Loading...
HomeMy WebLinkAbout2024-02-05; Traffic Safety and Mobility Commission; ; Complete Streets Best Practices: New Bikeway Treatments and Roadway WidthsMeeting Date: Feb. 5, 2024 To: Traffic Safety & Mobility Commission Staff Contact: Nathan Schmidt, Transportation Planning and Mobility Manager Subject: Nathan.Schmidt@carlsbadca.gov or 442-339-2734 Tom Frank, Transportation Director/City Engineer Tom.Frank@carlsbadca.gov or 442-339-2766 Complete Streets Best Practices: New Bikeway Treatments and Roadway Widths Recommended Action Receive an informational presentation on Complete Streets Best Practices including an overview of recent street striping such as bike lane treatments and roadway travel lane widths. Executive Summary The purpose of this informational report is to provide the Traffic Safety & Mobility Commission with an overview and description of benefits of the new roadway striping improvements that have been implemented as part of the city’s traffic safety enhancements. This report will explain how staff determines appropriate vehicle travel lane widths and how this provides a benefit to all roadway users. This report can also assist the commission in evaluating proposed street design projects in the city. Discussion The Transportation Department is working on dozens of projects and initiatives designed to align city streets with the policies of the city’s General Plan. The General Plan reflects changes in state law requiring cities to take a “complete streets” approach to road design. Complete streets are designed to accommodate all of the different ways people might want to get around the city. By making streets more accessible for walking and biking, complete streets support other goals such as reducing greenhouse gases, reducing vehicle traffic, supporting healthy lifestyles and creating a stronger sense of community. The General Plan recognizes that one size does not fit all when it comes to transportation. The plan puts city streets into different categories, each with its own set of operational priorities. For example, streets most conducive to walking and biking, such as those in the Village and along the coast, prioritize wider bike lanes and sidewalks. Main thoroughfares, such as El Camino Real, prioritize car traffic with multiple lanes. The city’s work of transforming local streets was already well underway when, on Aug. 23, 2022, the city proclaimed a local traffic safety emergency. The main safety focus of the emergency was related to bikes including electric bikes or e-bikes; however, the city’s approach focused on encouraging safe behaviors among all road users. In response to the local emergency, the City Council approved a Feb. 5, 2024 Item #3 Page 1 of 9 comprehensive approach to traffic safety. This approach, summarized in the Safer Streets Together Plan, included adding new street redesign projects and moving up the timing of others. One of the projects prioritized by the Safer Streets Together Plan is the resurfacing and restriping of Carlsbad’s major east-west corridors. This project, which is currently in construction, incorporates complete streets strategies in an effort to help reduce vehicle speeds and increase safety. Reducing speeding through street design The implementation of complete streets designs, which aim to enhance safety and provide more accessible to all users including bicyclists, pedestrians, and motorists, requires a careful analysis of vehicle travel lane widths. An important element of the recent restriping project is the placement of appropriate vehicle lane widths. Appropriate sizing of vehicle lanes is crucial in this context for several reasons: • Speeding is listed as the number one cause of injury collisions in Carlsbad, cited as the “primary collision factor” in 25% of these crashes. Distracted driving is often associated with this collision factor as well. • Properly designed lanes encourages drivers to pay more attention and drive appropriate speeds. • Lane width is based on several factors, including traffic volume, speed, the type of street and its location. • Compliance with national industry practices and recommendations. A new report from researchers at the John Hopkins Bloomberg School of Public Health further highlights the critical role street design and lane widths play in traffic and