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Roundabouts (RAB) and Channelized Turning Lanes (CTL)

Roundabouts (RAB) and Channelized Turning Lanes (CTL). Dona Sauerburger, COMS November 16, 2012 CAOMS, San Diego www.sauerburger.org/dona. Outline of workshop. What are features of RABs and CTLs? How to recognize RABs and CTLs? Tasks Locating crosswalk Aligning and maintaining alignment

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Roundabouts (RAB) and Channelized Turning Lanes (CTL)

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  1. Roundabouts (RAB) and Channelized Turning Lanes (CTL) Dona Sauerburger, COMS November 16, 2012 CAOMS, San Diego www.sauerburger.org/dona

  2. Outline of workshop • What are features of RABs and CTLs? • How to recognize RABs and CTLs? • Tasks • Locating crosswalk • Aligning and maintaining alignment • Determining when to cross • Learning to recognize Situations of Uncertainty • Practice /experience • Brainstorm / problem-solve tasks

  3. Features of RABs and CTLs

  4. Roundabouts: An Informational Guide (NCHRP Report 672)http://safety.fhwa.dot.gov/intersection/roundabouts/fhwasa10006/

  5. Features of Roundabouts NOT mini-roundabouts or large traffic circles! • Circular vehicular pathway (counterclockwise) • Splitter islands • Crosswalks set back from “intersecting street” • Drivers entering RAB yield to traffic in the circle • No stop sign or signal

  6. Important: • How many lanes? • Turning radius?

  7. Channelized Turning Lanes “Porkchop island;” “Channelized lane”

  8. Exceptions Upstream/downstream

  9. Features of CTLs Usually: • Uncontrolled • Single lane • “Upstream” traffic yields to “downstream” traffic • Crosswalk at center USUALLY!

  10. Exceptions Two lanes

  11. Exceptions Two lanes

  12. Exceptions Stop sign!

  13. Considerations for CTL • IMPORTANT: does it have a: • deceleration lane? • acceleration lane? • IMPORTANT: is the turning radius • Narrow? (slower vehicles) or • wide? (drivers can go faster)

  14. No acceleraton/deleration Acceleration lane Deceleration lane Deceleration and acceleration

  15. Turning radius

  16. Wide radius

  17. Wide radius

  18. Narrow radius

  19. OK, now the nitty-gritty! TASKS for the blind traveler: • Recognize RAB or Right-turn-lane • Find crosswalk • Align • Determine when to start crossing • Maintain alignment / recover from veer

  20. TASK #1: Recognizing RAB or CTL

  21. RAB: What might you notice? • Traffic approaching and leaving roundabout seem to be split at the island (making the shape of a “Y” with leg) • NO consistent pattern!! • some vehicles don’t slow down, others on the same street slow down and proceed, some stop and wait; • no turn-taking like at a signal. • Perpendicular traffic not unusual except: • Only can hear traffic going to the right, and • Can sometimes hear muffled traffic going to the left • At some RABs, approaching traffic seems to turn right but then continues straight • Splitter island may make street sound wider

  22. Task #2: Find crosswalkAssuming there is one! What is a crosswalk? (Marked/unmarked) Varies from state to state • Usually “extended pedestrian path” • Sometimes “corner to corner” • Sometimes “extended ped path from BOTH directions”

  23. Find crosswalkAssuming there is one! Find crosswalk at Roundabout? (from notes) Not predictable! • Shoreline on curb side (either along your approach or go to the circle and turn around and look). • Listen to people (they are likely to be at the crosswalk) • Curb cuts are likely to be in crosswalk especially at roundabouts

  24. Find crosswalkAssuming there is one! Find crosswalk at Right-turn lane? (from notes) • Shoreline along street to find curb cut • Crosswalk is often between upstream and downstream but sometimes along the downstream street • Crossing at downstream (with no acceleration lane) • Advantages • Drivers are already slowing down or stopping to yield to traffic • recovery from veer may be easier • DISadvantages • drivers are looking toward the traffic, away from you, andare not expecting you!!! • if that is not where the crosswalk is, you don’t have the right of way

  25. Align! (?) At Roundabout (from notes) • Cut-through for splitter island may not straight • Maybe align with perpendicular traffic (but be aware it may already be turning) • Use individual features that you know are straight at that intersection (“back-up strategy”)

  26. Align! (?) At Separate right-turn-lane no reliable solutions (Previous workshop participants had no solutions!) • Listen to waiting vehicles and aim to the front of them – reliable??? • Can you rely on direction of curb cut? reliable???

