West Harlem CB Members to DOT: Let Drivers Use Neighborhood as Shortcut

Key community board members in West Harlem say having anything less than two lanes in each direction will gridlock Riverside Drive. Photo: Google Maps
Key community board members in West Harlem say anything less than two lanes in each direction will gridlock the Riverside Drive viaduct. Photo: Google Maps

Riverside Drive in West Harlem is shaping up to be another test case for DOT’s commitment to safety improvements, and whether the agency will allow ignorance of basic street design principles and fear of change guide its decisions.

DOT didn’t put bike lanes in its road diet plan for Riverside Drive. Now, key members of Community Board 9 don’t want a road diet in the plan, either. DOT says that without the lane reduction, which will lower the design speed of the street, it won’t go along with requests to reduce the speed limit on Riverside to 25 mph.

The project includes pedestrian islands and curb extensions along Riverside Drive, 116th Street, and 120th Streets between 116th and 135th Streets. Its centerpiece is a road diet, from two lanes in each direction to one, on the viaduct that carries Riverside over West Harlem [PDF].

CB 9 transportation committee chair Carolyn Thompson and Ted Kovaleff, who served as CB 9 chair in the 1990s, spent much of Wednesday night’s meeting trying to maintain as many car lanes as possible on Riverside Drive.

Kovaleff said that he used to frequently drive to Vermont on Friday afternoons, and found that spillover traffic from the West Side Highway would clog Riverside, backing up on the viaduct. Removing one lane, he said, would lead to total gridlock. DOT project manager Dan Wagner said his analysis showed the viaduct road diet would slow driver speeds without leading to excessive back-ups, but Kovaleff wasn’t convinced. It would become a terminal bottleneck,” he said, “and that bottleneck would lead to increased pollution.”

“The asthma rate in this community, it’s horrible,” Thompson added. She also claimed that buses wouldn’t be able to operate on the viaduct with one lane in each direction.

Kovaleff didn’t evince much concern about dangerous speeding on the viaduct — and wasn’t convinced, despite ample evidence, that road diets work. “If people are gonna speed, whether it’s one lane in each direction, or two lanes in each direction, they’re gonna press down on the accelerator,” Kovaleff said. “And, you know, I don’t really care if people go 50 miles an hour on the viaduct.”

The viaduct, it turns out, is the most dangerous stretch in the Riverside Drive project area. Outside the viaduct, from 116th Street to Grant’s Tomb, ranks in the middle third of Manhattan corridors for crash rates, Wagner said. When the viaduct is also taken into consideration, from Grant’s Tomb to 135th Street, the project area jumps into the top third of the borough’s most dangerous corridors.

No bike lanes, and maybe not even a road diet, for the Riverside Drive viaduct. Photo: DOT [PDF]
No bike lanes, and maybe not even a road diet, for the Riverside Drive viaduct. Photo: DOT [PDF]
Martin Wallace, another committee member, said he cares quite a bit if drivers speed by him on the viaduct when he bikes on Riverside. He also suggested that the board ask DOT to test out a road diet on Riverside and remove it if the change did end up worsening traffic backups.

Kovaleff asked if DOT could simply reduce the speed limit on Riverside without a road diet. After the city’s default speed limit was lowered to 25 mph, DOT kept the 30 mph signs up on Riverside. Council Members Helen Rosenthal and Mark Levine have asked DOT to bring Riverside in line with other city streets, and DOT said last month that it would change the speed limit as part of this project.

On Wednesday, Wagner noted a caveat: the speed limit change could only happen with the road diet, not without it, he said. Board members were skeptical, given that DOT has established 25 mph speed limits on other roads with similar designs.

“The request for 25 miles an hour has been very loud and very heard on Riverside Drive. That indicates to us that this street should be a neighborhood street rather than a commuter street,” Wagner said. If the community board were interested in a road diet along the entire length of Riverside, he said, “we would be receptive to that request.”

But Thompson and Kovaleff seem intent on maintaining Riverside as an attractive shortcut when the West Side Highway is congested. “It may not supposed to be [a commuter route],” Kovaleff said, “but the fact of the matter is that it is.”