pedestrian safety. The study includes analysis of 1,117 streets in seven U.S. cities found that even slightly narrower lane widths are, in many cases, safer than wide travel lanes. The study found that the number of vehicle collisions do not significantly change in streets with a lane width of nine feet compared to streets with lane widths of 10 feet or 11 feet. There are significant increases in collisions, approximately 1.5 times higher, when the lane width increases from Feb. 5, 2024 Item #3 Page 2 of 9 nine feet to 12 feet. A summary of this report is provided in Exhibit 1 and the full study can be found at the following website: https://narrowlanes.americanhealth.jhu.edu/ In conclusion, the relationship between vehicle travel lane widths and the implementation of complete streets designs is a pivotal aspect of urban planning that requires a balanced approach. The goal is to ensure that streets are safe, functional, and welcoming for all users, fostering a more sustainable and inclusive urban mobility framework. New bikeway design features Many of the city’s bike lanes are being enhanced by widening and adding buffers and green paint to highlight critical conflict zones between bicyclists and vehicles. Buffered Class-II bike lanes When roads are restriped, there is often an opportunity to create a buffer between cars and bikes. Buffered bike lanes are conventional (Class-II) bicycle lanes with a designated buffer space separating the bicycle lane from the adjacent motor vehicle travel lane and/or parking lane. The California Manual on Uniform Traffic Control Devices, or CA MUTCD, serves as the state’s guidelines for traffic control devices including striping. Buffered bike lanes are included in the CA MUTCD. In addition to the guidelines found in the CA MUTCD, the city’s current standard of practice specify a minimum buffer width of two feet. The minimum bike lane width with buffer is six feet. If the total width for bike lane/buffer is between six feet and eight feet, no buffer is to be provided. Buffered Class-II Bike Lanes Through bike lanes with conflict zone striping For bicyclists traveling in a bike lane, the approach to an intersection with vehicular turn lanes can present a significant challenge. For this reason, it is important that bicyclists are provided with an opportunity to correctly position themselves to avoid conflicts with turning vehicles. Ideally, bicyclists should be able to travel straight through the conflict zone area of the intersection while right turning vehicles are required to transition into the right turn pocket. This allows for the greatest visibility of Feb. 5, 2024 Item #3 Page 3 of 9 bicyclists at the critical conflict zone area. The following outlines the numerous safety benefits of bike lane conflict zone treatments: • Enables bicyclists to correctly position themselves to the left of right turn lanes or to the right of left turn lanes. • Reduces conflicts between turning motorists and bicycle through traffic. • Provides bicyclists with guidance to follow the preferred travel path. • Leads to more predictable bicyclist and motorist travel movements. • Alerts motorists to expect and yield to merging bicycle traffic. • Signifies an appropriate location for motorists to safely merge across the bike lane into the turn lane. Combined bike lane / right turn lane with green dashed striping To avoid conflicts between bikes and right-turning vehicles, bike lanes are placed on the left hand side of any right turn lane. These bike lanes are enhanced in green paint to highlight the presence of bicyclists in between vehicle lanes. Dashed green is used to highlight the area where motorists are encouraged to cross the bike lane and into the right turn lane. These new markings are there to remind road users to watch for bicyclists or be alert for potential conflict zones. For example, in the graphic below you see the conflict zone highlighted with dashed green markings within the right turn. The green paint does not change the rules of the road. The green is there to alert vehicles to the potential presence of bicyclists within the bike lane at the intersection. Feb. 5, 2024 Item #3 Page 4 of 9 Bike lane conflict zone with sharrows (mixing zones) In situations where a through lane transitions into a right turn only lane, a continuous bike lane