West Des Moines, IA

Because traffic in a city is so complex, it is almost impossible to give everyone a green light at every stop. Our goal is to reduce the total wait time for the highest number of drivers.

Here is why you may still hit a red light:

1. Busy streets get more "Green Time"

We prioritize the busiest streets to keep the most people moving. This means drivers on major roads usually get longer green lights, while drivers on smaller side streets may have to wait a little longer.

2. Many signals use sensors

Most of our signals are "smarter" and change based on real-time traffic. Sensors in the pavement detect when a car is waiting. If a lot of cars are coming from one direction, the signal will stay green longer to clear them out. Because traffic changes every minute, the timing of these lights changes too.

3. Some signals work as a team

In areas where intersections are very close together, we time them to work as a system. This allows a group of cars to travel through several lights in a row without stopping. However, this "teamwork" usually only works for the main road, meaning side-street drivers will see more red lights to keep that main group moving.

4. Balancing the wait

In the end, traffic timing is a balancing act. If we give one direction a permanent green light, every other direction would be blocked. We aim for the "minimum total delay," which means we try to make the average wait time as short as possible for everyone in the city.

The safety of our children is a top priority. While many parents ask for "Children at Play" signs to slow down traffic, studies show these signs often don't work as intended. Here is why:

1. Signs don't change driver speed

Drivers usually choose their speed based on the road itself—like how wide it is or if there are parked cars nearby. Studies show that signs alone do not slow drivers down, especially if they don't see children playing right at that moment.

2. Overuse leads to "sign blindness"

Warning signs work best for permanent hazards, like a sharp curve. Because children aren't always playing in the street, drivers begin to ignore the signs when they see them everywhere but don't see any children.

3. A false sense of security

These signs can make parents and children feel safer than they actually are. Real safety comes from education. We encourage parents to teach children that the street is never a safe place to play and that they should never assume a driver sees them.

Crossing the street at a busy intersection can be stressful. Traffic signals are timed to give you enough time to get across safely. Here is what the symbols mean:

1. The "WALK" Symbol

When the white WALK symbol is on, it is your turn to start crossing. You typically have 4 to 7 seconds to enter the street. Before you step off the curb, always look in all directions for any vehicles that might be turning.

2. The Flashing "DON’T WALK" Symbol

If the orange hand starts flashing while you are already in the street, keep going. You will have enough time to finish crossing safely.

However, if you are still on the sidewalk when the hand starts flashing, do not start crossing. There is not enough time left for you to get to the other side before the light changes.

3. The Steady "DON’T WALK" Symbol

When the orange hand stays on and is not flashing, it is not safe to be in the crosswalk. Stay on the sidewalk and wait for the next walk signal.

We set speed limits at the speed that most drivers naturally travel on a road. This speed is usually the most reasonable and safe for everyone.

1. Safety comes from consistent speeds

The safest roads are those where every car moves at roughly the same speed. If a speed limit is set too low, some drivers will follow it while others ignore it. This creates a dangerous mix of fast and slow traffic, which increases the risk of accidents. It is actually safer for everyone to move at a steady, predictable pace than to have drivers traveling at very different speeds.

2. Standard limits in Iowa

In Iowa, drivers are expected to follow these standard speeds unless a sign says otherwise:

• Business Districts: 20 mph

• Residential & School Districts: 25 mph

• Residential Areas near City Borders: 45 mph

• Highways: 55 mph

We may increase these limits if the road is designed to handle higher speeds safely.

3. Other factors we consider

Before changing a speed limit, we also look at:

• The condition of the road surface.

• How many people are walking or parking nearby.

• The history of accidents in that specific area.

4. Where do we put speed limit signs?

We place signs at the beginning of a road and at specific spots where drivers need a reminder. Our goal is to make sure you always know the safe speed for the stretch of road you are on.

