Traffic Safety
Review of Current Practices for Setting Posted Speed Limits: What are the 3 top highest percentages?
- 85th percentile operating speed - Crash frequency statistics - Surrounding land use (e.g. rural, fringe of city, fully developed)
Three most common collision factors:
- 95% Human - 28% Infrastructure - 8% Vehicle
What does success look like for the Zero Traffic Fatalities Task Force?
- Actionable and implementable recommendations on how to reduce traffic fatalities in California with the goal of Zero Fatalities. - Recommendations to be used as the basis for: • Policy • Design • Legislative action - Commitment and collaboration between agencies and stakeholders
Provide some other factors to be considered when setting speed limits.
- Adjacent land uses - Street widths and other road characteristics - Average daily traffic volume - Total number of fatal and injury crashes in a specified time period - Details of pedestrian, bike, and vehicle fatalities
Statewide Fatal & Serious Injury Collisions by Primary Cause:
- Alcohol or Drug Impaired - Improper Turning - Unsafe Speed - Automobile Right of Way - Pedestrian Violation - Traffic Signals and Signs - Wrong Side of Road - Pedestrian Right of Way - Unsafe Lane Change - Other than Driver (or Pedestrian) (2015-2019)
Be Safe and Be Seen: What are some ways to make yourself visible to drivers?
- Wear bright/light colored clothing and reflective materials. - Carry a flashlight when walking at night. - Cross the street in a well-lit area at night. - Stand clear of buses, hedges, parked cars, or other obstacles before crossing so drivers can see you. http://www.pedbikeinfo.org/resources/resources_details.cfm?id=5167
The Transit First policy was adopted by ...
- the San Francisco Board of Supervisors in 1973. It states that travel by foot, bicycle, and public transit are economically and environmentally sound alternatives to travel by private automobile. The policy encourages the use of public rights-of-way by people walking, riding bikes, or taking public transit and micromobility to meet public transportation needs. - Transit First is the directive to the SFMTA to design, build, operate, regulate and maintain the transportation network in San Francisco.
Chicanes
A chicane is a series of alternating mid-block curb extensions or islands that narrow the roadway and require vehicles to follow a curving, S-shaped path. Est. $8,000-$10,000
Roundabouts
A roundabout is a type of circular intersection that is different than a traffic circle. Traffic travels counterclockwise around center island and vehicles entering the roundabout must yield to enter. Est. $150,000- $2 million
Chokers
Chokers are types of curb extensions that narrow a street by widening the sidewalks or planting strips, effectively creating a pinch-point along the street. Est. $10,000- $25,000
Consider the use of automated speed enforcement (ASE) to compliment traditional enforcement -
Consider the use of automated speed enforcement (ASE) to compliment traditional enforcement - ASE is a proven tool to reduce speeding, injuries and fatalities. Cities in California require legislative authority to implement automated technology for enforcing traffic laws. This report summarizes policy considerations related to ASE, including enforcement location, notices, privacy, citation type, and use of revenue. ASE in San Francisco could complement traditional enforcement efforts to reduce dangerous driving and save more lives.
Engineering and Design Solutions: Barriers to Implementation:
Cost - Roadway infrastructure can range from $2,000 to $2 million depending on the design treatment. Long timeline - Implementing new roadway infrastructure can take years to plan, fund, design, and implement. Funding - Funding for infrastructure can be difficult to obtain and can be contingent upon certain criteria. Level of Service standards - Level of Service standards stipulate acceptable thresholds for traffic congestion and delay.
