of the pavement requires patching. Surface drainage is good, or will be upgraded to good, with this project. Subsurface drainage is good, or will be upgraded to good, with this project. No structural upgrade of the pavement is required. For paving dates restrictions (due to weather limitations) refer to Publication 408, Specifications, Section 409.3(b). Cities, Boroughs or Townships that have resurfacing projects on State Routes shall follow the policies, guidelines and procedures indicated in the above-referenced Department publications. When Cities, Boroughs or Townships undertake pavement projects on local roadways under their own jurisdiction, the pavement alternates and minimum and maximum depths in the pavement structure that are indicated in the Department's Publication 242, Pavement Policy Manual, may be used as a guide for the applicable highway functional classification. In addition, the AASHTO publication, Guide for Design of Pavement Structures, should be used as a guide for the selection of pavement structures deemed appropriate for the specific circumstances. G. Guide Rail. Highways should be designed through judicious arrangement and balance of geometric features to preclude or minimize the need for guide rail. To provide for maximum roadside safety, a thorough study during the early stages of design is necessary to recognize and eliminate, where practical, those items and conditions which require guide rail. GUIDE RAIL SHOULD ONLY BE USED WHERE THE RESULT OF STRIKING THE OBJECT OR LEAVING THE ROADWAY WOULD BE MORE SEVERE THAN THE CONSEQUENCE OF STRIKING THE GUIDE RAIL. Where guide rail is required, the roadway should be examined to determine the feasibility of adjusting site features so that the guide rail can be eliminated (e.g., flattening an embankment slope, removing a fixed object or eliminating a drainage head wall). The initial cost to eliminate the guide rail may appear excessive; however, a guide rail installation requires maintenance for many years and this fact should not be overlooked. 2-4

24 Chapter 2 - Local Rural Road System Height and slope of the embankment are the basic factors to determine barrier requirements. The criteria for guide rail protection on embankments are presented in Table 2.1. Rounding at the shoulder and at the toe of an embankment can reduce the severity of run-off-the-road crashes. A rounded slope should reduce the chances of an errant vehicle becoming airborne, and should afford the driver more control over the vehicle. In view of the safety benefits, rounding should be considered in the design process. Consideration should be given to eliminating short lengths of guide rail since these sections are often more undesirable than no section at all. Where guide rail cannot be eliminated, it shall be a minimum of 15 m (50 ft) plus proper end treatment. Avoid short gaps between guide rail installations. If the points of need are determined to be about 60 m (200 ft) apart or less, the guide rail protection should be made continuous between them. Provide end treatments, as shown in Publication 72M, Roadway Construction Standards, on both the approach and trailing ends of the guide rail on two-lane highways with two-way traffic. On four-lane divided highways, end treatments shall be used on the approach ends only, except that for anchoring purposes, end treatments are required on all ends of weak post guide rail. Extend guide rail systems (on the approach side) beyond the required limits to prevent vehicle access behind the protective guide rail system. On two-lane highways, both ends of the guide rail are considered the approach ends. For further information relative to guide rail installations, refer to the Department's Publication 13M, Design Manual, Part 2, Highway Design, Chapter 12; Publication 72M, Roadway Construction Standards; and the AASHTO Roadside Design Guide. 2.2 DESIGN CONTROLS This section presents the guidelines and concepts that should be considered when designing control features of the local rural road system. A. Design Traffic Volumes. A design traffic volume is referred to as the average daily traffic (ADT) volume which is the total volume during a given time period (in whole days), greater than one day and less than one year divided by the number of days in that time period. The development of the ADT for a specific highway requires a detailed analysis of many traffic counts, future land use and development, future trends in transportation modes, etc. New highways or improvements to existing highways should not usually be based on current traffic volumes alone, but should consider future traffic volumes expected to use the facility. A period of 20 years should be used as the basis for design. For reconstruction or rehabilitation projects, estimating traffic volumes for a 20-year design period may not be appropriate because of the uncertainties of predicting traffic and funding constraints. A shorter design period (5 to 10 years) may be developed for such projects. B. Design Speed. Design speed is a selected speed used to determine the various geometric features of the roadway. The assumed design speed should be a logical one with respect to the topography, anticipated operating speed, the adjacent land use, and the functional classification of the highway. The selected design speed should be consistent with the speeds that drivers are likely to expect on a given highway facility. Where a reason for limiting speed is obvious, drivers are more apt to accept lower speed operation than where there is no apparent reason. A highway of higher functional classification may justify a higher design speed than a lesser classified facility in similar topography, particularly where the savings in vehicle operation and other operating costs are sufficient to offset the increased costs of right-of-way and construction. A low design speed, however, should not be selected where the topography is such that drivers are likely to travel at high speeds. Drivers do not adjust speeds because the highway is called out as a local road or an arterial. Drivers base their speeds on what physical highway they see and the traffic surrounding them. 1. Projects with New or Modified Speed Posting. For projects on new location, or projects where the desired operating speed differs from the current posted speed on the roadway, the design speed should be selected with respect to the topography, anticipated operating speed, the adjacent land use, and the functional classification of the highway. The geometric features of the roadway should be designed appropriately, consistent with the established design speed, to encourage the appropriate operating speed. The design speed shall not be less than the anticipated post-construction regulatory speed limit. 2-5