Ralston Lane Reassignment2
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Ralston Lane Reassignment2

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Proposal to add dedicated right turn lane to Ralston at El Camino in Belmont, CA. Addresses both concerns raised by Belmont traffic commission when they considered the proposal in December 2009.

Proposal to add dedicated right turn lane to Ralston at El Camino in Belmont, CA. Addresses both concerns raised by Belmont traffic commission when they considered the proposal in December 2009.

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Ralston Lane Reassignment2 Presentation Transcript

  • 1. Ralston & El Camino lane reassignment proposal John Boykin, January 2010 650-906-5567 650-802-9998 On December 10, 2009, the Belmont traffic safety commission considered my proposal to reassign lanes on eastbound Ralston at El Camino, to create a dedicated right turn lane. The commission was reluctant to do so, citing two concerns. This presentation is to address both concerns. This presentation must be viewed in Slideshow mode.
  • 2. Ralston lane reassignment (at El Camino) John Boykin 906-5567, john@wayfind.com The Problem Eastbound Ralston has no dedicated right turn lane onto southbound El Camino. Yet it has 2 (underutilized) left turn lanes. So drivers wanting to go toward San Carlos must share a lane with through traffic. This creates a bottleneck, backing up cars and impeding the smooth flow of traffic at Belmont’s most important intersection.
  • 3. Ralston lane reassignment (at El Camino) John Boykin 906-5567, john@wayfind.com The solution: Reassign lanes Status quo Proposal
  • 4. Concern 1: Lanes offset (jog) The commission’s main concern was that, if we shifted the two through lanes to the left, they would no longer line up with the lanes on the opposite side of El Camino. Cars would have to jog to the right as they crossed the intersection.
  • 5. Ralston lane reassignment (at El Camino) John Boykin 906-5567, john@wayfind.com True. The question is, How would this offset compare with existing nearby offsets that we take for granted?
  • 6. Ralston lane reassignment (at El Camino) John Boykin 906-5567, john@wayfind.com Widening road mouth downstream The offset could be reduced with a modest modification to the east side of Ralston (downstream). Let’s zoom in on the area inside the circle.
  • 7. Ralston lane reassignment (at El Camino) John Boykin 906-5567, john@wayfind.com Status quo Modify from this… Widening road mouth downstream Island is 9’ wide—about the width of 1 lane of traffic Road mouth now wider, angling toward incoming cars & lessening offset All remaining pictures will show this modification … to this
  • 8. Ralston lane reassignment (at El Camino) John Boykin 906-5567, john@wayfind.com So here is the offset we would have (dotted yellow line). We’ll come back to this. But first, let’s look at a few nearby precedents for comparison.
  • 9. Precedent 1: 180 ft. upstream
  • 10. Ralston lane reassignment (at El Camino) John Boykin 906-5567, john@wayfind.com The first precedent is right here —180 ft. upstream. Let’s zoom in on it.
  • 11. Ralston lane reassignment (at El Camino) John Boykin 906-5567, john@wayfind.com …and straighten out again here. Lanes go straight here… …start jogging here to the right …
  • 12. Ralston lane reassignment (at El Camino) John Boykin 906-5567, john@wayfind.com How much is this existing upstream offset that we take for granted? Let’s trace it to find out. First, let’s imagine what we would have if the lanes continued going straight.
  • 13. Ralston lane reassignment (at El Camino) John Boykin 906-5567, john@wayfind.com Now, let’s imagine extending the downstream lane divider just to see where that would lead.
  • 14. Ralston lane reassignment (at El Camino) John Boykin 906-5567, john@wayfind.com It now becomes apparent that traffic is currently jogging over about one lane’s worth. Here’s another view of that
  • 15. Ralston lane reassignment (at El Camino) John Boykin 906-5567, john@wayfind.com The blue line here traces the offset.
  • 16. Ralston lane reassignment (at El Camino) John Boykin 906-5567, john@wayfind.com Now, let’s see how that same offset would look if we were to pick it up and superimpose it over the intersection. Blue line = existing upstream offset
  • 17. Ralston lane reassignment (at El Camino) John Boykin 906-5567, john@wayfind.com Here is the existing offset superimposed over the proposed lane configuration. Let’s compare this with the proposed offset.
  • 18. Ralston lane reassignment (at El Camino) John Boykin 906-5567, john@wayfind.com So the proposed lane configuration would give us an offset nearly identical to the one we already have 180 feet upstream. Blue line is existing upstream offset. Yellow dashed line is proposed offset. Now let’s zoom back out to see the whole picture.
