agreed that there are benefits of sharrows versus none but side of road placement in narrow lanes is being reported as problematic in the Seattle bicycling community.
we are seeing some fairly well placed sharrows and some poorly placed ones that wind up underneath parked cars, etc..... likely the codifiying of sharrow placement could use firming up.
To me this is what this forum is about, sharing info on what works and what doesn't so we can all help the codifying for placement to be firmed up. If you have pics or descriptions of problematic areas it would be appreciated.
Baltimore choosing to push the envelope and encourage side by side sharing with a sign designed for treatments in lanes where that action is unsafe seems a strong misuse of their intent.
Whoa! Where is this coming from? ALL sharrows are placed in lanes where there is not enough room for a bike lane, no? If there is not enough room for a bike lane then the lane is technically not safe for side by side sharing, no? So by your logic all sharrow placements that follow the minimum guidelines are a strong misuse of their intent. :wtf:
Let me emphatically say that Baltimore is following the guidelines on sharrow placement.
Personally I think you might be joining statements that were meant to be unrelated (or tangentially related) my apologizes if I was not clear. But it does seem to me if the deign specs for sharrows are x feet from the curb irregardless of lane width then logically there should be a ideal lane width and for lane widths that differ there's a strong possibility that the placement of the sharrow should change as well (and if so what the heck is that.) And that relates to my op (to rephrase) what is the ideal lane width and sharrow placement. So far the answer is sharrows in the center lane position but I don't think that was studied, if it was the guidelines and benefits are certainly worded very strangely for that.
And it seems to me that you are also criticizing the original placement/lane widths of sharrows and the study of the results that got sharrows this far in the standards process. This is not a point for me to defend.
Bekologist
05-17-08, 08:41 PM
no.
sharrows are being codified to be placed in lanes
TOO NARROW to be shared safely AND insufficient pavement width to install bike lanes.
they are NOT being developed to encourage sharing marginally wide lanes side by side.
Bekologist
05-17-08, 09:23 PM
I don't think baltimore is placing sharrows to standard if they are underneath parked cars in outside lanes, Barry. the federal MUTCD design mandate states that in a lane with shared parallel street parking the sharrow shall be placed A MINIMUM of 11 feet from the curb face.
where is baltimore installing them in these lanes that are going to have parallel parking in them, absent the parking restrictions? are they going to be 11 feet from the curb face?
Barry, I'd go get you pics but am only bicycling in cyberspace right now as i recoup from a broken hip. no mobility to go out and get pics.)
The Human Car
05-17-08, 09:54 PM
no.
sharrows are being codified to be placed in lanes too narrow to be shared safely AND there is insufficient pavement width to install bike lanes.
they are NOT being developed to encourage sharing marginally wide lanes side by side.
So you are saying that even if I observe all the safe passing and improved cyclists positioning distances per the sharrow study (http://www.bicycle.sfgov.org/site/uploadedfiles/dpt/bike/Bike_Plan/Shared%20Lane%20Marking%20Full%20Report-052404.pdf) if I also observe some motorist being able to do all that plus stay in the same lane (not mentioned in the study) somehow Baltimore is doing it all wrong? :rolleyes:
Is it a requirement of sharrows that every single driver cross the lane line? Is it better for sharrows to require every single driver to cross the lane line or if there is sufficient width allow some (smaller) vehicles to pass within a lane (provided no compromise is made on the safe passing distance of the cyclist?) And if we don't want the latter what is the solution, narrow the lane or move the sharrow out?
The Human Car
05-17-08, 10:19 PM
I don't think baltimore is placing sharrows to standard if they are underneath parked cars in outside lanes, Barry. the federal MUTCD design mandate states that in a lane with shared parallel street parking the sharrow shall be placed A MINIMUM of 11 feet from the curb face.
where is baltimore installing them in these lanes that are going to have parallel parking in them, absent the parking restrictions? are they going to be 11 feet from the curb face?