is not possible. Therefore, a “mixing zone” will be established using shared lane markings (sharrows). Mixing zones help position vehicles closer to the curbside to help facilitate the right turn and reduce right hooks with bicyclists. The example shown below includes a greenback sharrow that indicates that multiple transportation modes may “mix” in this area. Feb. 5, 2024 Item #3 Page 5 of 9 Solid green paint at curves Solid green paint can also be used on curves to highlight the presences of bike lanes at curves where bicyclists may be less visible and to discourage vehicles from encroaching into the bike lane. Door zone striping Door zone striping establishes a buffer between the bike lane and parked vehicles using a dashed line. This line helps keep bikes out of the door zone and alerts bikes to watch out for people opening doors in parked cars. Feb. 5, 2024 Item #3 Page 6 of 9 Fiscal Analysis This item is a presentation on the work related to management of the city’s transportation assets and, as such, there is no financial impact related to this item. Environmental Evaluation (CEQA) Pursuant to Public Resources Code Section 21065, receiving a presentation on the work of the Public Works Branch, Transportation Department does not constitute a “project” within the meaning of the California Environmental Quality Act, or CEQA, in that it has no potential to cause either a direct physical change in the environment, or a reasonably foreseeable indirect physical change in the environment. Public Notification This item was noticed in accordance with the Ralph M. Brown Act and was available for public viewing and review at least 72 hours prior to the scheduled meeting date. Exhibit 1. Narrowing Travel Lanes Saves Lives: A summary of the findings of narrowing travel lanes from Hopkins Bloomberg School of Public Health Feb. 5, 2024 Item #3 Page 7 of 9 NARROWING TRAVEL LANES SAVES LIVES With rising pedestrian and cyclist fatalities, U.S. cities need cost-effective ways to improve safety within existing roadways. There’s a solution hiding in plain sight. KEY INSIGHTS 9, 10 and 11 ft. lanes did not increase accident risk or frequency, compared to 12-ft. lanes. Wider lanes at faster speeds had significantly more crashes than narrower lanes, but slower speeds had no difference. Narrower lanes help the environment by allowing more users in less space and using less pavement. Narrowing lanes offers great opportunities for adding bike lanes and wider sidewalks to existing streets without compromising safety. 35 MPH REDUCED CRASHES NARROWER LANES — 9’ 1 2 3 4 →40% increase in pedestrian fatalities and 44% increase in cyclist fatalities from 2010 to 2018. →16% increase in the number of deadly car accidents in the U.S. between 2018-2022. →About 8% of streets in New York City have a dedicated bike lane, despite being one of the most bike-friendly cities in the U.S. A national study of 1,117 streets in seven U.S. cities evaluated how travel lane widths impact traffic safety. The findings? Wider lanes are not necessarily safer. In fact, narrowing travel lanes can improve safety, optimize sidewalks and bike lanes, reduce environmental impacts and boost economic activity. Exhibit 1 Feb. 5, 2024 Item #3 Page 8 of 9 HOW DEPARTMENTS OF TRANSPORTATION ACROSS 5 STATES ARE IMPROVING ROAD SAFETY →Florida: FDOT uses a context classification system, allowing designers to choose the best design based on the area’s needs. →Vermont: VTrans was the first state to change the minimum lane width to 9 feet in urban areas. →Oregon: ODOT uses design criteria vs. standards for more flexibility in decisions about lane width and street design. →California: Caltrans uses a “complete streets” approach, considering the needs and safety of all users to determine street design. →Delaware: DelDOT rarely uses less than 11-ft. lanes, due to higher speeds and more transit vehicles. RECOMMENDATIONS Take a holistic approach to street design by considering the needs of all users, over speed and traffic efficiency. Start with 10-ft. lanes in slower speed urban areas and let engineers justify wider widths. Establish a context-appropriate speed before determining lane width. Launch a lane repurposing program to add a bike lane or wider sidewalk. The best roads for travel lane reduction projects are 11-13-ft. lanes in urban areas with slower speeds and streets with less traffic, limited street parking, fewer lanes, low degrees of curvature, and no raised medians. 