|
|
| Re: ''World Class Bus Rapid Transit'' for Woodhaven Blvd... lol (299792) | |||
 |
|||
| Home > BusChat | |||
|
[ Read Responses | Post a New Response | Return to the Index ] |
|
||
|
Re: ''World Class Bus Rapid Transit'' for Woodhaven Blvd... lol |
|
|
Posted by RIPTA42HopeTunnel on Wed Nov 12 15:33:46 2014, in response to Re: ''World Class Bus Rapid Transit'' for Woodhaven Blvd... lol, posted by BrooklynBus on Wed Nov 12 12:45:58 2014. But if you do not prohibit left turns you either can't have three through travel lanes as DOT is insisting on, or you have to suspend the bus lane in that area.No, you just narrow the median to accommodate the left turn lane. It fits, but the policy in the conceptual design is not to allow left turns at SBS "stations." The merge for buses will just occur before Cooper instead of after Metropolitan. And the bus gets to block traffic a lane of traffic at the Metropolitan station. I have been informed that others attending the meeting also expressed the same concerns about Metropolitan and Rockaway Blvd as I have. Good; hopefully they will look at it and refine the concepts accordingly. If they have nothing to hide, why isn't it on line? Well, perhaps someone in the public is a traffic engineer like yourself who could educate the public and ask intelligent questions if those data were made public. Perhaps it isn't finalized yet. West 181st Street is public. So what are you trying to say? Since I was there at 3 PM, and the slide says the peak is from 3PM to 7PM, that I have seen the peak turning movements? If so, then you know absolutely nothing about travel on Woodhaven Boulevard. The peak isn't reached at 3PM and maintained at that level until 7 PM. Traffic volumes begin to increase at 3PM, reach their peak between about 5 to 6 PM and then decline until 7 PM, when they start rapidly falling. The number of cars traveling on Woodhaven at 6PM is much more than at 3 PM, perhaps as much as 50% higher. That's NYCDOT's traffic count, not mine. NYSDOT's 2010 count shows southbound traffic peaking between 5 and 6 p.m., but it's 16 percent higher than 3 p.m., not 50 percent. A protected turn lane as well as a parking ban in the right lane (which I initially said would be required and you didn't recognize the need for) would be required. You said that long trucks could make the left from the "non-existing right lane" although cars could be parked there. Without parking restrictions that turn for trucks may not even possible. Maybe I didn't specifically say it, but I assumed parking would be prohibited approaching the intersection. I thought that was obvious from overlaying a truck along the curb line. No I did not use a stopwatch. What difference would it make if it was one minute and 45 seconds or two minutes and 15 seconds? The point is that it is about two minutes when traffic is far from its heaviest and when the left turn into Metropolitan is still allowed. The difference would be 30 seconds (or three Levels of Service). The fact that you hyperbolically estimate changes in hourly traffic volume also lead me to believe you hyperbolically estimate changes in travel time. I didn't realize that being a traffic engineer entitles you to pull numbers out of thin air without even seeing Woodhaven in operation. I'm pulling nothing out of thin air. "About 15 seconds" was the time you said you waited to turn left from Cooper onto Metropolitan. If those half dozen cars were not passing me on the right while I was waiting for clearance to make my left turn, probably four of them would have missed the green signal and delayed them an additional 30 seconds until the next traffic cycle. If there were other cars wishing to make that left turn, they might have missed a second signal and been delayed by over a minute. Which is why such a change shouldn't happen without also looking at signal timing and lane assignments. I never said right turns from Woodhaven to Metropolitan would be prohibited. What I said was that if left turns were prohibited from Woodhaven to Metropolitan from both the south and the north as is currently proposed, the following would occur. I misread; I thought you said southbound Woodhaven to westbound Metropolitan would also be diverted to Cooper. Some northbound lefts from Woodhaven might also be diverted to Cooper (that seems to be the idea in the concept, anyway), but they could also use 73rd Avenue. The 11 cars I saw lined up to make the left from Woodhaven northbound onto Metropolitan westbound, would now be required to turn at Cooper and would be going westbound at Cooper. The other 11 cars I saw waiting to make a left from Woodhaven southbound to Metropolitan eastbound, would also be funneled into Cooper westbound on the same block between Woodhaven and Metropolitan. That is 22 extra cars for each traffic cycle. Let's look at each turn separately and assume the cycle is 60 seconds for Woodhaven and 60 seconds for Metropolitan and 15 seconds for the protected left turn phase. Eleven cars make the turn. Then the following cars have to wait two more minutes for the next left turn phase. That means that in one hour, there are 7 cycles in 15 minutes or 28 cycles in one hour. So 28 times 11 equal 308 extra cars for each turning movement or 608 vehicles turning per hour, not 1,320 vehicles per hour. That's a lot less than 22 cars per minute, which is 1,320 per hour, but it still relies on a lot of assumptions. Did you observe 11 cars arriving in each direction each cycle for the hour? Time the cycle? If 11 cars were waiting to turn when you arrived, are you sure they all arrived on a single cycle and there were none who didn't make it through on a previous cycle? No one turned left during the permitted phase? Any trucks? If we also include current traffic on Cooper, (cars coming from Woodhaven south and from Yellowstone) we are probably talking about 1,000 vehicles per hour. More possiblies and abouts. NYSDOT has a 2004 count on Cooper. The exact location isn't given, but westbound traffic peaks at 243 vehicles per hour. At 5 PM we could expect traffic demand to increase by about 50 percent higher than it is at 3 PM. Cooper could not possibly handle that type of traffic volume without becoming hopelessly congested even with two lanes of traffic, one of which would become a left turn lane near Metropolitan. That brings me back to my original point that the turn to Cooper could add as much as ten minutes to someone's trip. (The same would also be true at Rockaway Blvd.) It follows that your hyperbolic assumptions about traffic volumes would result in a hyperbolic increase in travel time. Your assumption is that you would be averaging less than 1 mile per hour along Cooper and Metropolitan. All these possibilities need to be worked out now before it is decided if left turns should be banned. It is irresponsible to first decide you will eliminate left turns, and then worry about the ramifications later and how to best deal with a bad situation when it is too late to redesign the SBS. Which is exactly what I've been saying. Nothing is "designed" right now; it's just lines on paper. First you look at concepts, then you see how/if the concepts work, then you design it. Woodhaven SBS is still at the looking at concepts stage. Seeing how DOT eliminated the 88th Street alternative by failing to realize it was used as a bypass alternative and made congestion worse, and how they also eliminated another bypass route during times of heavy congestion (by eliminating southbound traffic on Redding Street near Conduit Blvd) they have little interest in reducing traffic congestion. Eliminating the "88th Street alternative" eliminated a merge point that was a safety problem. It also took impatient cut-through traffic off of residential streets, which is a nice by-product. They are more concerned about making traffic move slower. Seems to me that they are more concerned with considering the fact that some people who aren't in cars also use streets. It's rapidly becoming standard practice around the country, so if it weren't the case in the one U.S. city where the majority of residents don't own a car there would be a serious problem. |
|
|
|