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Report Access Management Plan City of Middleton, WI December 2006 ---PAGE BREAK--- ---PAGE BREAK--- Report for City of Middleton, Wisconsin Access Management Plan Prepared by: Traffic Associates LLC and STRAND ASSOCIATES, INC.® 910 West Wingra Drive Madison, WI 53715 www.strand.com December 2006 Approved by Middleton City Council November 21, 2006 ---PAGE BREAK--- ---PAGE BREAK--- S:\@SAI\001--050\024\005\Wrd\FINAL DOCUMENTS - TMP\FINAL - December 2006\Access Management - COMPLETE\TOC.doc\12/11/2006 TABLE OF CONTENTS Page No. or Following SECTION 1–GENERAL 1.01 1-1 SECTION 2–ACCESS MANAGEMENT 2.01 Principles of Access 2-1 TABLES 1.01-1 Crash Rates by Number of Access Points and Type of Median in Urban and Suburban Areas 1-2 1.01-2 Access Frequency Impact on Traffic Speed 1-2 2.01-1 Driveway Spacing 2-5 2.01-2 Median Spacing 2-5 2.01-3 Recommended Minimum Driveway Throat 2-9 FIGURES 1.01-1 Functional Street System 1-1 2.01-1 Example of Limiting Access to Non-Arterial Streets 2-2 2.01-2 Shared Access 2-4 2.01-3 Intersection Functional Area 2-6 2.01-4 Intersection Conflict Points 2-6 2.01-5 Corner Clearance Criteria at Controlled Intersections 2-7 2.01-6 Nonresidential Driveway Design 2-8 2.01-7 Driveway Design Examples 2-9 2.01-8 Driveway Vision Corners on Arterial 2-10 ---PAGE BREAK--- ---PAGE BREAK--- SECTION 1 GENERAL ---PAGE BREAK--- ---PAGE BREAK--- City of Middleton, Wisconsin Access Management Plan Section 1–General Prepared by Strand Associates, Inc.® 1-1 Figure 1.01-1 Functional Street System Mobility 1.01 OVERVIEW Access management is a tool to balance transportation system mobility (defined by safety and efficiency) with the access rights of property owners. All properties have the right to access a community’s transportation system. The degree of accessibility will vary by functional classification of the adjacent street based on the intended balance of serving mobility and accessibility needs as shown in Figure 1.01-1. Arterial Streets are intended primarily to provide transportation mobility for through-traffic movements under safe and efficient operating conditions with limited direct access to adjacent land uses. Arterial streets accommodate long-trip patterns and typically carry traffic volumes ranging from 10,000 to 35,000 vehicles per day (vpd). Collectors serve to collect trips from the local street system and route them to the arterial system, as well as provide access to individual properties. Trips on collectors are shorter in length than found on arterials, with traffic volumes typically ranging from 1,000 to 10,000 vpd. In comparison, the primary purpose of local streets is to provide direct access to adjacent properties while maintaining traffic safety. Traffic volumes on local streets in urban areas are generally below 1,000 vpd. Access management studies have documented that controlling access to adjacent land uses improves traffic safety and operational efficiency as shown in Tables 1.01-1 and 1.01-2. ---PAGE BREAK--- City of Middleton, Wisconsin Access Management Plan Section 1–General Prepared by Strand Associates, Inc.® 1-2 Median Type Access Points per Mile Undivided Two-way Left-Turn Lane Nontraversable < 20 3.8 3.4 2.9 20.1 – 40 7.3 5.9 5.1 40.1 – 60 9.4 7.9 6.8 > 60 10.6 9.2 8.2 Table 1.01-1 Crash Rates by Number of Access Points and Type of Median In Urban and Suburban Areas (Crashes per Million Vehicle-Miles Traveled) Source: FHWA Access Management Manual Access Points Per Mile Reduction in Free-Flow Speed 0 0.0 10 2.5 20 5.0 30 7.5 40 or more 10.0 Table 1.01-2 Access Frequency Impact on Traffic Speed Source: FHWA Access Management Manual. As shown in Table 1.01-1, the number of crashes per million miles traveled more than doubles when the number of driveway access points per mile increases from less than 20 to more than 40. Similarly, Table 1.01-2 shows that free-flow speeds on arterials and collectors are reduced by 5 mph with 20 access points per mile and by 10 mph on streets with 40 or more access points per mile. ---PAGE BREAK--- SECTION 2 ACCESS MANAGEMENT ---PAGE BREAK--- ---PAGE BREAK--- City of Middleton, Wisconsin Access Management Plan Section 2–Access Management Prepared by Strand Associates, Inc.