Curb Extensions
Curb extensions visually and physically narrow the roadway and increase the overall visibility of pedestrians by reducing the crossing distance for pedestrians. Est. $8,000-$12,000
Design:
Design: - Lane width reduction - Bike lanes - Parking - Road Diet - Raised Medians - Well-marked and planned intersections - Traffic calming devices • Chicanes • Speed humps - Modifying traffic signals and signs
Education:
Education: - No specifics given
Enforcement:
Enforcement: - Random enforcement periods - Automated speed enforcement (ASE) - Targeted and sustained enforcement
Engineering & Traffic Survey:
Engineering & Traffic Survey: - Defined by CVC 627 as a survey of "highway and traffic conditions in accordance with methods determined by the Department of Transportation for use by state and local authorities" and considers: • Prevailing speeds as determined by traffic engineering measurements • Traffic crash records • Highway, traffic, and roadside conditions not readily apparent to the driver. - 85th percentile speed of free flowing traffic is often considered a safe and reasonable speed limit.1 - Valid for five years, but may be extended to seven or ten years if a registered engineer determines conditions are met
Approaches to setting Speed Limits at the local, state, national, and international levels:
Engineering (or Operating) - A two-set process where a base speed limit is set according to the 85th percentile speed and adjusted slightly according to road and traffic conditions, crash history, and other factors. (United States) Safe System - Speed limits are set according to the crash types that are likely to occur, the impact forces that result, and the tolerance of the human body to withstand these forces. (Sweden, Netherlands, Australia) Expert System - Speed limits are set by a computer program that uses knowledge and inference procedures that simulate the judgement and behavior of speed limit experts. In the U.S., USLIMITS2 is a web-based expert speed zoning software advisor adapted from similar expert systems used in Australia. (United States, Australia) Engineering (or Road-Risk) - Speed limit is determined by the risks associated with the design of the road. The speed limit is based on the function of the road and/or the adjacent land use and then adjusted based on road and traffic conditions and crash history. (Canada, New Zealand) Optimization/Optimal - Setting speed limits to minimize the total societal costs of transport. Travel time, vehicle operating costs, road crashes, traffic noise, and air pollution are considered in the determination of optimal speed limits. Conceptual approach that has not been adopted by any road authority
NCUTCD Recommendations - Factors that should be considered:
Factors that should be considered: - Speed distribution of free-flowing vehicles (such as current 85th percentile, the pace, review of past speed studies). - Crash experience for at least a 12-month period relative to similar roadways. - Road characteristics (such as lane widths, curb/shoulder condition, grade, alignment, median type, sight distance). - Road context (such as roadside development and environment including number of driveways, land use, functional classification, parking practices, presence of sidewalks/bicycle facilities). - Road users (such as pedestrian activity, bicycle activity).
How does the state set speed limits to provide the best mobility for a safety constraint of zero traffic fatalities?
History of Setting Speed Limits in the US: - Speed limits are established by computing the 85th percentile speed during free-flow travel. - This approach was developed based on a 1964 USDOT report labeled "Accidents on Main Rural Highways Related to Speed". The report's findings have not been successfully replicated since. - Another stated rationale is that speed limits below the 85th percentile discourage drivers' compliance with the posted speed limit.
Be Smart and Alert: List some ways yo avoid dangerous behaviors.
- Always walk on the sidewalk. If there is no sidewalk, walk facing traffic. - Stay sober; walking while impaired increases your chance of being struck. - Don't assume vehicles will stop. Make eye contact with drivers, don't just look at the vehicle. - If a driver is on a cell phone, he or she may not be paying enough attention to drive safely. - Don't rely solely on pedestrian signals. Look before you cross the road. - Be alert to engine noise or backup lights on cars when in parking lots and near on-street parking spaces. http://www.pedbikeinfo.org/resources/resources_details.cfm?id=5167
Based on your knowledge and experience, where are speed limits allowed to deviate from the 85th percentile speed of traffic requirement?
- Business districts - Where conditions provide a basis for "engineering judgement" (e.g., collision history, pedestrian/bike safety, cross streets, etc.) • - Construction zones - Residence districts • - School zones - Senior zones - Hospital zones
Be Careful at Crossings: What are some best practices when looking before stepping?
- Cross streets at marked crosswalks or intersections, if possible. - Obey traffic signals such as WALK/DON'T WALK signs. - Look left, right, and left again before crossing a street. - Watch for turning vehicles. Make sure the driver sees you and will stop for you. - Look across ALL lanes you must cross and visually clear each lane before proceeding. Even if one motorist stops, do not presume drivers in other lanes can see you and will stop for you. - Don't wear headphones or talk on a cell phone while crossing. http://www.pedbikeinfo.org/resources/resources_details.cfm?id=5167
Based on your knowledge and experience, what existing policies effectively reduce speeds on local streets and roads?