“People do use it as a cut-through,” Wagner countered, “and with design changes we hope to change that for the betterment of the neighborhood.”

Kovaloff also expressed skepticism about a curb extension on the southeast corner of Riverside and 116th Street, claiming that squaring off the corner adjacent to a curved building will “have a possible negative impact on the way the building looks.” He also repeated his call, from last month’s meeting, for DOT to eliminate pedestrian islands planned for 120th Street and use the space for angled parking, to squeeze in more car storage space.

The CB 9 transportation committee has tentatively scheduled another hearing on the plan for March 5. Wagner said funding requirements mean that DOT must start construction by September, with work to finish in 2016.

  • JudenChino

    What’s so infuriating is that Riverside Drive is the Hudson Greenway Alternative for biking to the GWB. So on nice days, there are a lot of fast bikers on this stretch of road. I do not want this treated as some alternative to West Street. What the fuck is the matter with these people? They’re so stupid. They think so simply. We must keep traffic moving at all costs. Fuck them. I’m moving.


    But Thompson and Kovaleff seem intent on maintaining Riverside as an attractive shortcut when the West Side Highway is congested. “It may not supposed to be [a commuter route],” Kovaleff said, “but the fact of the matter is that it is.

    This Kovaleff guy should be fired. Or at least ashamed. This is YOUR neighborhood. This is your home. And you’re A-Ok with people treating it as a “thoroughfare”. WTF?!?! This is your home. It’s not an expressway — why oh why would you be ok with volunteering your neighborhood for outsiders to speed through?!? That’s what I hated about the LES — you have Clinton street, which is an exit ramp for the WillyB, and you’ve got Delancey, which is a giant f- you to the neighborhood. UWS is actually nice and somewhat peaceful.

    My old roommate was hit by a car on 79th and Riverside while jogging around 2006. Car was going 30, compound leg fracture, she flew out of her shoes — if her dad wasn’t a cardiologist (i.e. good health insurance with connections), she might have permanent disfigurations and disabilities. Instead, she was very lucky to make a full recovery.

    EDIT: Sorry for the rage. I’ve been trying to ride to NJ more frequently for long rides, since, laps at Central Park (I’m not a racer, I just like the exercise), is an invitation for a running red light ticket — and taking the Greenway up, especially in decent weather, is just incredibly crowded — So Riverside Drive is perfect — not too busy, somewhat residential and lots of trees — it’s a pleasand ride notwithstanding the couple areas where its’ like a freeway. And even here, where DOT is trying to do the right thing, we get idiotic CB members unwilling to be team players, because they don’t want any delays in driving to their summer house in VT. Well, F— You! I don’t own a summer house. I don’t even own a car (though I zip). My R&R consists of me hopping on my bike and getting on to NJ 9W to Nyack or what not. I don’t want to have to zip car to Strictly Bikes in NJ, and then commence my ride. So, by making RSD unsafe, he’s increasing the liklihood that I’ll have to zip car it instead of riding my bike. I hate these people.

    Can we replace all the UWS CB members with merit scholarship students from Barnard, CUNY and Columbia please?

  • If a community board member preferred bottled water to tap, would DEP let that person’s behavior influence the design and placement of a new water tunnel?

  • bggb

    There is something tragically perfect about a community board member using “Friday trips to Vermont” as a reason to not make roads safer for pedestrians.

  • WalkingNPR

    “If people are gonna speed, whether it’s one lane in each direction, or two lanes in each direction, they’re gonna press down on the accelerator,” Kovaleff said.

    Scientifically wrong, but don’t let that stop you, Kovaleff.

    Hey, if people are gonna shoot people, they’re gonna press the trigger. Whaddaya gonna do?

  • Maggie

    Bitter chuckle here: I’m always wishing there was train service from NYC to Manchester or Bennington. They’re about an hour drive from Albany, but the train station car rental closes at 2 on Sundays. Or they’re a great long hilly bike ride from Albany, but I’m still not sure bikes are allowed on those Amtraks.