® 2-1 2.01 PRINCIPLES OF ACCESS MANAGEMENT Access management programs seek to limit and consolidate access points along arterial and collector streets while promoting the use of the supporting local street system for access to developments. Access management controls will vary by the functional classification of a street. The principles of access management, however, are the same for all functional street classifications. The four major principles of access management are as follows: 1. Minimize the number of access points. 2. Separate conflict areas. 3. Minimize acceleration/deceleration requirements. 4. Remove turning vehicles from through-traffic lanes. As previously shown in Tables 1.01-1 and 1.01-2, minimizing the number of access points reduces traffic conflict locations along a roadway, improving safety and traffic flow conditions. The separation of conflict areas directly reduces the number of conflict points, the overlapping of traffic movements between conflict areas, and the footprint of conflict areas by limiting vehicle maneuvers at or between adjacent access points. A reduction in vehicle acceleration/deceleration requirements along a street reduces the severity of conflicts by allowing vehicles entering or exiting a roadway to more closely match through-traffic speeds. Finally, the removal of turning vehicles from through-traffic lanes reduces the severity of conflicts by providing storage areas and exclusive channelization for turning movements. In addition to controlling the spacing and frequency of driveway access points along arterial or collector streets, it is equally important to control the design of driveways. The four factors that are considered critical to sound driveway design are: 1. Throat width 2. Throat length 3. Curb radii 4. Vision corners These considerations are necessary to minimize adverse effects from vehicle conflicts, backups, and vehicle acceleration/deceleration requirements at each driveway access location. The sound application of these principles will: Reduce crashes. Maximize existing street capacity. Preserve the public investment in transportation infrastructure. Reduce the need to widen or build new streets. Protect the value of private investments. ---PAGE BREAK--- City of Middleton, Wisconsin Access Management Plan Section 2–Access Management Prepared by Strand Associates, Inc.® 2-2 Arterial Street Arterial Street Figure 2.01-1 Example of Limiting Access to Nonarterial Streets A. Access Location The goals of access location management are to limit the number of driveways along a street, the spacing between driveways, and their proximity to intersections. Therefore, access location management is divided into three elements: limiting property access to the lowest functionally classified street; limiting access spacing along street segments between intersections; and limiting access along the approaches to intersections. 1. Limit Access to Lowest Functionally Classified Street Access to arterial streets (and collector streets where possible) should be minimized by requiring access connections to adjacent lower functionally classified streets. Arterial streets are functionally classified to carry high traffic volumes, operate at higher traffic speeds, and serve primarily through traffic. This criteria is typically applied to corner properties with frontage on arterial street and other local streets. With a good urban street network design, this criteria can also be applied to other properties not directly located at street intersections by providing access to minor streets at the rear of lots. If a property can receive access from an adjacent street with a lower functional classification it should not be granted access from the higher functionally classified street. In this manner, traffic access conflicts are shifted to the lower functionally classified street, which will typically have lower volumes and speeds and provide safer conditions. Figure 2.01-1 illustrates an example of requiring driveway access from lower level functionally classified streets. As shown in the Figure 2.01-1, the number of access points is reduced from eight to two along the south side of the east-west arterial street corridor. ---PAGE BREAK--- City of Middleton, Wisconsin Access Management Plan Section 2–Access Management Prepared by Strand Associates, Inc.