- Design - Enforcement - Education
Provide some safety tips for drivers.
- Don't speed, follow the speed limit and never use your phone; always be cautious of your surroundings. - Never drive under the influence of alcohol and/or drugs. - Look out for pedestrians, especially in hard-to-see conditions such as at night or in bad weather. - Pedestrians have the right of way at any crosswalk or intersection, so yield and be prepared to stop. - Stop at the crosswalk stop line to give drivers in other lanes an opportunity to see and yield to pedestrians too. - Be cautious when backing up - pedestrians, especially young children, can move across your path. https://www.ots.ca.gov/media-and-research/campaigns/pedestrian-safety/
Limitations of ASE:
- Driver does not stop and may continue to speed. - Limited scope of enforcement and lack of direct contact with motorists. - Time lag between violation and penalty. - Challenged on several constitutional grounds, including: • Rights of due process • Rights of equal protection • Rights of privacy - Criticized by the public as a tool to generate revenue rather than increase safety.
5 Es OF TRAFFIC SAFETY:
- Engineering - Emerging Technology - Emergency Response - Education - Enforcement
Benefits of ASE:
- Frees up law enforcement resources to be used elsewhere and can serve as "force multiplier". - Can operate where: 1) in-person traffic stops would be dangerous; and 2) on higher speed roadways where traffic calming devices may not be appropriate. - May reduce congestion from other drivers distracted by traffic stops. - Ability to continuously enforce speed limit. - Proven to be an effective countermeasure to reduce speed related crashes and injuries.
2014-2019 SHSP Action Examples:
- Identify locations with reported pedestrian safety issues to conduct targeted, high-visibility pedestrian safety enforcement operations. The targeted locations will be continually monitored and updated as necessary. (OTS, CHP) - Conduct pedestrian safety presentations - in collaboration with schools, community groups, or local pedestrian advocacy groups - to promote pedestrian traffic safety awareness. (OTS, CHP) - Conduct analysis of local pedestrian crash data; disseminate to local health departments to inform pedestrian safety planning and programming. (CDPH)
2020-2024 Challenge Areas:
- Intersections - Driving Under the Influence - Speeding - Lane Departure - Driver Licensing - Pedestrians - Occupant Protection - Aging Drivers (>65) - Motorcycles - Young Drivers (<21) - Commercial Vehicles - Distracted Driving - Bicyclists - Work Zones - Emerging Technologies - Emergency Response
State's Zero Traffic Fatalities Task Force speed recommendations:
- Lower speeds on the High Injury Network - Lower speeds on streets near vulnerable populations, such as streets close to senior facilities, homeless shelters, parks or playgrounds, and healthcare facilities - Consider the use of automated speed enforcement (ASE) to compliment traditional enforcement
Based on your knowledge and experience, what are the alternatives to using the 85th percentile speed of traffic requirement?
- NACTO guidance - Safe System approach - Urban Speed Limit Study - Optimization approach - Amending speed and traffic surveys - Expert System approach - Complete Streets approach - Prima facie or de facto zones - Sensitivity to unique local conditions - Engineering approach - Larger deviation from 85th - Optimal speed limit percentile calculations - USLIMITS2 - Design-based criteria
High-Level Overview of ASE Process:
- Radar detects a speeding vehicle and triggers camera. - Camera captures identifying information (license plate and, if needed, driver. - Back-office processor processes violation and matches information to registration records. - Citation is mailed to vehicle owner or driver.
How does a capital need become an investment included in the CIP?
- SFMTA updates the Capital Improvement Program (CIP) every two years concurrently with the SFMTA Capital Budget. Capital needs must first be included in the twenty-year Capital Plan in order to be considered for funding in the fiscally-constrained five-year CIP. - The proposed Capital Budget and CIP undergoes a public outreach process comprising of a wide range of stakeholder groups. It is approved by the Transportation Capital Committee, an internal committee made up of representative from each SFMTA division and capital program, before being presented to the SFMTA Board. - The CIP is a dynamic document. As such, it is updated regularly and needs to shift or as fund availability changes. The Transportation Capital Committee meets monthly to review changes to scopes, schedules and budgets for existing CIP projects and to consider new projects as needs arise. The most up to date version of the CIP is maintained electronically and is available at sfmta.com
Factors most utilized in setting speed Limits?