1 3 2 4 This project was led by Dr. Shima Hamidi, Ph.D., Bloomberg Assistant Professor of American Health and director of the Center for Climate-Smart Transportation with funding from the Bloomberg American Health Initiative. “HERE ON THE EAST COAST OUR ROADWAY CORRIDORS ARE REALLY TIGHT. IF WE CAN NARROW OUR ROADWAYS IN DELAWARE TO ACCOMMODATE MORE CYCLISTS AND PEDESTRIANS IT WILL MAKE A HUGE DIFFERENCE.” Mike Simmons Chief of Project Development South, Delaware Department of Transportation Ready to get started? For more information and to read the full report, visit narrowlanes.americanhealth.jhu.edu Feb. 5, 2024 Item #3 Page 9 of 9 Complete Street Best Practices: New Bikeway Treatments and Roadway Widths Tom Frank, Transportation Director/City Engineer Nathan Schmidt, Transportation Planning and Mobility Manager Feb. 5, 2024 RECOMMENDED ACTION •Receive an informational presentation on Complete Streets Best Practices including an overview of recent street striping such as bike lane treatments and roadway travel lane widths. ITEM 3: STREET STRIPING EXPLAINED 2 SAFER STREETS TOGETHER PRIMARY COLLISION FACTORS 5 ITEM 3: STREET STRIPING EXPLAINED RESTRIPING APPROACH •Vehicle Lanes: 10-11 ft. wide •Bike Lanes: •8-ft. wide bike lanes (6-ft. minimum) •3-ft buffers next to vehicle lanes and door-zones •Green paint reserved for conflict zones •Transitions to existing striping configurations at interchanges (within Caltrans right-of-way) ITEM 3: STREET STRIPING EXPLAINED TRAVEL LANE WIDTHS •Traditional guidelines suggest wider lanes (11–13 feet) are preferred for vehicle capacity benefits, but new research challenges these assumptions. •Narrower lanes (10-11 feet): •Promote slower speeds •Reduce crash severity •Multimodal safety benefits: Allows more space for pedestrians and bicyclists ITEM 3: STREET STRIPING EXPLAINED RECENT STUDY ON LANE WIDTHS •Based on a sample of 1,117 street sections from seven different cities in the U.S. •Key Finding: Narrower lanes did not increase risk of crashes in comparison to 12 ft. or wider travel lanes •Wide travel lanes produce greater speeds and drivers drive more carelessly when they have more room to make mistakes •Speed plays a critical role in the safety of all roadway users ITEM 3: STREET STRIPING EXPLAINED CARLSBAD LANE WIDTH DATA •Carlsbad Village Dr west of I-5: •Lanes narrowed to 9.5 ft. in 2011 •Sideswipe collisions did not increase in the four years after lane narrowing compared to four years prior •Other areas with lane width reductions: Cannon Rd., Poinsettia Ln, College Blvd.; no current data supports increase in sideswipe collisions •Staff will continue to monitor collision data after implementation of projects and adjust as needed ITEM 3: STREET STRIPING EXPLAINED 11 12 13 15 DOOR ZONE STRIPING NEXT STEPS •Conduct “Before and After Studies”: Speed surveys and traffic counts to evaluate performance of recent restriping and lane narrowing projects •Continual monitoring of collision data for trends •Ongoing implementation of the pavement management program ITEM 3: STREET STRIPING EXPLAINED 17 RECOMMENDED ACTION •Receive an informational presentation on Complete Streets Best Practices including an overview of recent street striping such as bike lane treatments and roadway travel lane widths. ITEM 3: STREET STRIPING EXPLAINED 18 1 February 2, 2024 Re: 2/5/2024 Agenda Items 1 and 3 (lane narrowing) Carlsbad Traffic Safety & Mobility Commissioners and staff: I submitted a similar version of this communication on 1/7/2024 to council and your commission, but I guess it was not distributed to the commission for some unknown reason. I have raised some of these issues in the past, but please refer to the new source documents and links I have provided. QUESTIONS FOR THE COMMISSIONERS TO ASK STAFF While lane-narrowing may increase safety on some lower-speed, lower-volume streets with few large vehicles, staff's extrapolation of this approach to our high-speed, high-volume suburban arterials is misguided, unsupported by evidence or standards, and potentially dangerous. Here are two simple questions for staff, which they can just answer during their presentation, or, if not, you should ask during