Tag Archives: traffic

Definitions: Induced Demand

12 Aug

This is the first in an occasional series of posts that examine some of the terminology and concepts we use in transportation advocacy. Some of the terms are industry jargon and some of the concepts challenge conventional wisdom. Our goal is to help educate the public so we can have informed engagement with our civic agencies. Today we are tackling the concept of induced demand.

“The traffic is so bad, we need another lane.” 

This is a common refrain by drivers and supported by the way traffic engineers have built our cities. We frequently see two or three lane streets widened to four or five lane roads. We have seen this most recently in the http://www.keepomahamoving.com/ work in widening several roads in west Omaha. It is a logical assumption that more lanes would mean less congestion until we look at the induced demand of those new lanes.

Why we drive

In a congested system, people often choose not to drive during the busiest times of day if they can avoid it. They might wait until a less busy time, use alternative routes, or simply not make certain trips. Aside from the trips that must be made, people’s willingness to drive is determined by their tolerance for traffic. 

Effects of a wider road

Initially, a wider road will decrease travel times and reduce traffic. Since there is less congestion, more people are willing to drive at peak times. This will continue until we reach the old equilibrium point … the traffic will be the same as it was before the widening. 

People also drive much faster on wider roads, ignoring the speed limits. This is especially true at non-peak hours when the road has far too much open space, allowing people to jockey lane-to-lane.

“But more people are traveling, isn’t it still an improvement?”

No. City streets are part of a much larger system. For example, a newly widened road might encourage people to live in a home further away from their job. These new drivers to an area help build the congestion. People are more willing to make unnecessary trips, or drive when biking or public transit would have also been good options.

Effects of all those lanes

The city is responsible for maintaining all of the roads. This past winter’s potholes showed just how far behind the city is in maintaining the roads we already have. Adding lanes only increases the city’s future maintenance liability. It also encourages sprawl development pattern over in-fill development, and makes our roads less safe, especially for people who are not in cars either by choice or circumstance.

Coffee Chat with Keep Kids Alive Drive 25

18 Jul


Tom Everson, Executive Director of Keep Kids Alive Drive 25, intentionally uses the phrase “traffic incident” rather than “traffic accident.” He chooses “incident” over “accident” because 94% of traffic-related deaths are attributed to behavior.

At the June Coffee Chat, Tom shared that the main objective of Keep Kids Alive Drive 25 (KKAD25) is to make streets safer for everyone, starting in neighborhoods. KKAD25 implements their mission by educating and engaging the public on road safety. Perhaps their most well-known approach to this objective is their catchy and important safety signs distributed around the world.  Continue reading

Omaha Reflects National Trend in Leveling of VMT

26 Mar

The Metropolitan Area Planning Agency (MAPA) just released its Traffic Growth, Top Intersection, and Top Interchange reports for 2012.

cover-octnov-06-72MAPA does this report every two years by aggregating traffic count data from local jurisdictions, the Nebraska Department of Roads, and the Iowa Department of Transportation. The Top Intersection and Top Interchange reports aggregate counts at locations throughout the metro to identify and rank the intersections moving the highest traffic volumes. The Traffic Growth Report aims to provide a snapshot of the geographic distribution of Vehicle Miles Traveled (VMT) in the region. Additionally, this report compares the current figures to previous versions of the report to identify trends within each area of the region.

Overall, the Traffic Growth Report shows that VMT has essentially stabilized in the region over the last decade. This trend mirrors the larger national trend that shows a similar flattening of traffic growth. More strikingly, as the population continues to grow, VMT on a national level has decreased in recent years.

However, nationally these trends have not slowed the development and implementation of roadway widening. Locally, MAPA Executive Director, Greg Youell, noted in an interview about the reports that these new figures serve as justification for additional roadway widening in West Omaha and suburban parts of Sarpy County. While systematic road widenings are the status quo, these types of projects have been shown to “induce demand” and generate more vehicle trips– often making congestion issues even worse. The data, as well as findings from MAPA’s Heartland 2050 efforts, don’t seem to align with a call for more road widening. Nor does it align with the goals of the Omaha Master Plan as we’ve recently noted.

As a result of this “capacity-oriented” approach, many communities are now faced with overbuilt roadway networks and extraordinarily high maintenance costs. This has lead Omaha and other communities to consider “road diets” and other approaches to undo past capacity-enhancement projects as well as better accommodate people who walk, bike, or use transit. These types of complete streets have many other benefits, including reducing roadway costs, enhancing property values and economic development, and improving safety for all users.

Do we want to keep pouring more and more money into a transportation system that is increasingly costly, unsustainable and serving only those who drive? Or would we prefer a system that reduces long-term costs and enables all of us to get around no matter which mode we choose?

Please contact MAPA’s Executive Director, Greg Youell, and tell him that the data from the traffic study shows we need investments in road design that matches current trends and regional and local government policies and plans, and which enable safe and convenient transportation choices for everyone. While you’re at it, contact the Mayor and City Council members to tell them the same.