Learning to Love Your Traffic Engineer – Speed and Volume

Wednesday, November 20 by JerryFoster

us-vmt-projectionsUnlike residents, our traffic engineers prioritize speed and volume over safety and low cost – why? It’s how they were trained.

We’re long past the era where roads provide orders-of-magnitude improvement, e.g. from walking to motoring, but policy still encourages speeding, e.g., engineers design for 5-10mph over posted speed, so 74% of drivers on Rt 1 in Plainsboro exceeded the speed limit recently.

Going faster means getting there faster, right? Only if you’re on the mythical open road – in densely populated New Jersey, we have traffic.

Speed can work against getting there faster in traffic, since cars stay further apart – the best volume throughput is at 30-46mph. Improved signal coordination and speed harmonization allow people to get there faster even though they’re going slower, by delaying the onset of stop-and-go congestion.

Historically, traffic increased year after year, but in 2004 per capita volume (vehicle miles traveled) declined (!), followed in 2007 by a total volume decline as the recession took hold.  Though the Great Recession ended June 2009, total volume remains at recession levels, and per capita volume continues to slide.

Is it the end of “build it and they will come”? If so, engineers will have one more reason to change their priorities. In our next installment of Learning to Love Your Traffic Engineer we’ll look at safety.

 

 

 

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Just for Goofy Fun

Sunday, January 23 by JerryFoster


In 1950, Disney produced a cartoon short starring Goofy called “Motor Mania”, showing how a mild-mannered citizen becomes a demon driver once behind the wheel. Some things just don’t change!

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Tale of Two Engineers – One Visionary, One Recovering

Thursday, December 2 by JerryFoster

A revolution is underway in how towns are being redesigned for livability, and it’s playing out right here in West Windsor. The late Hans Monderman launched a movement for better safety without signs and signals, while in the Confessions of a Recovering Engineer, another engineer realizes that “Wider, faster, treeless roads not only ruin our public places, they kill people.”

Tom Vanderbilt, author of Traffic: Why We Drive the Way We Do (and What It Says About Us), recounts the work of the late Hans Monderman, a Dutch traffic engineer who held to a maxim: “When you treat people like idiots, they’ll behave like idiots.” In appropriate settings, he removed the signs and signals that tell drivers what to do. His goal? “I don’t want traffic behavior, I want social behavior.” His work underlies the design for the promenade in the new transit village west of the train tracks.

In Confessions of a Recovering Engineer, Charles Marohn relates his professional experience “convincing people that, when it came to their road, I knew more than they did.” Why? “I had books and books of standards to follow.” Finally, “In retrospect I understand that this was utter insanity. Wider, faster, treeless roads not only ruin our public places, they kill people.”

This realization is slow in coming to our Rt 571 Main Street design, where the state guidelines are in place but the design hasn’t taken them into consideration.

Please help the county engineers learn from the transit village engineers by supporting the WWBPA’s recommendations for Rt 571 Main Street – slower speed, medians with pedestrian refuges and a pedestrian-activated signal that stops traffic at the crossing at Sherbrooke Drive.

This redesign is our chance to make drivers comfortable with the slower speed – just posting a lower speed limit will not effectively slow traffic. Our tale of two West Windsors might have the happy ending of a pedestrian-friendly Main Street and transit village promenade, leading to higher property values for us all.

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West Windsor’s New Woonerf

Wednesday, November 24 by JerryFoster

PJ Promenade as Shared SpaceTownship Council adopted a new concept Monday night for shared streets, also called a woonerf, for the Princeton Junction Transit Village. What’s a woonerf, and how does it work?

Developed by Dutch traffic engineer Hans Monderman, a woonerf is a street where pedestrians and bicyclists share the roadway with motorists as equals.  This concept goes by a number of other names, such as Living Streets, Home Zones or shared space.

The safety of such spaces depends on extremely slow speeds and one-on-one human eye contact to negotiate movement through the space. Read about one town’s experience with removing traffic lights.

The WWBPA made several recommendations to improve the bikeability of the proposed area, including more bike parking at the Farmers Market and in residential parking structures, as well as requiring back-in diagonal parking for improved safety.

The WWBPA is confident that this plan, if built as shown in the pattern book, will be eminently walkable, and will provide those bicyclists who are comfortable in traffic with a wonderful place to stop and enjoy the amenities, like the Farmers Market. We are hopeful that motorists, bicyclists and pedestrians will embrace the new shared street and quickly learn to navigate without traditional traffic control.

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Lawrence Township Adopts Complete Streets Policy

Sunday, November 21 by JerryFoster

Lawrence Townhall

Lawrence Township Hall

On September 21, 2010 Lawrence’s Township Council passed a Complete Streets Resolution, which calls for “all public streets … to safely accommodate travel by pedestrians, bicyclists, public transit and motorized vehicles and their passengers, with special priority given to bicyclist and pedestrian safety”.