® 2-3 2. Limit Street Segment Driveway Spacing Driveways should be sufficiently spaced to minimize conflicts from adjacent driveway movements and from through traffic on the adjacent street system. Control of driveway spacing generally requires consideration of the following two criteria: properties should be limited to the fewest possible access points and access spacing should be controlled to minimize traffic conflicts. a. Limit Number of Property Access Points Each single-family residential property should be permitted only one driveway. These properties do not generate high traffic volumes and present minimal conflicts with local street traffic movements. For commercial properties, the number of access points that should be allowed depends on the length of property frontage along an arterial or collector street and the volume of traffic generated by the development. A general rule of thumb requires a property to generate more than 500 trips per hour (typically equivalent to 5,000 trips per day) to justify more than one driveway. Should a property generate this high volume of trips, a second driveway may be considered if its frontage exceeds 600 feet. Three driveways may be considered if the development’s frontage exceeds 1,300 feet. A second or third access driveway should only be granted if a traffic impact study for the property indicates a need for two or three access driveways to maintain traffic flow on the street. On a median-divided street, a second driveway can be approved but limited to right-turn entering and exiting movements. If more than one access driveway is required for a major traffic generating property, then the criteria for control of the access spacing should be applied. On some properties it may be possible to minimize the number of access points by sharing access between adjacent properties. This can be accomplished by encouraging cross easements between adjacent properties and parking circulation designs that accommodate ingress/egress traffic patterns to both properties. Figure 2.01-2 illustrates an example of shared access control between two adjacent properties and how access to four different properties can be reduced to two driveways through shared access. ---PAGE BREAK--- City of Middleton, Wisconsin Access Management Plan Section 2–Access Management Prepared by Strand Associates, Inc.® 2-4 Figure 2.01-2 Shared Access Examples Source: FHWA Access Management Manual b. Control Access Spacing Driveways should be adequately spaced to limit traffic entrance/exit maneuver conflicts between driveways. Each driveway should be located based on its proximity to adjacent driveways, driveways on the opposite side of the street, and if the street is median-divided, its proximity to a median opening. Table 2.01-1 illustrates minimum recommended driveway spacing criteria based on the posted speed limit of the arterial or collector street. ---PAGE BREAK--- City of Middleton, Wisconsin Access Management Plan Section 2–Access Management Prepared by Strand Associates, Inc.® 2-5 Posted Speed (mph) Driveway Spacing (Center to Center) 25 105 feet 30 125 feet 35 150 feet 40 185 feet Table 2.01-1 Driveway Spacing Criteria Source: FHWA Access Management Manual Posted Speed (mph) Median Opening Spacing 25 300 feet 30 370 feet 35 460 feet 40 530 feet Table 2.01-2 Median Spacing Criteria Source: FHWA Access Management Manual. The application of the minimum spacing requirement assumes that a property has sufficient frontage to provide the required spacing. When a property does not have sufficient frontage along a street or the ability to share access with adjacent properties to meet this criterion, each property can be granted an individual access driveway. Under the above condition, access should be located to maximize spacing between adjacent property driveways. On median-divided streets, driveways should be located to align with existing or planned median openings or be sufficiently located away from the median opening to account for a future driveway to be located at the median opening. This is required to minimize median-traffic movement conflicts with adjacent driveway movements. Table 2.01-2 illustrates minimum recommended median opening spacing requirements based on posted speeds for arterial and collector streets with nonresidential development land uses. For undivided streets, driveways on opposite sides of the street should be located across from each other, be spaced at least 150 feet apart for driveways to minor generators, or 300 feet apart for driveways to major generators. Minor generators are defined as developments that generate less than 5,000 trips per day. Major generators are defined as developments that generate greater than 5,000 trips per day. For arterial and collector streets with residential land uses, it is typically not feasible to provide 150- foot driveway spacing because of limited property frontage widths. Under this condition, spacing requirements of residential driveways on opposite sides of the street that cannot be located across from one another are reduced to 50 feet. ---PAGE BREAK--- City of Middleton, Wisconsin Access Management Plan Section 2–Access Management Prepared by Strand Associates, Inc.