  • BBnet3000

    If CBs had any role in the water tunnels we’d all have cholera or wouldn’t live in the city at all.

  • JK

    Public to Mark Levine and Gale Brewer: Help! Come on now, was this said with a straight face? “We need wide roads to keep car traffic flowing to reduce asthma?”

  • Uptown

    For people commuting after dark above ~145th street on the West Side, riverside is the best option for biking. The bike path is shady and poorly maintained, and the St. Nick path has limited options for crossing westward.

    The riverside viaduct and the area around Grant’s Tomb are a speedway. The sections between 135th and the viaduct just north of the cemetery are generally fine (although hardly relaxing) for riding, but drivers going 45-55 mph on the viaduct and tomb area are routine. The design of the road in there mimics a highway and drivers react accordingly.

  • JK

    My wife bike commutes across the 125th viaduct everyday. I find it nauseating that Gale Brewer and Mark Levine continue to reappoint Ted Kovaloff, a guy who says things like: “And, you know, I don’t really care if people go 50 miles an hour on the viaduct.”

  • r

    My guess is that guys like Ted Kovaloff care an awful lot about whether or not your wife obeys all traffic laws when she bikes. Funny how going 20+ mph over the speed limit in a car doesn’t warrant the same concern.

  • Bluewnderpwrmlk96

    NYCDOT should not forget that community boards are advisory and should not be dissuaded by their rhetoric. It is the role, let alone the duty, of the NYCDOT to uphold a Vision Zero mission statement by implementing the safest traffic designs possible, taking in mind vulnerable road users, incorporating alternative means of transportation into designs, and factoring in err in motorist behavior.

    Kovaleff said. “And, you know, I don’t really care if people go 50 miles an hour on the viaduct.”

    Now, if that statement isn’t the exact opposite of Vision Zero…

  • JudenChino

    The design of the road in there mimics a highway and drivers react accordingly.

    Egg-fucking-xactly. People respond to design. In fact, I’d venture to say that a properly “dieted” Riverside Drive, could actually be that “bucolic” and peaceful parkway experience that Moses was all about (but at 25mph). You’ve got trees, it’s got some curves, have some bike lanes, traffic generally moves well (and would continue to do so).

  • qrt145

    If you design it so that it’s no longer an enticing alternative to the highway, people won’t use it as an alternative to the highway.

  • NYer

    So, here we have a prominent Community Board member who is encouraging motorists to speed, break the law and endanger his community, who is clearly working in opposition to one of the city’s major policy initiatives, Vision Zero, and whose policy views are based mainly on an apparent desire to facilitate speedy car trips to Vermont.

    It goes without saying that this guy is not working in the interests of the neighborhood and he should not be reappointed to the Community Board. But why aren’t Gale Brewer and Mark Levine moving to remove him from the Community Board IMMEDIATELY? What an embarrassment.

    If Gale Brewer thinks that she won’t be held accountable for this crap come next election, she is very wrong.

  • Kevin Love

    Yes, what Mark Levine and Gale Brewer said was profoundly disturbing. To the best approximation that I have been able to determine:

    1,421 people in New York City are poisoned and killed by motor vehicle drivers every year.

    5,491 people in New York City are poisoned every year by motor vehicle drivers and injured so seriously that they have to be hospitalized.

    Children in New York City experience 3,876 acute bronchitis episodes every year because they are poisoned by motorists.

    Children in New York City experience 219,640 asthma symptom days every year because they are poisoned by motorists.

    Costs of people being poisoned by motorists in New York City is approximately $7.4 billion per year.

    There are also significant issues with motorists crushing and killing people.

    Here is a video of a 4-lane urban road that was tamed and made for people, not cars. New York deserves no less. See:


  • Joe R.

    Get rid of the parking lane, substitute a bike lane protected by jersey barriers. That same jersey barrier also protects people walking on the sidewalk. Problem solved without reducing traffic lanes or asking drivers to slow to <50 mph. Oh wait, but that means no parking? Yep, you can't have your cake and eat it, too. Don't want to give up two lanes each way or high speeds, then you have to lose the parking. That parking isn't really convenient to anything, anyhow. It's now mostly free resident car storage which can be put to far better use.