Baltimore's policy is not to place sharrows underneath parking (but a goof might still exist, dang lowest bidders.) Sharrows might be used on sections of the road in discussion where parking is NEVER permitted (near the curb most likely.)
[Heal well and I hope your on your bike soon.]
Bekologist
05-17-08, 10:40 PM
Is it better for sharrows to require every single driver to cross the lane line or if there is sufficient width allow some (smaller) vehicles to pass within a lane (provided no compromise is made on the safe passing distance of the cyclist?) And if we don't want the latter what is the solution, narrow the lane or move the sharrow out?
I wonder. i don't think sharrows should be encouraging side by side lane sharing. they are not indicated to do so, therefore, IMO centered lane position would by design be a more logical placement of a sharrow.
I think encouraging side of road riding via sharrows to encourage possibly unsafe lane sharing in a lane considered too narrow to safely share IS a misuse of sharrows, yes.
perhaps that's why baltimore is looking to narrow those lanes, barry??? and why advocates in Seattle and Portland are looking at center of narrow lane treatments, rather than widening lanes for sharrow use?
hey, not trying to ride you too hard, I've just got a little extra down time with no biking, no work, so 'riding' in bike forums is a great escape from my malady.
The Human Car
05-18-08, 01:03 AM
I wonder. i don't think sharrows should be encouraging side by side lane sharing. they are not indicated to do so, therefore, IMO centered lane position would by design be a more logical placement of a sharrow.
If somebody put me in charge that's how I would spec out sharrows, the problem is that is NOT how the placement guidelines work out (unless they are always tweaked) nor does it appear that is what was studied.
I think encouraging side of road riding via sharrows to encourage possibly unsafe lane sharing in a lane considered too narrow to safely share IS a misuse of sharrows, yes.
But what makes narrow lane sharing unsafe? Is it not the lack of safe passing distance? But sharrows do not encourage unsafe passing distance, in fact they encourage a safer passing distance so the supposed lack of safety is not with the sharrow but with the too wide of a narrow lane. Now the usage guidelines (http://www.liveearnplaylearn.com/Portals/0/Section1.pdf) say 4' from the curb in a wide outside lane. Heavy sigh, now I'm confused, are sharrows for wide lanes or are they for narrow lanes? Or does lane width make no difference? If the lane width makes no difference why are people looking into changing the spec on how sharrows are placed?
A bit of a tangent to make a point: Baltimore likes to avoid delimiting parallel parking spaces because they can accommodate 10% more cars by not having every slot being large enough to accommodate a Chevy suburban. I believe sharrows can work in a similar manner, just because a lane is not wide enough to share side by side with a bus does not mean that it is not wide enough to safely share with smaller vehicles. (Isn't there 2'-4' difference in width between a bus and standard cars? So lets say we have a road where buses (and similar sized vehicles) are prohibited, wouldn't that allow us to reduce a 14' sharable lane by 2'-4'. Which gives us a 10'-12' lane sharable by standard cars. And with sharrows, as long as buses (and similar sized vehicles) are crossing the line does that not also give us a 10'-12' lane sharable by standard cars?)
perhaps that's why baltimore is looking to narrow those lanes, barry??? and why advocates in Seattle and Portland are looking at center of narrow lane treatments, rather than widening lanes for sharrow use?
The change from 10',12' to 11',11' is just a temporary stripe that opened up a tangent discussion locally about preferred lane widths for sharrows in general if we have that option (if you have a few feet extra where would you put it?) Which I thought might be an interesting discussion for here and so far it has not been going as expected but hay, that's life.
hey, not trying to ride you too hard, I've just got a little extra down time with no biking, no work, so 'riding' in bike forums is a great escape from my malady.
I'm not trying to ride you too hard ether, so I hope you find some entertainment here.
This discussion brings to mind a joke:
Clyde was walking by Henry's place and sees him sawing his barn door. "Whacha doing?"
I'm making my barn door taller because when I bring my mule in his ears hit the top of the doorway.
"Wouldn't it be easer just to dig away some of the floor?"
Heck, it's his ears that are too big not his legs.
