Creston considers highway lane conversion

The City of Creston recently announced they are considering converting the highways from four lanes to three lanes. These types of conversions can provide benefits to the community as access to businesses becoming easier, the roads and areas surrounding the safer for pedestrians and bicyclists, and result in fewer vehicle accidents.

Conversion of highways of this nature are generally done on roads that have a daily traffic count of less than 18,000 vehicles, while the busiest areas of Creston reach approximately 10,000 vehicles, said Chris Poole, Iowa Department of Transportation safety programs engineer.

"Our experience has shown that traffic volume does not go down," said Poole.

In converting a 4-lane highway to a 3-lane highway changes are made by restriping, or painting, the lanes differently than they currently are. This is usually done when another project is being done, such as resurfacing of roads, for example. Poole said when restriping of lanes is done along with a resurfacing project there is no cost.

Most highways have 11-foot wide lanes. Projects like this can widen lanes slightly to 12 feet. In addition, the excess on either side can become a shoulder area or be used for other purposes such as bike lanes.

Some cities want to encourage bike traffic so they mark excess space as a dedicated bike lane, said Poole. While it doesn't happen often on the state highway system it is commonly done on city streets, said Poole.

Poole said the roads where these conversions have taken place are safer for pedestrians because less lanes exist for pedestrians to cross, extra shoulder space means the lanes of traffic are further from the sidewalks and less time is spent in lanes with traffic while crossing the road.

“The distance that a pedestrian would be exposed to traffic is reduced and it makes crossing a lot easier,“ said Poole. “The traffic lane is now typically located further from the sidewalk further from where the pedestrians are located so there’s just an increased sense of security from that and I think it lends itself to encouraging more walking.”

One question posed by emergency first responders is whether response times to incidents change.

Poole said the 3-lane configuration is flexible and the center lane is often open so first responders can use this lane when necessary. Unlike 4-lane highways where fire truck, for example, is not allowed to cross the center double yellow lines.

In rural Iowa, the conversion does not impact farm equipment operators who often use the roads.

"The width of the pavement doesn't change so there is just as much room out there now as there would be after the project," said Poole.

Undivided 4-lane highways have increased rates of vehicle accidents when motorists attempt left-hand turns and collide with other vehicles.

"Those are a pretty violent crash," said Poole. "Those are the types of crashes that just pretty much go away when you convert to three lanes."

Poole said 4-lane to 3-lane conversions produce a 50 percent reduction in car crashes overall with a 70 percent reduction in left turn crashes.