  • r

    Especially since there are no businesses or residences on the viaduct. It’s very hard for anyone to argue that the life of this stretch of road depends on long-term private car storage.

  • Guest

    There are a few things that should be grounds for immediate dismissal from a community board and one of them is condoning law-breaking behavior that is proven to kill.

  • roguebagel

    I lived at the end of that stretch of the bridge for over a year and it was the most dangerous and nerve racking part of my commute. The lanes actually widen at a corner before the bridge, and enough (not all) people speed up to 40-50mph. I would regularly take the entire lane and get honked, etc. but it was my life on the line if some jackass from Westchester or New Jersey tried to side swipe me within 2 feet of my life.

    And inevitably, I would catch up to all the speeding traffic at the next stop light anyways.

  • Yeah, I loved that, I mean, they’re gonna speed, they’ll press the accelerator, whether or not there’s a car in front of them…well, I guess Kovaleff gets in a lot of rear-ending accidents.

  • Joe R.

    It kind of just shows how out of touch these people really are. Let’s keep a really dangerous street intact just so me and a minority of my friends can drive to Vermont on weekends. Never mind that a supermajority of his constituents don’t even own cars, let alone drive them to Vermont regularly.

    I have a better suggestion-resign from the community board, and since he loves Vermont so much he would rather spend weekends there, move there permanently. Encourage all his friends who do the weekend drive to (insert state of your choice) to do likewise. It’ll be a much nicer city if people like these go.

  • Joe R.

    Pretty much my experience as well when a bunch of cars zoom past me on an open stretch of road. I hit the next light just as it’s flipping to green. All the idiots in cars gun it just so they can slam on the brakes at the next red light while I catch up to them again. Hint to drivers-average speed also includes all that time you spent sitting at red lights completely stopped. You’re not getting where you’re going any faster by accelerating to 50 if you have a red light four blocks down. That’s why the guy doing ~20 mph on his bike keeps catching up to you at every light (and also why he rarely needs to stop). He’s actually noticing what the lights are doing-you aren’t. All these morons are doing is wasting gas, putting wear and tear on their drivetrains/brakes.

  • j4ys0n

    I ride my bike on this stretch pretty often. It’s definitely not very safe. I even had a guy pull up to me once and tell me I was crazy for riding on the highway. That’s not a highway! No one goes the speed limit here.

  • ahwr

    No. Leave the parking. The 79% of cars that speed on the viaduct don’t slow down when they get off. Getting rid of the second travel lane to calm the road is more important than your quixotic quest to ban parking.

  • qrt145

    Another benefit of getting rid of parking would be a much reduced amount of broken car window glass on the road and on the sidewalk.

  • Joe R.

    Just on principal the parking there should go. It’s not near anything, hence people can’t give the usual excuses for keeping it. It most likely just serves as long-term car storage for the locals, encouraging more car ownership and more driving. Get rid of it in order to discourage car ownership in the area, which in turn might mean less speeding traffic there. Also get rid of it on the principal that city streets shouldn’t be used for storing private property. Or if they are, then let people store other things besides cars there. I’ll be all too happy to stick a storage container in the parking spot in front of my house, for example. No uglier than cars, and at least it’s not a dooring hazard to cyclists. In fact, the dooring issue is the reason why we don’t want curbside parking there (or anywhere else for that matter).

