Test 2 Prep Flashcards
What are the 7 parts of a roundabout?
Central island, splitter island, circulatory roadway, apron, entrance line, accessible pedestrian crossings, landscape strip
What is a central island?
A raised area in the center around which traffic circulates (not necessarily circular, can be traversable)
Splitter island
Raised/painted area on approach used to separate entering/exiting traffic - Deflect to slow entering traffic, 2-stage pedestrian crossing
Circulatory roadway
Curved path used by vehicle to travel counterclockwise around the central island
Apron
Traversable portion of the central island adjacent to circulatory roadway needed for wheel tracking of large vehicles
Entrance line
Point of entry into circulatory roadway- Extension of circulatory roadway edge line, functions as a yield
Accessible pedestrian crossings
Crossing location typically set back from entrance line splitter island typically cut to allow pedestrians (including wheelchairs) to pass through
Landscape strip
Separate vehicular and pedestrian traffic
Difference between roundabouts, rotaries, and traffic circles
Rotaries are older, higher speeds on approaches, can require circulating traffic to yield to entering traffic
How do costs differ from signalized intersections?
Roundabouts are not signalized, have lower life cycle costs, and promote increased fuel efficiency
How do roundabouts accommodate pedestrians and cyclists?
Pedestrians are safer because of reduced speeds of entering vehicles, shortened ped. crossings, bicyclists can use crossings or ride through roundabouts
How do roundabouts accommodate trucks?
Can be built to accommodate large turning radii of large trucks and trailers, can be safer and more efficient in emergency situations
Downsides to roundabouts
Sometimes do not properly accommodate cyclists, issues with multilane circulating roadways
Dutch solutions for roundabout issues
Cycle track around roundabouts, turbo-roundabouts
What is a turbo-roundabout?
Multilane design, discourages lane changing on approach, cyclists and peds given priority, small circles and wide entrances force low speeds from motorists, single lane for entry and exit
Curbside productivity index
Takes into account vehicle activity, occupancy size, and dwell time to provide relative utility of a given curb space
Level of Traffic Stress
4 different ratings of comfortability of bike environments - most stressful aspect governs the chosen rating
Risk exposure model
Number of incidents equals risk times exposure
Risk
Probability of crash per exposure
Exposure
Opportunity for interaction with hazard
Vision Zero
Campaign to help communities to eliminate all traffic fatalities and severe injuries
Traditional approach
Prevent crashes, improve human behavior, control speeding, individual responsibility, react based on crash history
Safe systems approach
Prevent deaths and serious injuries, design for human error, reduce system kinetic energy, share responsibility, proactively identify and address risks
Safe systems pyramid (bottom up)
Socioeconomic factors, built environment, latent safety measures, active measures, education
Socioeconomic factors
Affordable housing near transit, zoning reform
Built environment
Roundabouts, curb extensions, raised crosswalks, sidewalks, bikeways
Latent safety measures
Signal timing, leading pedestrian intervals, air bags, automated emergency braking
Active measures
Signals and signs, in-vehicle collision warnings, seat belts, helmets
Education
Driver education programs, Slow Down campaigns