Bekologist
05-18-08, 07:50 AM
Barry, I find this both entertaining AND very informative.
Now I'm confused too. NOWHERE can I find any indication that sharrows are to be implemented to encourage side-by-side lane sharing (except your baltimore PDF), they are indicated for lanes too narrow to be safely shared. I did find ONE implementation in Oakland where the intent is lane sharing, but that was a treatment on a 14' WOL and find no supporting federal documentation for this.
why ANY bicyclist would want to encourage side by side sharing in a ten foot lane is beyond me. That's patently unsafe IMO.
crossing a lane line is NOT 'lane sharing' in my opinion. only parallel travel with both car and bike within the lane is lane sharing. building a streetscape where a large % of vehicles have to cross into another lane to pass the bicyclist is a clear indication that lane is too narrow to safely share.
14 feet is fairly easy to share with cars (even though I don't like to do that) 18 feet even easier. I would have no objection having sharrows right biased in a 14 to 18 foot lane, but that is not what sharrows are being indicated for.
sharrows , for low speed streets with lanes too narrow to be safely shared, and not enough width for bike lanes. not the baltimore paradigm. I need to dig some more, but the 2007 NCTUCTD abstract revisions re: sharrows seems not to indicate any wide lane sharrow placements.
Additionally, everything I read indicates the lateral placement is a decision best left to local planners and that the distance minimums from the curb are NOT the maximums, and that municipalities are left wide open to increase sharrow placement from edge of road to increase cyclist safety.
DCCommuter
05-18-08, 07:17 PM
A bit of a tangent to make a point: Baltimore likes to avoid delimiting parallel parking spaces because they can accommodate 10% more cars by not having every slot being large enough to accommodate a Chevy suburban. I believe sharrows can work in a similar manner, just because a lane is not wide enough to share side by side with a bus does not mean that it is not wide enough to safely share with smaller vehicles. (Isn't there 2'-4' difference in width between a bus and standard cars? So lets say we have a road where buses (and similar sized vehicles) are prohibited, wouldn't that allow us to reduce a 14' sharable lane by 2'-4'. Which gives us a 10'-12' lane sharable by standard cars. And with sharrows, as long as buses (and similar sized vehicles) are crossing the line does that not also give us a 10'-12' lane sharable by standard cars?)
There's a problem with this analogy. Parking is static, traffic is dynamic. If you think you can squeeze into a parking spot, and it turns out you were wrong, you move on to the next one, no harm. If you think you can squeeze past a cyclist and you're wrong, it's a problem -- mostly for the cyclist.
They don't design roads so that the bridges are strong enough for most of the permitted vehicles, or the overpasses high enough for most of the permitted vehicles -- they put weight and height limits on. It makes no more sense to design roads that are not wide enough for all the vehicles using them than it does to design roads that are not high enough for all the vehicles using them. But there's a reason why you won't see width restrictions on roads, the way you see height restrictions and weight restrictions. Unlike weight and height there is a single federal regulation for width, 8'6", and states are prohibited from varying from it if they want federal highway money.
The Human Car
05-18-08, 09:29 PM
Now I'm confused too. NOWHERE can I find any indication that sharrows are to be implemented to encourage side-by-side lane sharing (except your baltimore PDF), they are indicated for lanes too narrow to be safely shared. I did find ONE implementation in Oakland where the intent is lane sharing, but that was a treatment on a 14' WOL and find no supporting federal documentation for this.
In the original study (http://www.bicycle.sfgov.org/site/uploadedfiles/dpt/bike/Bike_Plan/Shared%20Lane%20Marking%20Full%20Report-052404.pdf) it looks like there was ~4' to 10' of lane to the left of the sharrow and all widths worked. There is a gap of lane widths to the left of sharrows not studied which is 7'-9'.