  • 19. Ralston lane reassignment (at El Camino) John Boykin 906-5567, john@wayfind.com … to here. The proposal basically just relocates the existing jog from here…
  • 20. Ralston lane reassignment (at El Camino) John Boykin 906-5567, john@wayfind.com So instead of jogging before the intersection…
  • 21. Ralston lane reassignment (at El Camino) John Boykin 906-5567, john@wayfind.com …traffic would go straight and then do the jog through the intersection. Northbound and southbound cars would peel off to the left and right.
  • 22. That’s just the closest precedent. Let’s look briefly at 2 more.
  • 23. Precedent 2: El Camino at Holly
  • 24. Holly Northbound El Camino at Holly in San Carlos Green line traces the offset
  • 25. Holly Now let’s transpose this offset onto the proposed intersection Green line = existing offset at El Camino & Holly
  • 26. Holly The proposal nearly matches the offset we take for granted at Holly. Yellow dashed line is the proposed offset. Green solid line is the El Camino-Holly offset.
  • 27. Precedent 3: Woodside Rd. & Veterans (southbound 101 offramp onto Woodside Rd.)
  • 28. Ralston lane reassignment (at El Camino) John Boykin 906-5567, john@wayfind.com Woodside Rd. Offramp from southbound 101 onto westbound Woodside Rd. in Redwood City. Red line traces the offset.
  • 29. Ralston lane reassignment (at El Camino) John Boykin 906-5567, john@wayfind.com Woodside Rd. Woodside Rd. offsets to the left. Ralston would offset to the right. So, to superimpose Woodside Rd.’s offset onto Ralston’s, we first need to make a mirror image of it… Red line = existing offset at Woodside Rd.
  • 30. Ralston lane reassignment (at El Camino) John Boykin 906-5567, john@wayfind.com Woodside Rd. …like this. Then we’ll need to pivot it a little clockwise to match Ralston’s orientation… Mirror image
  • 31. Ralston lane reassignment (at El Camino) John Boykin 906-5567, john@wayfind.com Woodside Rd. …to this. Pivot point …from this…
  • 32. Ralston lane reassignment (at El Camino) John Boykin 906-5567, john@wayfind.com Comparison The proposed offset is much less than the offset we take for granted at Woodside Rd. Red solid line is Woodside Rd. offset. Yellow dashed line is proposed offset.
  • 33. Let’s review how the 3 nearby precedents compare with the proposal
  • 34. PROPOSAL Ralston lane reassignment (at El Camino) John Boykin 906-5567, john@wayfind.com …and much less than Woodside Road’s … and to Holly’s… Here’s the offset resulting from the proposed lane reconfiguration… …very comparable to the one 180 feet upstream on Ralston…
  • 35.
    • In short, we need not be concerned about the offset resulting from the proposed lane reconfiguration, because the new offset would be very comparable to existing offsets:
    • 180 feet upstream on the very same road
    • northbound El Camino at Holly
    • … and much less than the existing offset at Woodside Rd.
    The biggest problem at both Woodside Rd. and Holly is poor guidance through the intersection to the correct lane on the opposite side. We must put guidance buttons in the Ralston-El Camino intersection.
  • 36. Concern 2: Moving left The commission’s second concern was that, if we shifted the two through lanes to the left, cars approaching the intersection would have trouble moving left because of the two-way turn lane in the middle of the road. It is not at all certain that that would actually be a problem. But even if it were, it could be easily mitigated.
  • 37. Ralston lane reassignment (at El Camino) John Boykin 906-5567, john@wayfind.com Status quo Proposal Walgreens entrance Simply end the two-way turn lane sooner. It serves no purpose past the Walgreens entrance. Cars could then start moving left sooner.
  • 38.
    • Summary
    • The traffic commission should reconsider the proposal to create a dedicated right-turn lane from eastbound Ralston onto southbound El Camino. The commission's two key concerns can be put aside because
      • the offset that would be created through the intersection is comparable to other nearby offsets that we have no problem with now
      • moving left upstream can be easily facilitated
    Status quo New
  • 39. We would only need to make 4 modest modifications. 1. Taper the island on the east side of the street and re-angle the left-turn lane with it Status quo Island tapered
  • 40. 2. Paint new lane stripes and direction arrows Status quo: Jog before intersection New: Jog through intersection
  • 41. 3. Add guidance buttons through intersection Like Holly does well here (Not like Holly does poorly here)
  • 42. 4. Repaint 2-way turn lane to end earlier Status quo New Walgreens entrance
  • 43.
    • Fix the bottleneck
    • Creating a dedicated right-turn lane from eastbound Ralston onto southbound El Camino
      • will alleviate the bottleneck at Belmont’s most important intersection
      • will create an offset comparable to other acceptable offsets nearby
      • can be done with only modest modifications
    Status quo New John Boykin 906-5567 802-9998