    If the long term goal is to ban as much curbside parking as possible, we have to start with low-hanging fruit like this-namely parking which is so far removed from residences or businesses that nobody can really put forth a rational objection to its removal. I’ll bet if you looked at how often those cars get used, it would be very seldom. They probably belong to locals who use them once or twice a month for out of town trips. Those same people would likely not even have these cars if they couldn’t park them there. That’s why you get rid of curbside parking-to persuade the many infrequent car users in this city to just not have a car. The end result is better lines of sight at intersections, less traffic, far less street delays due to people looking for parking, or actually parking. Not to mention eliminating the aforementioned dooring hazard to cyclists. Other than “some people want it”, I can’t think of any rationale for allowing curbside parking. Hey, some people want to not pay taxes, too, but we’re not about to start allowing that. The city would function much better with no curbside parking. Businesses or individuals for whom private car parking was important would be willing to pay market rates for off-street parking. Those who don’t or won’t, well, I guess the parking wasn’t that important to them after all. Rather, it was more like a perk-nice to have, but only if I don’t pay for it.

    If you want to slow speeding cars AFTER they leave the viaduct, all sorts of solutions to that. My favorite would be bollards in between the traffic lanes (which incidentally would also prevent obnoxious lane jockeying which is even more dangerous to cyclists than speeding).

  • walks bikes drives

    But those of us who own a car and use it once or twice a month, as you mention, are neither adding to traffic or adding to the pollution, since we use them infrequently. I use my car when public transportation or cycling is not feasible. Otherwise, my car sits there and doesnt hurt anyone. I am all for losing a parking space here and there for safety, even several here and there. But your argument about the storage of cars, frankly, I find obsurd. I agree that parking should not be free, and that permits should be required with a fee attached. But your overall belief against curb side parking, I’ll never agree with. Frankly, as a pedestrian, I feel safer with 4000lbs of steel between me and moving vehicles than on a street without parking.

  • KillMoto

    “All these morons are doing is wasting gas, putting wear and tear on their drivetrains/brakes.”

    True that. But some of them are rushing to the red light so they can read and send text messages.

  • Mark Walker

    I should probably note, since no one else has, that a vast stretch of lower RSD already has two traffic lanes plus parking on both sides, in the 70s, 80s, and the 90s where I live. So converting to that configuration farther up really should not be much of a conceptual stretch. 25 (or even 20) mph would be welcome, given the many peds crossing into the park.

  • Joe R.

    Here are the reasons why I feel curbside parking is an awful, awful, really, really awful concept:

    1) Parked cars are an eyesore. That alone is enough of a reason to not allow it.

    2) In order to parallel park, you have to stop dead and then go into reverse. In other words, assuming a 30 mph speed limit, the differential speed of a parking car from traffic can be upwards of 30 mph. If that isn’t about the most dangerous thing possible then I don’t know what is. I’ve had more close calls with cars pulling into and out of parking spots than with anything else. Parking cars also impede smooth traffic flow.

    3) Parked cars create an ever present dooring hazard to cyclists. Yes, I know all about avoiding the door zone except often you can’t. For instance, you might be stuck on a street with traffic going too aggressively to take the lane but there’s not enough room in the parking lane to get out of the door zone.

    4) Parked cars interfere with snow removal. Without parked cars, plowed snow could be pushed into the nearest sewer or otherwise piled where it doesn’t block crosswalks. With parked cars often the plowed snow ends up in hills in front of crosswalks.

    5) If people can store private property like cars by the curb, then in fairness to those who pay taxes but don’t own cars you should also allow storage of other types of private property.

    6) Curbside parking increases the supply of available parking which in turn encourages more car ownership. This is true whether you charge for it or not. I’ve found many car owners are illogical, in that they’ll spend far more to keep a car than it’s worth. Therefore, even paying for parking might not be enough to discourage car ownership. Outright eliminating parking on the other hand would.

    As to those who use car infrequently, while it’s true you’re hardly adding to traffic or pollution, you are hurting the city’s economy. From an accounting standpoint owning an expensive asset which is seldom used is a highly inefficient use of that asset. It would make more sense to rent a car the rare times you need it. And that money spent on the car ends up not being put into other economic activities which might benefit the city more.

    Frankly, as a pedestrian, I feel safer with 4000lbs of steel between me and moving vehicles than on a street without parking.

