July 26


7 Solutions for Curbing Traffic Demand

By Mike Spack

July 26, 2016

carpool, mitigation, supply and demand, traffic impact study, Travel Demand Management Plan, Trip Generation

By Bryant Ficek, PE, PTOE

For many projects, the end result of the traffic engineering work is mitigation in the form of an added turn lane, a new traffic signal, or other types of geometric and traffic control improvements. Basically, you look for ways to safely increase the ability to accommodate more vehicles. We call this the supply side. And while that needs to be considered, don’t forget about its opposite – the demand side.

If the supply focuses on the capacity of the roadway network, then the demand focuses on the trip generation. As one would expect, if you are able to lower the vehicle trips, then you need less infrastructure to accommodate it.

Here are seven methods we consider when examining the demand side of the equation (in no particular order):

  1. Connections to Alternative Modes of Travel. In this day and age, considering pedestrian, bicycle, and transit facilities should be a no-brainer. Does the development provide sidewalks/trails to the surrounding network? Is bicycle parking provided? Does the apartment lobby provide information on transit routes? Besides just providing these facilities, they also need to be safe and convenient. A bike rack behind the building, next to the garbage, and without lighting will not get used by most people.
  2. Peak Period Delivery Restrictions. Deliveries are generally made by trucks. The bigger the development, the larger the trucks that could be expected. Trucks take up significantly more room when stacked at a red light. Some trucks may need to complete right turns from the through lane, taking up two lanes at once. Trucks also have slower acceleration times and take longer to slow down/stop. With all these characteristics, removing or reducing the percentage of trucks during the peak periods can help keep satisfactory operations. Often, truck drivers don’t want to drive in congestion anyway.
  3. Peak Period Parking Restrictions. This can be helpful in two ways. If on-street parking is prohibited during the peaks, then an extra lane for through traffic may be available. In addition, if drivers know parking is reduced during the peaks, then they are more likely to choose non-peak times to go to a development.
  4. Paid Parking/Preferred Parking Spots. When putting a cost on parking, many people will look at how to avoid that fee. That includes car-pooling or using alternative modes. Preferred parking spots can also incentivize people, such as labeling the spaces close to the front door as car-pool only.
  5. Movement Restrictions. Traffic through an intersection operates better if conflicting movements are reduced. This could include a permanent change to 3/4-access or right-in/right-out only or signing peak period restrictions. Just be sure that the adjacent intersections are able to accommodate the consolidation of turning movements.
  6. Alternative Incentives. One alternative strategy is allowing flexible work hours so employees are able to travel outside of the peak periods. Another is providing financial motivation, such as a reduction in health care cost for biking/walking to work or free/reduced transit passes.
  7. Reduce the Development Size. This is the demand side weapon of last resort. No developer wants to hear this suggestion and may be against other goals of increasing density. However, a smaller footprint will have less traffic.

In Minnesota and other areas, these strategies are often formalized in Travel Demand Management Plan (TDMP). These plans examine all modes of travel and provide a list of strategies to lower the number of single-occupancy vehicles going to and from a development.

Whether as part of TDMP or included in a regular Traffic Impact Study (TIS), we have considered and used all of these tactics at one time or another to improve overall traffic operations or eliminate the need for a roadway improvement. Recommending one or more of these strategies can generate push-back from the developer and/or the overseeing agency depending upon many factors. But we believe that examining both the supply and demand is the best approach to help provide safe travel for all.

Bryant Ficke Bio

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Mike Spack

My mission is to help traffic engineers, transportation planners, and other transportation professionals improve our world.

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