Roads Don’t Have to be Wider to Move More Traffic


From ancient Roman roads to the 20th Century, we assume roads have to get wider to move more traffic. However, we are helping our customers to understand that this is no longer automatically true.  As communities continue to advance and innovate, the most effective road may be different than it used to be.

Whenever engineers talk to a government agency about ways to improve a road, it is normal to get information on the number of vehicles that currently use it. The typical approach is to make sure there is enough capacity in place to handle that number of vehicles. If there isn’t, the natural tendency is to automatically start looking at what extra pavement could be added to the road to provide enough capacity. However, there is likely a better way.roads

Asking Better Questions

Over the past several years, we have started to apply better questions about roadway improvements. Things to consider include:

  • How is the volume of traffic changing over the past 10 years thru the next 20 years? Is it trending up or down?
  • If the road has more than 2 lanes, how efficiently are those lanes moving vehicles?
  • Are there a lot of left-turning or right-turning vehicles along that section of roadway? Are there already turn lanes in place?
  • Is traffic capacity controlled by existing traffic signals along the road? How efficiently are those signals moving vehicles along both intersecting roads?

These types of questions allow our team to develop a more fundamental understanding of how that portion of the road network is being used and how well it’s succeeding (or failing). When we can provide a better understanding to customers, then we can help them select better solutions.

“A ‘rightsized’ street will better serve all users. Where applied appropriately, these projects increase safety, offer more mobility, and can become a catalyst for other community re-investments. There’s also a hidden perk of less pavement to maintain, sweep, and plow.” – Mark Sherfy, P.E., PTOE

In a typical commercial corridor with driveways along both sides of the street, three lanes can actually work better than four. While intuitively folks would think “75% of the amount of pavement equals only 75% of the capacity,” reality doesn’t always match our instinct. With two lanes in each direction (four lanes in total) and a fair number of left turns along the road, the inside lane in each direction will function as a part-time left-turn lane. This means that during heavy traffic, a road might only effectively have two lanes of capacity. As an extra complication, drivers in the U.S. typically associate the left lane as being the place for faster vehicles to be. Drivers expecting to be in the “fast” lane don’t always mix well with vehicles that are stopped while waiting to make a left turn – ambulance calls, traffic citations, and insurance claims are a far-too-common result.

The Many Benefits of Getting it “Just Right”

Our approach is to understand that an existing four-lane road may function more efficiently with fewer crashes when we break it down into its fundamental demands/needs and then determine the optimum number/type of lanes that are needed.

In more than one project, we have demonstrated that traffic can move more efficiently and safely using less pavement than before. These situations are often described as “road diets.” These opportunities to reduce the amount of roadway pavement provide several benefits to communities:

  • Less pavement typically means reduced maintenance costs for communities.
  • Extra space becomes available to meet other public needs like bike lanes, wider sidewalks, room for more utilities, landscaping, street lighting, etc.
  • Space for dedicated right-turn lanes if there is a particular high-volume destination along the road.
  • More consistent vehicle speeds that can reduce air pollution and speeding.
  • Room for on-street parking in some locations, if appropriate.
  • Reducing the need to acquire additional right-of-way, avoiding extra cost to community and disrupting existing property owners along the road.
  • Shorter distances for pedestrians to cross making it safer for everyone.

Competing Needs for a Better Tomorrow

We have found that the most challenging part of these efforts to make roads “just right” is convincing the public and elected officials that such a change can actually make things better. Our ability to model different traffic conditions and show visual simulations of these options to the community is very helpful. Some communities have also considered restriping a road on a temporary basis to see how a different lane arrangement might work before committing significant funds to make permanent changes.

BHC RHODES Randy Gorton - Public Works

Randy Gorton, P.E., PTOE Project Manager

With so many competing needs for funding and public right-of-way, contact us to help you manage your traffic efficiency.

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