Lawrence is one of the leaders in adopting Complete Streets in New Jersey, joining the state, Monmouth County, Montclair, West Windsor, Hoboken, Red Bank and Netcong.

Mercer County Executive Brian Hughes “has directed his staff to consider context-sensitive solutions that enhance safety for all travel modes whenever the County implements an improvement”, according to a recent press release. Can a Mercer County Complete Streets Policy be far behind?

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Morning Commute

Saturday, November 13 by sandy

The WWBPA conducted another in our series “West Windsor Walks” on Monday, November 8 from 6:45 to 7:15 a.m. at the intersection of Cranbury-Wallace Roads and Route 571. As we watch the construction of a sidewalk and new travel and turn lanes on the bridge over the railroad tracks and await the addition of marked crosswalks, we continue to see conflicts with pedestrian and cars. Many people cross mid-block both across Route 571 and across Wallace Road as they look for the quickest and, what they perceive to be the safest, routes to the Princeton Junction Train Station.

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Roadways Designed for Speeding?

Friday, November 5 by JerryFoster

Cars Don't Want to Stop from 40mphAccording to NJDOT’s Smart Transportation Guidebook, many different factors come into play when choosing a desired operating speed for a roadway. From the discussion of speed:

“Desired operating speed is best explained by its relationship to three other concepts of speed: operating speed, posted speed, and design speed.

Operating speed is the speed at which a typical vehicle operates, commonly measured as the 85th percentile speed of all vehicles.

Posted speed is the legal speed limit on a roadway. It is often set without any means of self enforcement, and drivers tend to travel at what they perceive as a safe speed regardless of the posted speed. Fewer than a third of drivers go the speed limit on urban and suburban arterials.

Design speed (as defined in the AASHTO Green Book) is the speed used to determine various geometric design features, including horizontal curvature, gradient, superelevation, stopping sight distance, and, for rural highways only, lane width.

Historically, New Jersey has required the design speed to be 5 mph above posted speed for existing roadways, and 10 mph for new roads.

The greatest drawback to the existing design speed approach is that drivers usually drive as fast as they believe the road can safely accommodate.

Existing policy may thus encourage operating speeds higher than the posted speed limit and/or selected design speed in an area.

In the interest of highway safety, it is desirable to have a stronger relationship between the posted speed limit, design speed, and operating speed. Therefore, this guidebook recommends that the desired operating speed for most roadway types be the same as the design speed, and also the same as the posted speed.”

According to the Rt 571 Concept Design reviewed by county engineers in December 2009, the Main Street Princeton Junction design speed is 45mph, posted speed is 40mph, keeping the same values as exist currently.

Vehicle speed affects pedestrians’ safety in a number of different ways.

Likelihood of Collision

“Faster speeds increase the likelihood of a pedestrian being hit,” according to Federal Highway Administration’s Pedestrian and Bicycle Information Center.

Severity of Collision

If a pedestrian is hit by a vehicle traveling at 40mph, he/she has a 15% chance of survival, but if the vehicle is going 30mph, chance of survival increases to 55%, according to the Federal Highway Administration’s Pedestrian Facilities Users Guide: Providing Safety and Mobility (2002).

Crosswalk Compliance

Last, motorist compliance with yielding to pedestrians in crosswalks is significantly improved by reducing vehicle speed to below 35mph, according to the federal report Improving Pedestrian Safety at Unsignalized Crossings.

The WWBPA has requested the township to work with the county to follow the new NJDOT approach (called Context Sensitive Design) to choosing a desired operating speed, to support our emerging Main Street. NJDOT guidelines for a Community Arterial in a Suburban Center or Town Center context call for a desired operating speed of 25 – 30mph. Please support the WWBPA by contacting our officials, or write us an email at wwbikeped@gmail.com.

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Slow Down in Plainsboro

Tuesday, November 2 by silvia

Wicoff School, PlainsboroResidents around Wicoff School in Plainsboro want police to strictly enforce the 35 mph speed limit and the 25 mph limit during school hours or that the speed limits be reduced, and both the police chief and mayor say they understand. Police have issued 59 tickets in the area over the past year, or a bit more than one a week.

But here’s some insight into how hard it can be to change a speed limit and how much we tolerate breaking the speed limit: According to an an article in The Packet, a police traffic survey done this summer found that about 90% of cars were traveling at 40 mph, with the remainder traveling above 40 mph. Under New Jersey Department of Transportation’s regulations, this isn’t a problem because at least 85% of cars are traveling within 5 mph of the speed limit.

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