- Speed of vehicles - Context-Location - Statutory Requirements
Effect of Bicycle and Pedestrian Plans on the 85th Percentile:
Increasing numbers of California cities and counties are creating bicycle and pedestrian transportation plans. These local planning documents, which are defined in the California Transportation Commission's Active Transportation Program Guidelines, as the first step to either initiate or continue with programs, policies, and projects that provide safe and efficient travel modes for bicyclists and pedestrians. In 2017, Caltrans released the first-ever statewide bicycle and pedestrian plan called Toward an Active California which outlines the policies and measures that the State and local governments can take to increase bicycling and walking. However, local government bicycle and pedestrian plans do not impact posted speed limits, which is primarily determined by the 85th percentile speed of motor vehicles. When calculating the 85th percentile speed of vehicles, there is no existing mandate to consider where future bicycle and pedestrian facilities are planned or in progress. However, if a city implements bicycle and pedestrian elements from its plan that changes roadway infrastructure, the project might affect the 85th percentile speed of vehicles. For instance, if a local jurisdiction implemented certain traffic calming interventions such as speed bumps, it could cause drivers to slow down which then impacts the 85th percentile speed of vehicles. Studies in Denmark and the United States have shown that the installation of a single speed bump reduced average speeds by 2.7 to 3.4 mph.
Advanced Driver Assistance Systems (ADAS)
Intelligent speed adaptation (ISA_ - ISA systems compare a vehicle's global position system (GPS) to the road's speed limit and either warn the driver or slow the vehicle in the case of excessive speed. Blind spot warning (BSW) - BSW systems detect vehicles traveling in the vehicle's blind spot and provide some form of warning to the driver. Automatic emergency braking (AEB) - AEB systems determine the distance between the vehicle and other vehicles/objects directly ahead and automatically apply brakes when it senses a crash is imminent. Many current-generation AEB systems are also designed to detect and respond to pedestrians and cyclists. Forward collision warning (FCW) - FCW systems determine the distance between the vehicle and other vehicles/objects directly ahead and warn the driver when the system determines an imminent threat. Many current-generation FCW systems are also designed to detect and respond to pedestrians and cyclists. Lane Departure Warning/Lane Keeping Assist (LDW/LKA) - LDW and LKA systems use cameras to determine the position of the vehicle in relation to lane markings. LDW systems are designed to prevent crashes in which the vehicle leaves its travel lane unintentionally.
What is the Muni Service Equity Policy?
It requires the SFMTA to prepare a Muni Service Equity Strategy to coincide with our two-year budget process. The second Muni Equity Strategy was adopted in April 2018 and evaluates transit service performance in select disadvantaged neighborhoods.
What is Daylighting?
It's a straightforward improvement that makes everyone on the street easier to see at intersections. It requires removing visual barriers within a minimum of 10 feet of a crosswalk or intersection.
Fundamental Concepts of The 85th Percentile Methodology:
Key Concepts: - The majority of drivers will naturally drive at safe, reasonable speeds. - Speed limits are safest when they conform to the speed driven by most drivers. - The norms of a reasonable person should be considered legal. - Uniform vehicle speeds increase safety and reduce the risks for crashes.
Lower speeds on streets near vulnerable populations, such as -
Lower speeds on streets near vulnerable populations, such as streets close to senior facilities, homeless shelters, parks or playgrounds, and healthcare facilities - In San Francisco, some communities and road users are disproportionately impacted by traffic deaths, such as seniors and people experiencing homelessness. Greater flexibility to reduce speeds on streets near vulnerable populations allows San Francisco to elevate equity in working to save lives.
Lower speeds on the High Injury Network:
Lower speeds on the High Injury Network - San Francisco's High Injury Network (HIN) represents the 13% of streets where 75% of severe and fatal injuries occur. Greater flexibility for setting speeds on the High Injury Network would allow San Francisco to reduce speeds on streets with the highest proportion of severe and fatal injuries.