questioning. They are based on the two standards (state and federal) that staff has cited as supporting their lane narrowing projects: 1. How are 10 or 10.5 feet wide lanes consistent with the Caltrans Highway Design Manual standard (the state standard cited by staff), which clearly says in Sections 301 and 308 that minimum lane width is generally 12 feet or (under limited circumstances) 11 feet? Requesting a special exception from Caltrans to go lower than these standards is not a way of meeting them. 2. How are 10 or 10.5 feet wide lanes on our 35 to 55 mph arterial streets consistent with the AASHTO Green Book standard (the federal standard cited by staff), which clearly says in the arterial streets section (7.3.3.2) that through-lanes less than 11 feet should be restricted to arterials with speeds less than 35 mph? THROUGH-LANE WIDTHS The consensus among the design standard-setting organizations, researchers, and other experts is that great caution needs to be exercised when narrowing lanes, and that arterial lane widths less than 11 feet should be restricted to streets with speeds of 30 to 35 mph or less with lower total volumes of vehicles and few large vehicles (buses, trucks). Inconsistent with these standards, staff’s lane narrowing projects are being done on many streets with speeds of 40 to 55 mph--some of which carry high volumes and/or are truck/bus routes. In their staff report, staff cites the largest-ever nationwide study on narrowed lanes, published last year by Hamidi et al.—strong proponents of the practice. However, the authors of this very report cited by staff specifically recommend lanes less than 11 feet only on streets with speeds of 35 mph or less. In addition, former ITE President Randy McCourt issued a strong warning about the safety hazards of lane narrowing in an accompanying NPR interview about this study: "It's a slam dunk on the 20 and 25 [mph streets], but when you get to the 35, 40, you got to be very careful." 2 Thus, staff's extrapolation of these results to the 40 to 55 mph through-lanes on our high-volume arterials lacks good engineering judgement and is potentially dangerous. Staff claims that they have analyzed the conditions on all of the streets on which lanes are being narrowed and determined that there are no safety concerns. However, in response to my public records request for specific safety analyses on each street, none existed. Instead, staff has only made the generic claim that all of the projects are allegedly consistent with the lane widths in the following national and state standards. AASHTO “Green Book” (national standard) Staff cites an introductory sentence in Section 4.3 of the Green Book (the first highlighted sentence below) that describes the fact that city street lane widths are generally between 9 and 12 feet, and they state that their 10-foot lanes are within that range. However, this is extremely deceptive, because that same paragraph goes on to explain how Chapters 5 through 8 need to be used for guidance on specific street types (the second highlighted sentence below): Moving on to the relevant guidance on arterial streets, Chapter 7 of the Green Book indicates that 12-foot through-lanes are desirable on high-speed, free-flowing principal arterials, while narrower 11- foot lanes are normally adequate for 45-mph or less arterials, but 10-foot lanes are only appropriate on arterials with speeds less than 35 mph and few large vehicles (buses, trucks): 3 Caltrans “Highway Design Manual” Sections 301 and 308 (state standard) In Carlsbad, Caltrans generally only regulates the portions of the city's streets at the highway interchanges, while they more broadly regulate city streets in unincorporated areas. In any event, the references to lane widths in the manual requires 12 feet in most circumstances, with an absolute minimum of 11 feet under certain conditions when speeds are 40 mph or less. In fact, Carlsbad staff has been forced to seek special exceptions from Caltrans outside of Caltrans standards to allow lane widths less than 11 feet at the interchanges. Thus, staff’s citation of this standard to justify widths of 10 or 10.5 feet is mystifying. Read it for yourself in the linked documents. Although not cited by staff, one of the most comprehensive and modern “complete streets” design standards is ITE’s “Designing Walkable Urban Thoroughfares.” Similar to the Green Book, it emphasizes street context and restricts the narrowing of arterial lanes to less than 11 feet to streets with speeds less than 35 mph. Read it for yourself in the linked document. SPEEDS AFTER NARROWING Some small studies suggest that lane narrowing might reduce speeds by a few mph on some street types (e.g., NCHRP Project 03-72). However, results are very mixed, and more robust, nationwide studies have concluded that lane widths have little or no effect on speeds on high-speed suburban arterials, (e.g., NCHRP Project 17-53). Due to the much larger sample sizes and wider geographic distribution, the latter results are considered more credible by the Transportation Research Board (NHCRP Report 783). Even if one assumes that narrowed lanes can reduce arterial speeds by a few mph, I am unaware of any published evidence directly linking that to better injury outcomes—it is all assumptions layered upon other assumptions. The lack of any meaningful change in speeds is instead coupled with increases in lane encroachments and sideswipes that can make things more dangerous for all users, including cyclists (Dai et al., 2020). NARROWED CENTER TURN LANES The Caltrans Highway Design Manual and the Texas Department of Transportation indicate that the preferred width of two-way left-turn lanes (TWLTLs) is 14 feet, and that the minimum width must be 12 feet, with exceptions down to 11 feet on very low-speed urban streets. Iowa also includes a preferred width of 14 feet and an absolute minimum of 12 feet. However, many of these narrowing projects now also include striping TWLTLs down to 10 feet, which is further exacerbated by the fact that they are often sandwiched between two 10-foot through-lanes going in opposite directions. The mirrors on larger vehicles span 10-1/2 feet. Can you imagine entering a 10-foot wide TWLTL with cars traveling at significant speeds on either side of you? Best regards, Steve Linke (splinke@gmail.com) Carlsbad Item 3 (Roadway Widths) Steve Linke 2/5/2024 Carlsbad traffic commission meeting Johns Hopkins study Johns Hopkins Study •All intersection collisions were excluded from their results ITE President on Hopkins study Lane widths Designing Walkable Urban Thoroughfares •Recommended Practices –[O]n the lower-speed urban thoroughfares…(target speeds of 35 mph or less), a range of lane widths from 10 to 12 feet on arterials and 10 to 11 feet on collectors is appropriate. On arterials with target speeds below 30 mph, widths in the lower end of the range are appropriate (10 to 11 feet).On collectors with a target speed below 30 mph, a 10-foot lane width may be appropriate unless [other] design considerations or other factors warrant a wider lane. –[V]ehicles such as transit buses or large tractor-trailers require wider lanes, particularly in combination with higher design speeds if they frequently use the thoroughfare. Modern buses can be 10.5 feet wide from mirror to mirror and require a minimum 11-foot wide lane on roadways with 30 to 35 mph target speeds. TRB/AASHTO/FHWA NCHRP Report 783 on the effects of lane width on speed •Recent research by Potts et al…found that mean speeds at sites with wider lanes (ranging from 11.9 to 13.3 ft) were approximately 4 mph higher than mean speeds at sites with narrower lanes (ranging from 9.4 to 10.3 ft in width). This finding suggested that lane width has an effect on traffic operations. However, the sample size in the study was relatively small (five pairs of wide-and narrow-lane sites) and was not sufficient to develop a formal relationship between lane width and traffic speed. •A similar evaluation in the NCHRP Project 17-53 research considered a total of 23 additional sites on urban and suburban arterials in the Eastern, Midwest, and Western regions of the United States (see Section 4.1). This evaluation found that lane width had no effect on traffic speeds on urban and suburban arterials. Based on this finding…lane width has no effect on traffic speeds on urban and suburban arterials... Questions for staff (again) •How are 10 or 10.5 feet wide lanes consistent with the Caltrans Highway Design Manual standard Section 308? •How are 10 or 10.5 feet wide lanes on our 35 to 55 mph arterial streets consistent with the AASHTO Green Book standard?