We don’t just put signs wherever there’s an empty spot. We follow specific safety rules to make sure they are helpful and easy to see. Here is how we decide:

1. The Type of Sign

Different signs have different "jobs," which determines their location:

• Action Signs: Signs like "Stop" or "Speed Limit" are placed exactly where the driver needs to take action.

• Warning Signs: Signs for things like "Narrow Road" or "Railroad Crossing" are placed well ahead of the hazard so you have plenty of time to react.

• Direction Signs: We place mile markers and service signs at logical points to help you find your way.

2. Consistency (Staying on the Right)

Most signs are placed on the right side of the road. Why? Because that’s where drivers naturally look. We only put signs overhead or in "unusual" spots if there isn't enough room on the side or if the road is extra wide.

3. Spacing and Timing

We space signs out based on how fast cars are traveling. If we pack too many signs too close together, it’s hard for drivers to read and process everything. We want to give you enough time to read the sign and make a safe decision without feeling overwhelmed.

4. Public Property

By law, we only place city street signs within the public right-of-way (the land owned by the city next to the road). We also make sure they are placed in clear view where you expect to see them.

It may be surprising, but adding more stop signs or traffic signals does not always slow drivers down or make a road safer. When these tools are used where they aren't truly needed, they can actually cause new problems.

1. Too many signs lead to "sign blindness"

When stop signs are placed at intersections where they don't seem necessary, drivers can become frustrated or careless. Over time, they may start performing "rolling stops" or ignore the signs entirely, which creates a major safety risk for everyone.

2. Unnecessary signals cause traffic jams

Installing traffic lights where they aren't needed can create unnecessary congestion and add to your travel time. Frustrated drivers are more likely to drive impatiently or take risks to "make up" for the time they spent sitting at a red light.

3. Simpler options are often safer

To keep traffic moving safely, we only install stop signs and signals where they are absolutely necessary. Often, a simpler solution—like a Yield sign—provides enough safety without causing traffic to back up or encouraging impatient driving.

It can be frustrating to see road stripes wear out quickly. While it seems like there should be one "best" way to paint lines, we actually choose materials based on the specific road, the budget, and the weather.

1. Cost and Durability

We use two main types of materials for road stripes:

• Standard Paint: This is the most common and least expensive option. It usually lasts between six months and two years.

• Durable Materials (like Epoxy): These materials last much longer but are significantly more expensive. We typically save these for newer roads or high-traffic areas where we want the lines to stay visible for several years.

2. Road Condition

The type of road surface matters. For example, older roads or roads that will be repaved soon usually get standard paint to save money. On newer asphalt or concrete, we use thicker or more durable materials that can "grip" the surface better.

3. Weather and Snow Plows

Iowa's weather is a major factor. Stripes applied in the warm summer months stick better and last longer than those applied in the cold. Additionally, snow plows can scrape more expensive, raised markings right off the road, so we often stick to flatter materials that the plows can glide over.

4. Traffic Volume

The more cars and heavy trucks that drive over a line, the faster it disappears. High-traffic intersections and turning lanes will almost always wear out faster than quiet residential streets.

Adding four-way stop signs might seem like a quick way to slow down drivers, but they don't always make a street safer. If stop signs are used where they aren't truly needed, drivers may start to ignore them.

Our traffic engineers look at several factors before deciding to install a four-way stop:

1. The risks of using too many signs

Studies show that when there are too many stop signs, drivers can become frustrated or impatient. This leads to:

• "Rolling" stops: Drivers may stop only halfway or fail to stop at all.

• Reckless driving: Drivers may speed up between signs to make up for lost time.

2. When we use four-way stops

We typically install four-way stops at intersections where the two crossing streets have about the same amount of traffic. We also consider them if:

• A signal is coming soon: We need a temporary way to control traffic before a permanent traffic light is installed.

• There is a history of crashes: At least five preventable crashes have happened at that spot within a year.

• High speeds: The road has very high speeds or a large volume of cars that makes turning dangerous.

3. Other ways to improve safety

Often, there are better ways to make an intersection safe without adding a four-way stop. We may try these first:

• Improving visibility: Moving the painted "stop line" so drivers can see further down the road.