    The fact that you feel you need protection from moving vehicles while on a sidewalk speaks volumes as to the horridly low standards for driver training (and if anything makes the case for a lot lower levels of car ownership/driver licensing). No way, no how should a motor vehicle properly driven ever end up on a sidewalk, even in the absence of a row of parked cars to block it. If one does, then it should be grounds for immediate, permanent revocation of the driver’s license, and forfeiture of the vehicle being driven. Besides that, if you eliminate parking, the space would most likely be used for a bus lane or bike lane. In either case, particularly a bike lane, you would want a strong physical barrier between it and motor traffic lanes. That barrier would serve the same purpose the row of parked cars does now.

  • Simon Phearson

    If you’re parking your car on the street and not driving it except for once or twice a month, you are breaking the law – city ordinances prohibit storing your car on the street for more than a week at a time.

    I don’t understand why curbside parking exists anywhere. If a business wants a place for its customers to park, let them build it! If an apartment building wants places for its residents to park, let them build it! Just think how many traveling lanes we could have, if we took out the parking lanes that are on virtually every street.

  • walks bikes drives

    But alas, it is not breaking the law because I do move it, several times per week – but just across the street. Alternate Side Parking.

    But why would we want so many travel lanes? That increases speed. And having cars parked on the side is effectively a road diet of sorts. But again, I am in firm agreement there is room for improvement.

  • Sean Kelliher

    You’re right. Parked cars do provide a road diet, but it is a not very attractive and not very productive use of space.

    We’re coming from the perspective that the space can only be used for either vehicular travel or parking. There are other uses though to consider. Here are a few examples –

    The space could be repurposed for a wider sidewalk or bike lane. Thinking broader – we could have a row of trees to shade buildings, clean the air, increase property values, and provide spots for people to rest. It could be a play area for children to get exercise close to home; or space for vendors that would provide jobs and generate tax revenue.

  • Bobberooni

    A long as there are two lanes going through the intersection,a road diet on the viaduct will make no difference in traffic capacity. Road capacity increases with decreasing speed, all the way down to 20mph. The fact that there is so much speeding is evidence that the viaduct is way under capacity. Channeling the cars into one lane will make it far safer for anyone walking, biking or parking there.

  • Bobberooni

    The viaduct is a last ditch parking spot for people willing to walk twenty minutes in an area where jobs pay a fraction of what they do in midtown and it’s served by only one local train. Give em a break, people are getting exercise.

  • Bobberooni

    Trees on the viaduct? Do you know what road you’re talking about? And how will that increase property values for the numerous homes built along that street? This isn’t the High Line…

    Sorry, I think the best uses for that space are travel (bike & car), and parking.

  • Bobberooni

    > 1) Parked cars are an eyesore. That alone is enough
    > of a reason to not allow it.

    The same “logic” is used all too frequently against bike parking and CitiBike. Enough is enough.

    > In other words, assuming a 30 mph speed limit,
    > the differential speed of a parking car from traffic
    > can be upwards of 30 mph.

    Yes, it’s now 31mph. And the fact that someone is backing up encourages everyone to slow down, which is good.

    > Frankly, as a pedestrian, I feel safer with 4000lbs of
    > steel between me and moving vehicles than on a
    > street without parking.

    The parked cars also prevent you from getting splashed on a rainy day.

  • Bobberooni

    If you’re going to do that, you need to also design the highway with adequate entrance ramp capacity. If you’re trying to get to the GWB from Morningside Heights, getting on the Henry Hudson at 125 St. can be a huge bottleneck. Among other things, it involves a crazy left turn with full of people trying to illegally cut in front of you.

  • Bobberooni

    Riverside drive may be an alternative to the Greenway if you’re coming from midtwown. But from Morningside Heights it’s the only way to get to the GWB without major hills. For those of us who (used to) bike-commute there from NJ, that’s important.

  • andrelot

    This assertion

    ” Road capacity increases with decreasing speed, all the way down to 20mph”

    is false in the sense that optimum road throughput is contingent on geometry and other design features.

    Controlled-access highways with standard design have a peak capacity at around 55-58mph.

  • Joe R.

