Guide for the Analysis of Multimodal Corridor Access Management (2018)

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64 Description On-street parking is eliminated and off-street parking is substituted. Curbside stopping and loading activity occur off-street or during off-peak periods. Tables 45 and 46 follow. Quantitative Analysis Methods Motor Vehicle Operations Exhibit 18-11 in the HCM6 indicates that roadway free-flow speeds increase by 0.03 mph for each 1% reduction in the percentage of street length where on-street parking is allowed (2). Thus, eliminating on-street parking increases the free-flow speed by up to 3 mph and average travel speeds by a little less than the increase in the free-flow speed. In most cases, the speed increase will be lower, because right-turn lanes, driveways, and unsignalized intersections between traffic signals will reduce the street length where parking is not restricted and where parking is frequently restricted near driveways. Motor Vehicle Safety Table 13-50 in the HSM provides the following crash modification factors associated with prohibiting on-street parking (3). They are C H A P T E R 1 3 Parking and Stopping Restrictions Source: Photograph provided by the authors.

Parking and Stopping Restrictions 65 • Arterial (64-ft wide with 30,000 AADT): 0.58 (all crash severities), and • Arterial with 30,000–40,000 AADT: 0.78 (injury crashes), 0.72 (non-injury crashes). Pedestrian Operations Equations 18-32, 18-33, and 18-35 in the HCM6 (2) can determine the effect of prohibiting on-street parking on pedestrian link LOS. The removal of the barrier effect created by the parking reduces the pedestrian LOS score by 0.12–0.86 points, depending on how much parking was previously available and occupied, assuming 6-foot sidewalks, no landscape buffer, and standard lane widths. Increasing average traffic speeds by 2 mph worsens the pedestrian link LOS score by 0.03 points (at 20 mph) to 0.08 points (at 50 mph). The range covered by one LOS letter is 0.75 points. Bicycle Operations Equations 18-41, 18-42, and 18-44 in the HCM6 (2) can determine the effect of parking pro- hibitions on bicycle link LOS. The removal of the discomfort caused by riding between traffic Access Management Technique Performance Trends and Documented Performance Relationships Operations Safety Replace curb parking with off-street parking. ↑ ↓ ↑ ↑ ™ ↑ ↑ ↑ ™ ™ ˜ ˜ ˜ ˜ ˜ Implement curbside loading controls. ↑ ™ ↑ ↑ ™ ™ ™ ↑ ™ ™ ™ ™ ™ ™ ™™ Table 45. Multimodal operations and safety performance summary. Mode Operations Safety Motor vehicle free-flow and travel speeds increase by up to a few miles per hour, depending on the proportion of the street length where on- street parking was previously available (1, 2). Reduces the vehicular crash rate (3). Eliminating on-street parking will decrease pedestrian LOS, because parked cars serve as a barrier between traffic and pedestrians on the sidewalk and because motor vehicle speeds increase (2, 4). Improves the visibility of pedestrians for drivers turning into a driveway (1). Eliminating on-street parking substantially improves bicycle LOS (2, 4). This improvement is slightly offset by the small increase in motor vehicle speeds (2, 4). Eliminates the potential for “dooring” crashes. Improves the visibility for bicyclists crossing or who are about to cross a driveway (5). Improves interaction between bicycles and adjacent traffic (3). Similar to motor vehicles. Space previously used for parking can be repurposed as a curb extension at bus stops, providing space for passenger amenities and reducing bus delays leaving stops (but with potential impacts to motor vehicle and bicycle traffic) (6). No documented effect beyond that generally observed for motor vehicle and pedestrian traffic. No documented effect beyond that generally observed for motor vehicle traffic. No documented effect beyond that generally observed for motor vehicle traffic. Table 46. General trends associated with removing on-street parking.

66 Guide for the Analysis of Multimodal Corridor Access Management and a row of parked cars improves the bicycle LOS score by 0.38 to 2.00 points, depending on how much parking was previously available and occupied. In addition, the space previously used for parking becomes available for bicyclists to separate themselves from moving traffic and to maintain their line of travel (or can be explicitly striped as a bicycle lane), resulting in a greater improvement of the bicycle LOS score of 1.92 points, assuming an 8-foot parking lane. An increase in average traffic speed of 2 mph worsens the bicycle LOS score by 0.57 points (at 21 mph or less), 0.17 points (at 25 mph), 0.05 points (at 40 mph), and 0.03 points (at 50 mph). The range covered by one LOS letter is 0.75 points. Bicycle Safety Carter et al. (7) developed a model to predict a safety index for bicycle intersection; index values for all bicycle movements at an intersection improve by 0.2 rating points with the elimi- nation of on-street parking on the intersection approach. See the appendix for more details about this model. Additional Information • Chapter 15 in this guide. • Access Management Manual, Second ed.: Section 10.5.7. References 1. Texas Transportation Institute; Kittelson & Associates, Inc.; and Purdue University. Predicting the Performance of Automobile Traffic on Urban Streets. Final report. NCHRP Project 03-79. Transportation Research Board of the National Academies, Washington, D.C., Jan. 2008. 2. Highway Capacity Manual: A Guide for Multimodal Mobility Analysis, 6th ed. Transportation Research Board, Washington, D.C., 2016. 3. Highway Safety Manual, 1st ed. American Association of State Highway and Transportation Officials, Washington, D.C., 2010. 4. Dowling, R., D. Reinke, A. Flannery, P. Ryus, M. Vandehey, T. Petritsch, B. Landis, N. Rouphail, and J. Bonneson. NCHRP Report 616: Multimodal Level of Service Analysis for Urban Streets. Transportation Research Board of the National Academies, Washington, D.C., 2008. 5. Gattis, J. L., J. S. Gluck, J. M. Barlow, R. W. Eck, W. F. Hecker, and H. S. Levinson. NCHRP Report 659: Guide for the Geometric Design of Driveways. Transportation Research Board of the National Academies, Washington, D.C., 2010. 6. Ryus, P., K. Laustsen, K. Blume, S. B., and S. Langdon. TCRP Report 183: A Guidebook on Transit-Supportive Roadway Strategies. Transportation Research Board, Washington, D.C., 2016. 7. Carter, D. L., W. W. Hunter, C. V. Zegeer, J. R. Stewart, and H. F. Huang. Pedestrian and Bicyclist Intersection Safety Indices: Final Report. Report FHWA-HRT-06-125. Federal Highway Administration, Washington, D.C., Nov. 2006.