® 2-6 Figure 2.01-3 Intersection Functional Area Source: FHWA Access Management Manual. Figure 2.01-4 Intersection Conflict Points Source: FHWA Access Management Manual 3. Limit Intersection Approach Clearance The location of access driveways in proximity to street intersections should avoid the functional area of an intersection. The functional area of an intersection varies based on traffic queuing on the approaches to an intersection as well as traffic flow characteristics on each of the legs exiting an intersection. Figure 2.01-3 shows the general functional area of an intersection. Traffic movements entering or exiting driveways within an intersection’s functional area add conflict points to the intersection. As shown in Figure 2.01-4, a standard four-leg intersection has a total of 32 conflict points without any conflicts from nearby driveway traffic movements. Turning movements at a driveway located within an intersection’s functional area complicate driving activity and can lead to crashes. Driveway movements can also be blocked by vehicles queued at an intersection approach resulting in driver delays and frustration, which can also lead to increased crashes. ---PAGE BREAK--- City of Middleton, Wisconsin Access Management Plan Section 2–Access Management Prepared by Strand Associates, Inc.® 2-7 Clearance Type Adjacent to Access Intersection Capacity Posted Speed Min. Corner Clearance A – Upstream on Major Street B – on Major Street C – Approach Side on Minor Street D – Departure Side on Minor Approach 20 mph 30 mph 40 mph 50 mph 30 mph 40 mph 50 mph 20 mph 30 mph 40 mph 50 mph 115 feet plus queue storage 270 feet plus queue storage 420 feet plus queue storage 610 feet plus queue storage 200 feet 305 feet 425 feet 100 feet 50 feet 100 feet 75 feet 50 feet plus queue storage 115 feet 225 feet 365 feet 535 feet 50 vph, ~500 ADT 100 vph, ~1,000 ADT < 100 vph (Stop control with high cross traffic) > 100 vph (Stop control with low cross traffic) <100 vph (Stop control with high cross traffic) <200 vph (Stop control with low cross traffic) >200 vph (Signal Control) Volume in Lane Figure 2.01-5 Corner Clearance Criteria at Controlled Intersections Source: FHWA Access Management Manual Figure 2.01-5 provides recommended minimum driveway spacing criteria for the approaches to intersections controlled by stop signs or traffic signals. ---PAGE BREAK--- City of Middleton, Wisconsin Access Management Plan Section 2–Access Management Prepared by Strand Associates, Inc.® 2-8 Figure 2.01-6 Nonresidential Driveway Design Elements Source: FHWA Access Management Manual. B. Driveway Design Driveway design has a major effect on street traffic operation and on property traffic circulation patterns. Conflicts between entering and exiting driveway traffic, both left- and right-turn movements, with street through-traffic movements can increase traffic delays and crashes. Poor parking lot traffic circulation can directly affect street traffic operating conditions by slowing or queuing vehicles into street traffic. Figure 2.01-6 illustrates some of the major driveway design elements for nonresidential land uses. 1. Driveway Throat Width Driveway throat width and curb radii are related and control vehicle entering speeds that can affect through-traffic movements on the street. Driveway width also affects pedestrians and bicyclists. Narrow driveways serve to minimize the conflict zones between vehicles and crossing pedestrians or bicyclists. Studies have shown the driveway throat width on single-entry lanes should be 14 feet. The driveway throat width of 14 feet permits an entering vehicle to maintain a reasonable speed when entering the development. Only when two lanes are required for movements into a major traffic generating development, or additional width is required to accommodate regular trucking access to manufacturing or light industrial development, should a driveway be widened beyond the recommended maximum single-entrance lane width of 16 feet. Driveway exit lane widths should be a minimum of 10 feet unless a traffic impact study shows a need for additional lanes. Whether signed or not, Wisconsin Statutes require drivers to stop in the driveway prior to entering the street. If two lanes are required for operational purposes to minimize driveway queuing or to separate right-turn vehicles from through or left-turn exit ---PAGE BREAK--- City of Middleton, Wisconsin Access Management Plan Section 2–Access Management Prepared by Strand Associates, Inc.