A diet you'll actually enjoy

A diet you'll actually enjoy

To some, the word "diet" has four letters. But for city planners, highway engineers and regular folks who just want expanded transportation options, a road diet can be a blessing and not a curse. 

In simple terms, a road diet takes a road's vehicular cross-section - meaning the number of lanes - and revises it to better accommodate the needs of all road users, according to Jason Salley, the Geometric Studies Unit Head for IDOT's District 1.  

"Typically, road diets involve converting an existing four-lane road with two travel lanes in each direction and no median into a road with one travel lane in each direction and a center turn lane," Salley said. "This can reduce the number of rear-end and left-turn crashes, thanks to the dedicated turn lane, as well as give pedestrians fewer lanes to cross." 

A road diet also gives planners and engineers space for additional transportation options and other safety features, such as expanded bicycle and pedestrian accommodations or dedicated bus lanes. They also can be achieved simply and relatively cheaply in most situations without the need for a complete road reconstruction, Salley said. 

The city of Batavia in Kane County adopted a road diet for two sections of Batavia Avenue (Illinois 31), which showed off its new configuration in late 2024. Construction took just a few weeks because all that was needed was resurfacing with new pavement markings.   

Similar conversions took place in recent years in East Dubuque and Rock Island, with the concept gaining popularity throughout the state. 

But why, though? 

At its core, a road diet is a tool to increase safety for all road users - cars and trucks, buses, walkers and rollers. The city of Batavia had been considering one for Illinois 31 for some time but was moved to act in 2023 after a driver struck and killed a bicyclist and another driver struck and seriously injured a child. 

While the city did not install bike lanes with the road diet, there haven't been any crashes involving bicycles or pedestrians since the new configuration opened. 

The city of Springfield in Sangamon County has reconfigured parts of three streets in recent years for road diets, with the most recent debuting last September. In each case, the city monitored relevant data, according to T.J. Heavisides of the city's Office of Public Works. 

"The city is looking at streets that have higher-than-normal average and 85% speeds, certain crash patterns and relatively low traffic volume based on the number of lanes," Heavisides said.  

The newest one, on a one-way stretch of Seventh Street downtown, was chosen because traffic volumes were below the need for three through lanes, according to Heavisides. And on a section of Walnut Street on the city's near west side, a road diet was prescribed as a countermeasure to the specific type of crashes that were occurring. 

"When we identify these items, we may reach out to IDOT for support and funding," he said. 

That funding usually comes from IDOT's Highway Safety Improvement Program, according to District 1's Salley. HSIP is a core federal program that aims to reduce serious and fatal injury crashes through proven, data-driven countermeasures. 

Fad diet? 

Opponents may scoff at road diets as just being transportation planning's current latest trend, but a growing body of evidence shows the benefits of reducing traffic lanes. 

One such study involved a section of Edgewater Drive in Orlando, Fla., where the road was redesigned from four through lanes to two with a center turn lane and bike lanes on each side of the road. After the new configuration opened, data were collected on eight criteria for success, such as a reduction in crashes, increase in pedestrian/bicycle volumes, reduction of speeding and more.

The data exceeded benchmarks on all eight points, including a 34% reduction in crashes and a 68% reduction in injury rate. Cycle and pedestrian counts increased 30% and 23%, respectively. 

Here in Illinois, road diets first began to be implemented about 15 years ago, with the first one in the state system installed in Chicago Heights, according to Jonathan Lloyd, a traffic program engineer in District 1.

"As we monitored crash performance of existing road diets and as their use became more widespread, we found that in the right situations, they could notably reduce both the frequency and severity of crashes," Lloyd said. "They also provided the opportunity for additional transportation options, so we began to expand their use."

Another example is 47th Street in Western Springs.

"The community came to us with their concerns and inquired what could be done to improve the road. There were crashes and speeding, and aggressive driving was common," Lloyd said. 

"So we took a look and analyzed the data - including for crashes and traffic volume - and said 'yes, we could probably do a road diet here,' and it could address both the crashes we found and the community's concerns."

That project currently is in early planning stages, with a dozen more in District 1, which covers Cook and the collar counties, also in various stages of planning and implementation.

 Also driving increased adoption of road diets is the simple fact the data show that they work. Lloyd said that the more obvious options were chosen to show the public their potential.

"When you are dealing with something that is new or different, the public can often be wary," Lloyd said. "We try to focus first on locations where we know they will work so we can prove to people that they can be beneficial. It helps us build trust and confidence.

"We saw pushback from our first roundabouts, and now we actually hear a lot of people asking us to install them," Lloyd said.