So it seems to me that your assertion is that narrow lanes work or wide lanes work but there is a unverified "danger zone" in between. Ok lets look at the low end of 7' plus 5' (of sharrow) = a 12' lane. Where is an adequate VC position of a 12' lane? Is it only dead center or does the right tire track work as well? Dead center would be at 6' and the right tire track would be at 3' and sharrows put a cyclist at a "dangerous" 4' even though it is more centerish then a right tire position. I'm not buying that this is a dangerous position for a cyclists. For practical purposes I rarely see 13' lanes so the next bump up is 14' which we agree is sharable. So it seems to me you have to make a case of why 4' from the curb is a dangerous place to be in a 12' lane.
why ANY bicyclist would want to encourage side by side sharing in a ten foot lane is beyond me. That's patently unsafe IMO.
If my math is right a sharrow 4' in to a 10' lane was studied on Second Street. Supposedly it worked well.
sharrows , for low speed streets with lanes too narrow to be safely shared, and not enough width for bike lanes. not the baltimore paradigm. I need to dig some more, but the 2007 NCTUCTD abstract revisions re: sharrows seems not to indicate any wide lane sharrow placements.
Interesting even though use on wide lanes was studied.
The Human Car
05-18-08, 09:34 PM
There's a problem with this analogy. Parking is static, traffic is dynamic. If you think you can squeeze into a parking spot, and it turns out you were wrong, you move on to the next one, no harm. If you think you can squeeze past a cyclist and you're wrong, it's a problem -- mostly for the cyclist.
I'll be sure to tell the next mini cooper that passes me that he has to pass me like he was a bus and give me a total of 7 feet of safe passing distance to make up for the lack of width his car has. :rolleyes:
Bekologist
05-18-08, 09:47 PM
I wonder why sharrows are not codified for wide lanes in the 2007 NCTUCTD revisions on sharrows?
oh, and when I'm riding a 12 foot lane, that's unsafe for sharing and i will be in the center or left side of the lane, even encroaching into the space further left for greater visibility.
DCCommuter
05-18-08, 10:15 PM
I'll be sure to tell the next mini cooper that passes me that he has to pass me like he was a bus and give me a total of 7 feet of safe passing distance to make up for the lack of width his car has. :rolleyes:
It's not the mini coopers I'm worried about, it's the buses.
Somehow I don't think the mini drivers worry about bridge weight limits and overpass heights either.
DCCommuter
05-18-08, 10:36 PM
oh, and when I'm riding a 12 foot lane, that's unsafe for sharing and i will be in the center or left side of the lane, even encroaching into the space further left for greater visibility.
Twelve feet is the magic number that is the no-man's-land of lane-sharing. Eleven feet is by law presumed not to be sharable here. Thirteen feet is officially considered enough for a bike lane. Twelve? Depends on conditions.
As I noted earlier, around here the sharrow is authorized only in 12-foot lanes, and it is painted on the right edge. When sharrows are painted the minimum width for a parking lane is reduced to eight feet, which allows non-sharable 10' lane to be magically transformed into a 12' sharable lane -- accomplishing with paint what would otherwise require messy and expensive road widening!
randya
05-19-08, 09:35 AM
concur with the comments about DC's poor use of bike lanes.
do you mean the advocates lobbyling for them, or cities placing them centered in narrow lanes? COZ in Seattle there's movement afoot to do exactly that....
I mean both - advocates actually wanting them in the middle of the lane and/or the city engineer actually putting them there. Portland is well on its way to total separation la la land...
:(
The Human Car
05-21-08, 07:22 AM
I wonder why sharrows are not codified for wide lanes in the 2007 NCTUCTD revisions on sharrows?
oh, and when I'm riding a 12 foot lane, that's unsafe for sharing and i will be in the center or left side of the lane, even encroaching into the space further left for greater visibility.
I suspect the NCUTCD wants only bike lanes for wide lanes :(
That's the way I ride in 12' lanes without sharrows as well. With sharrows I ride leftmost so that puts me ~5' out in the lane and so far it seems to work well enough.
And to others let me stress that so far wider vehicles do seem to pass cyclists in sharrows with extra space (as opposed to the average riding near gutter cyclist) and sharrows do NOT encourage wide vehicles to pass in the same lane per my observations and what was reported in the study.