Major Limitations of The 85th Percentile Methodology:
Major Limitations: - Not supported by scientific research - Privileges driver behavior - Based on a set of historical assumptions - Does not require consideration of other road users such as pedestrians and bicyclists - Same methodology applied to different roadway types - Assumes drivers will choose reasonable and prudent speeds - Can lead to speed creep
Speed Limits - Special Conditions:
Speed Limits - Special Conditions: - School Zone local authorities can reduce the maximum speed limit allowable to 25 mph, or lower if the E&TS indicates that 25 mph is too fast for prudent and safe operations1 - Work Zone authorized to "restrict the use and regulate the movement of traffic"2 and can be set as low as 25 mph3 - Other 15 mph in alleys, at blind intersections, blind railroad xing, and more4 - Variable displayed on CMS due to specific conditions such as weather, congestion, and more.
Provide some safety tips for pedestrians.
Make yourself visible: wear bright colored clothes and carry a flashlight if you are walking at night. Avoid dangerous behaviors: always walk on the sidewalk (no jaywalking), stay sober and make eye contact with drivers - don't assume the driver can see you. Stay off your phones, talking and especially texting distracts you from paying attention to your surroundings. - Look before you step: cross streets at marked crosswalks/intersections, obey traffic signals and watch for turning vehicles. - Look left-right-left before crossing a street. https://www.ots.ca.gov/media-and-research/campaigns/pedestrian-safety/
Median Islands
Median refuge islands are protected spaces placed in the center of the street to facilitate bicycle and pedestrian crossings. Est. $15,000- $55,000
Micromobility
Micromobility refers to a range of small, lightweight devices operating at speeds typically below 25 km/h and is ideal for trips up to 10km. Micromobility devices include bicycles, Ebikes, electric scooters, electric skateboards, shared bicycles, and electric pedal assisted bicycles.
NTSB Safety Study Recommended:
NTSB Safety Study Recommended: - (H-17-27) Revise Section 2B.13 of the MUTCD: • Factors currently listed as optional for all engineering studies are required • Require that an expert system such as USLIMITS2 be used as a validation tool • Remove the guidance that speed limits in speed zones be within 5 mph of the 85th percentile speed. - (H-17-28) Revise Section 2B.13 of the MUTCD: • to (at a minimum) incorporate the safe system approach for urban roads to strengthen protection for vulnerable road users.
Limitations of the 85th Percentile for Local Streets in Urban Settings:
On local streets in urban environments, speed creep is also a limitation associated with the 85th percentile approach. Studies have demonstrated that "spatial" speed creep on local roads can be caused by high speeds on connecting highways. Higher speed limits on highways can thus have a "carry-over" effect on local roads. Additionally, many limitations of the 85th percentile approach specific to local streets are behavioral. These behavioral limitations expose the difficulties associated with basing speed limits on driver's habits. Driver behavior lies at the root of the 85th percentile methodology, which assumes that most drivers will naturally choose to drive at a safe and reasonable speed. Yet UC ITS researchers contend that drivers tend to underestimate their speed by 10-30% and that drivers have "limited capacity" to choose a safe speed. When drivers exceed the posted speed limit, one of the key reasons is their belief that excess speed does not threaten safety. Additionally, poor weather conditions and the lack of strong visual cues on local roads (such as guardrails or trees) can further cause drivers to underestimate their speeds. These research results indicate that drivers are not good at "naturally" selecting safe speeds and suggests that it is not prudent to use driving habits as a basis for establishing speed limits. Ultimately, "the conjecture that safe speed limits should be determined based on the actual driving habits of drivers cannot be used to establish safe travel speeds on local streets."
Limitations of the 85th Percentile for Highways in Rural Settings:
One of the primary limitations of using the 85th percentile in rural highway settings is the cyclical phenomenon of speed creep. As recent research has indicated, raising speed limits to match the 85th percentile speed of vehicles leads to higher operating speeds, which can then contribute to a higher 85th percentile speed. Research has shown that over time, vehicle operating speeds continue to increase even if the road and vehicle conditions remain the same, demonstrating that the posted speed limit has the most impact on a driver's travel speed.