® 2-9 = poor design = good design Figure 2.01-7 Driveway Design Examples Land Use Parking Spaces per Exit Lane Multifamily Retail Office Industrial 0-200 25 feet 25 feet 25 feet 50 feet 201-400 25 feet 50 feet 100 feet 150 feet 401-600 50 feet 150 feet 200 feet add lanes 601-700 100 feet 200 feet add lanes > 701 200 feet add lanes Table 2.01-3 Recommended Minimum Driveway Throat Length Source: Report 348, Access Management Guidelines for Activity Centers movements, the exit lanes should be 10 to 12 feet wide and separated from entering traffic by a raised median with a minimum width of 4 feet. The median width is necessary to protect traffic control signage that may be located within it. 2. Driveway Throat Length As shown in Figure 2.01-6, driveway throat length is the distance between parking lot circulation activity and the street curb. Parking space activity and site circulation roadways should be separated from traffic entering or exiting the driveway to avoid the overlapping driveway entrance and parking lot circulation conflicts as shown in Figure 2.01-7. The standards shown in Table 2.01-3 should be applied to the design of driveway throat For major traffic generators (greater than 5,000 trips per day), a traffic impact study analysis should be used to identify exit queuing conditions that may require additional throat length. ---PAGE BREAK--- City of Middleton, Wisconsin Access Management Plan Section 2–Access Management Prepared by Strand Associates, Inc.® 2-10 A B Residential/Commercial Driveways Speed to Left Restriction to Left to Right Restriction to Right A = Parking B = Parking 25 mph 30 mph 35 mph 40 mph 170 feet 205 feet 240 feet 275 feet 115 feet 140 feet 160 feet 180 feet Industrial Driveways 25 mph 30 mph 35 mph 40 mph 215 feet 255 feet 295 feet 340 feet 140 feet 165 feet 190 feet 220 feet 295 feet 355 feet 415 feet 475 feet Design ISD ISD 370 feet 445 feet 515 feet 590 feet Speed to Left Restriction to Left to Right Restriction to Right A = Parking B = Parking Design ISD ISD 370 feet 445 feet 515 feet 590 feet 445 feet 530 feet 620 feet 710 feet Figure 2.01-8 Driveway Vision Corners on Arterial Streets Source: Wisconsin DOT Facilities Development Manual 3. Driveway Curb Radii Curb radii design affects the turning radius used by vehicles entering a driveway and the speed of right-turning vehicles. Increased radii and vehicle speeds have a negative impact on pedestrian safety on adjacent sidewalks. Commercial/industrial driveway radii should range between 10 to 15 feet. This standard may require that larger trucks encroach on the exiting travel lane of the driveway when entering. In instances where the driveway radius is greater than the terrace width, the entrance will not be tangent to the driveway edge. 4. Driveway Vision Corners The final element of sound driveway design on arterial streets is the provision of adequate sight distance for entering and exiting vehicles. Vision corners shown in Figure 2.01-8 are defined by American Association of State Highway and Transportation Officials (AASHTO) based on the availability of gaps and speed of through traffic on the adjacent street system. The Intersection Sight Distances (ISD), shown in Figure 2.01-8, are those recommended by the Wisconsin Department of Transportation in its Facilities Development Manual. The recommendations for residential/commercial driveways are based on a passenger car design vehicle, while those for industrial driveways are based on a single-unit truck design vehicle. ---PAGE BREAK--- City of Middleton, Wisconsin Access Management Plan Section 2–Access Management Prepared by Strand Associates, Inc.® 2-11 The City of Middleton Public Works Committee decided that parking restrictions on collector streets will be considered on a case by case basis. Collector streets may either be subject to the restrictions shown in figure 2.01-8, or to State Statutes depending on the specific circumstances. Local streets will continue to be subject to State Statutes only.