  27. Align! (?) At Separate right-turn-lane (NOT from notes – no solutions!) • Listen to waiting vehicles and aim to the front of them IS NOT RELIABLE. • Can you rely on direction of curb cut? NO – NOT RELIABLE Reliable “back-up” strategy: Use individual features that you know are straight / fixed at that intersection

  28. Maintain alignment ROUNDABOUT (from notes) • Use veer-reduction strategies such as crossing quickly • Use sound of perpendicular traffic in the far lane • Use any permanent sound features that may exist to walk toward or along • Use tactual clues in crosswalk if they exist • Use slope of ground in the street while crossing. HOW TO CORRECT A VEER: • Not usually a problem

  29. Maintain alignment CHANNELIZED TURNING LANE: (from notes) • Use sound of locator tone if it is on island • Listen to where the cars are waiting at upstream street and walk toward the front of them (if the stopbar is at the corner) HOW TO CORRECT A VEER (missed island) • Develop skill of being able to hear vehicles pass and then know when you’ve reached the lane where they were (this skill REQUIRES TRAINING). Then: • listen to the traffic on the other side of island to determine how far away it is. • When you cross, if you walk far enough to have reached where they were, you know when you’ve gone too far! • When you determine you’ve missed the island because you’ve walked too far and haven’t reached it • turn around 180 degrees and go back toward the curb where you started OR • if you feel the street sloping, follow the slope down because it goes to a gutter and curb.

  30. Determine when to start cross No stop sign or traffic signal, SO There are only 3 conditions for crossing: • Gap in traffic long enough • Vehicles are there but they yielded • Trust that if there is a vehicle coming, driver will yield

  31. Determine when / whetherto cross No rules ! ! ! • Consider advantages / disadvantages (what are the risks) and how to deal with disadvantages (decrease risk) • Make decisions about crossing based on: ACCEPTABLE RISK! • Choices: • CROSS because risk is acceptable – use: • Gap in traffic • Yielding vehicles • Trust drivers to yield • DON’T CROSS because risk is NOT acceptable • use alternatives

  32. Determine when / whetherto cross Cross During Gap in Traffic (ASSUMING YOU HAVE GAPS IN TRAFFIC LONG ENOUGH!) Skill needed: Recognize whether • you have enough warning (“Situation of Confidence”) OR • you can’t hear/see far enough for warning (“Situation of Uncertainty”)

  33. Situations of uncertainty

  34. Determine when / whetherto cross Cross During Gap in Traffic (ASSUMING YOU HAVE GAPS IN TRAFFIC LONG ENOUGH!) Skill needed: Recognize whether • you have enough warning (“Situation of Confidence”) • you can’t hear/see far enough for warning (“Situation of Uncertainty”) Traveler needs to: • Determine width of street • Understand (intuitively) own crossing time • Recognize when not long enough warning Train participants to recognize Situation of Uncertainty/Confidence 41:00

  35. Situation of Uncertainty? What to do? Analyze risk! • Do you have the right of way? • How likely are you to be surprised? • If you are, how likely is it that will it stop for you? • If it doesn’t stop for you, how likely is it that you will be seriously injured or killed? Practice analyzing risk of situation 35:22

  36. Determine when / whetherto cross Cross When Drivers Have Yielded Skill needed: Confirm all drivers stopped • Ideas to get drivers to stop: 32:29; 35:22 • Ideas to confirm yield? • ETA • Provoke honk (hold up sign / cup ear)

  37. Determine when / whetherto cross TRUST That Drivers Will Yield Analyze likelihood that drivers will yield.

  38. HAWKS (now called PHBs) and raised crosswalks were tested in the 3-78 project and the PHBs were tested at that Michigan roundabout.http://onlinepubs.trb.org/onlinepubs/nchrp/nchrp_rpt_674.pdfandhttp://www.rcocweb.org/Lists/Publications/Attachments/126/HAWK%20Final%20Report%202011.pdfBut the short version is that where tested, they improved access for blind peds. PHBs basically pedestrian pushbuttons and APS and walk indications as part of the setup; still have to be aware of potential red light running, etc. Raised crosswalks just seemed to really slow down the cars, and make them more aware of the potential for pedestrians? I'm not sure; there was still the potential for multiple threat (that second lane) but somehow it just calmed things down enough that they all stopped.Basically the Michigan installations were a result of an ADA complaint and they are now installing PHBs at all their multilane roundabouts.

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