Transit First Investments
Over the next five years, the SFMTA will continue to roll out an unprecedented investment in transit infrastructure and service improvements, including: • Continuing to implement the Rapid Network serving nearly 70% of all riders to provide more frequent and reliable service • Making the transit system smarter and more reliable by investing in new technology, improving integration between traffic signals and transit, and improving real-time transit information • Update and expand our transit fleet to expand service capacity and improve the safety, comfort, and reliability • Integrate Complete Streets projects with the needs of families, seniors, and the disabled while reviewing them to support the City's Vision Zero goals.
Goal of the transportation system?
Provide mobility. Provide efficient, cost-effective, equitable, sustainable, ..., and safe mobility. https://calsta.ca.gov/-/media/calsta-media/documents/safetrec_grembek_ab2363_06252019-a11y.pdf
Raised Crosswalks
Raised crosswalks bring the level of the roadway to that of the sidewalk, forcing vehicles to slow before passing over the crosswalk and providing a level pedestrian path of travel from curb to curb. Est. $4,000-$8,000
Speed humps/speed table
Speed humps and speed tables are devices that encourage people driving to slow down. Speed humps and tables are raised areas that extend across the street. A speed hump is rounded whereas a speed table has a flat top to accommodate a car's entire base. Speed hump: Est. $2,000-$4,000 Speed table: Est. $2,500-$8,000
Common Types of Speed Limits:
Statutory - speed limits are established by the State legislature. They are enforceable by law even if the speed limit sign is not posted. Prima Facie - speed limits are a type of statutory speed limit that apply in designated special areas or zones, including school zones, business districts, and residential areas. They are enforceable by law even if the speed limit sign is not posted. Posted - speed limits can be the same as Statutory speed limits, or they can be different limits established by a local authority on the basis of an engineering and traffic survey. They must be posted in order to be enforceable. Absolute - speed limits are statutory speed limits. They designate an upper limit beyond which any speed is illegal.
Statutory and Posted Speed Limits:
Statutory and Posted Speed Limits: - Statutory speed limit (maximum speed limit) • Set by the State Legislature and enforceable even if speed limit sign is not posted - Posted speed limit (regulatory speed) • Set by a local jurisdiction (city or county) • Must have an up-to-date Engineering and Traffic Survey to be enforceable when radar or LiDAR is used • Takes priority over the established statutory speed limit
Using the 85th Percentile in Urban and Rural Settings:
The 85th percentile methodology was established based on research primarily conducted on rural roads. Rural roads are generally long stretches of uninterrupted roadway, while urban areas are generally characterized by frequent interactions between cars and vulnerable users of the roadway, including pedestrians and bicyclists. Calculating the 85th percentile speed via engineering and traffic surveys is the same regardless of roadway type. Given the differences between urban and rural settings, applying the same me
What is the California State agency specializing in media and research for those looking for grants in traffic safety?
The California Office of Traffic Safety's (OTS) mission is to effectively and efficiently administer traffic safety grants while fostering partnerships to deliver innovative programs that reduce traffic deaths, injuries and economic losses. https://www.ots.ca.gov/
What's the basic parameter in the design of a safe transport system?
The kinetic energy that the human body can tolerate, forms the basic parameter in the design of a safe transport system.
Traffic Circles
Traffic circles guide vehicles through an intersection in one direction around a central island. They are usually installed at intersections of neighborhood streets. Est. $10,000- $25,000
Types of Speed Limits:
Types of Speed Limits: - Basic Speed Law (CVC 22350) states that a driver may never driver faster than is reasonable or prudent for current conditions. - Two types of speed limits • Statutory speed limit • Posted speed limit
What is the most important regulator factor for safe road traffic?
Vehicle speed is the most important regulating factor for safe road traffic since it is subject to road-user behavior.
What is Vision Zero?
Vision Zero is San Francisco's initiative to eliminate traffic fatalities and reduce severe traffic-related injury on San Francisco's streets. A standardized case definition of traffic fatality across city agencies ensures consistency, and is critical for data collection, analysis and evaluation of the burden of traffic mortality in the City and County of San Francisco, as well as tracking progress towards Vision Zero.
The Vision Zero SF initiative is spearheaded by ...
a city Vision Zero task force which is chaired by the SFMTA and SF Department of Public Health with support from important partner agencies such as the SF Police Department and SF Public Works.