    On the speed differential, think of assholes who put it in reverse at 15 or 20 mph to grab a parking spot which was just vacated behind them. I’ve had close calls with people like that. Then you have your run of the mill “I’m looking for a spot” driver who is going at 10 or 15 mph, stopping or slowing frequently when they see someone they think may be vacating a spot. It’s f-ing annoying as hell to be behind a jerk like that. It’s one thing to slow the general speed of free flowing traffic from 40 or 50 mph down to 20 to 30 mph. That’s good. It’s quite another to add the element of unpredictability that people parking or looking for parking cause. Public roads are thoroughfares for transportation. As such, you generally want traffic lanes to be moving at design speed all the time unless there’s a good reason for them not to be (i.e. a red light). Parking or looking for parking causes unpredictability, which in turn causes collisions and gridlock. On some streets half the traffic is people looking for parking.

    As for the aesthetic argument, yes, I’m 100% OK when people use that as an argument against bike parking, too. Parked bikes don’t look a whole lot better than parked cars but in their defense a bike rack doesn’t block lines of sight at intersections. Also, you can park a dozen bikes in the space of one car, meaning the street will look much better if you replaced car parking with bike parking on a 1 to 1 ratio. Your typical 250′ city block which can now accommodate maybe 20 parked cars on both sides can serve the same number of people with one bike rack maybe 30 feet long. It still may be ugly, but it leaves most of the street free for other uses. Also, bikes parking or unparking don’t cause all the aforementioned traffic issues. And then you have the fact that many businesses can actually easily accommodate a small number of bikes inside the store just by putting up a small bike rack. Can’t do that at all with cars, barring of course an expensive parking garage on site. Bottom line-parked bikes are lot easier to deal with than parked cars, both in terms of aesthetics and cost.

  • Joe R.

    I think he means absolute peak. If we assume cars follow each other at such speed that they can stop if the car in front suddenly stops dead, then that implies following distances of ~160 feet at 55 mph but only 20 feet at 20 mph (I’m using the same deceleration rate, 0.63g, for both calculations). Add in 20 feet for car length. This gives us 1613 cars/hour at 55 mph but 2640 cars/hour at 20 mph. If you want to add 0.5 second reaction time to the calculations then we get 1318 cars/hour at 55 mph and 1931 cars/hour at 20 mph.

    That said, unless there’s a really good reason to slow cars down to 20 mph, like many vulnerable users who can’t be totally physically separated, it makes more sense to go with higher design speeds. Modern cars are actually most efficient in the 45 to 55 mph speed range. The exception is EVs whose efficiency peaks at ~5 mph (if we ignore heating/cooling power in the passenger compartment). Moreover, in the interests of transportation efficiency, combined with modern car design, it seems 75 to 100 mph is probably most optimal if you have total physical separation,. Obviously this means limited access highways, not urban surface streets. Anyway, the larger point is capacities per lane continue to increase as speed decreases, at least down to about 20 mph. Below 20 mph they decrease. Besides that, there are few safety benefits slowing motor traffic to less than about 20 mph. At 20 mph it’s possible to avoid most collisions with vulnerable users, or to brake down to a low enough speed that a collision is highly unlikely to cause injury. That’s not so if we allow 30 to 50 mph speeds on urban surface streets.

  • Brill Cream

    because most apartment buildings in Manhattan were built before car ownership was so widespread, and when El’s and trams made it easier to get around the city.

  • Brill Cream

    The traffic on Riverside Drive is a direct result of the congestion on the West Side Hiway, which is caused by poor exit ramps to the GW, the Cross Bronx and the Deegan. Which means that if buses or cabs – as well as private cars – and ambulances and fire trucks need to get up and downtown quickly, some thought must be given to how Riverside remains traffic free. None of this lives in isolation.


DOT Weakened Riverside Drive Plan to Appease Manhattan CB 9 [Updated]

DOT watered down and delayed an already half-hearted plan to make Riverside Drive safer for walking in deference to opposition from Manhattan Community Board 9. Riverside is a neighborhood street, lined by apartment buildings and parks. It also ranks in the top third of Manhattan streets in terms of the number of collisions, which is supposed to mean […]