• Adding lights: Installing flashing yellow or red lights to make the existing signs easier to see.

• Street lighting: Adding street lights to help drivers see better at night.

• Managing driveways: Limiting driveways near the intersection so drivers don't have to deal with unexpected cars pulling out.

While having more driveways might seem like it would make a business easier to reach, adding extra entrances actually creates safety risks and can make traffic more difficult for everyone.

1. More driveways can lead to more crashes

Every time a car turns into or out of a driveway, the rest of the traffic has to slow down or stop. When a street has too many driveways, traffic becomes "stop-and-go." Studies show that this constant stopping leads to more accidents. By using fewer driveways or sharing one with a neighbor, traffic flows more smoothly and safely.

2. Location is just as important as number

Driveways need to be placed in the right spots to stay safe. They should be a healthy distance away from intersections so they don't interfere with traffic lights. They also need to be in a spot where drivers can see clearly in both directions before pulling out.

3. Fewer driveways are better for business

You might worry that fewer driveways will hurt your sales, but recent studies show the opposite. Drivers often avoid streets where they have to constantly slam on their brakes for cars turning into driveways. Businesses on streets with well-designed, limited entrances often have the same or even better sales than those with many driveways.

It’s a common misconception that adding a flashing light to a sign automatically makes the road safer. While it seems like a great way to get drivers to notice a sign and slow down, traffic engineers have found that it doesn't always work that way.

Here is the breakdown of why we use flashing lights sparingly:

1. They are for "Surprises"

Flashing lights work best when they warn drivers about something they wouldn't expect—like a hidden narrow bridge, a sudden sharp curve, or an obstruction in the road. If the road is normal and easy to see, a flashing light usually isn't necessary and won't make the area any safer.

2. Overuse Leads to "Sign Blindness"

If we put flashing lights on every sign, drivers start to tune them out. Eventually, people stop paying attention to them altogether. Even worse, drivers might start ignoring regular signs that don't have lights, thinking they aren't as important.

3. Standard Signs Usually Work

In most cases, a standard, well-placed sign is more than enough to give drivers the information they need. We save the flashing lights for high-speed rural roads or busy areas where pedestrians cross frequently to make sure the lights keep their "warning power."

It might seem like a power-up for safety, but adding a traffic signal doesn't always prevent accidents. In fact, if a signal is put in where it isn't really needed, it can actually make things worse. Drivers often get frustrated by the extra wait, which leads to risky moves like speeding to beat a yellow light or ignoring the signal entirely.

How we decide

We don't just guess; we follow national safety standards to make sure a signal will actually help. We typically only install one if there is:

• Heavy Traffic: A very high volume of cars or people walking.

• Crash History: A documented pattern of severe accidents that a signal could solve.

• School Safety: A specific need for children to cross a busy road safely.

Better ways to stay safe

A traffic light can’t stop things like distracted driving or speeding. Before we commit to a signal, we look at other tools that often work better and faster:

• Turn Lanes: Giving drivers a dedicated space to wait so they don't block traffic.

• Better Lights: Improving street lighting so everyone is more visible at night.

• Clearer Signs: Using bigger or more reflective warning signs.

• Crosswalks: Adding bright, marked paths for pedestrians.

Many people believe that lower speed limits automatically make roads safer. However, traffic studies show that lowering a speed limit does not always reduce crashes. Here is why:

1. Slower is not always safer

While high-speed crashes can be more serious, higher speed limits do not necessarily cause more accidents. For example, interstates have the highest speed limits but also have the lowest crash rates. This is because those roads are designed for consistent speeds.

2. Safety comes from everyone driving the same speed

The safest road is one where every car is moving at about the same speed. When a speed limit is set too low, some drivers ignore it while others try to follow it. This creates a dangerous mix of fast and slow traffic on the same road, which is a major cause of accidents. It is actually safer for everyone to be moving at the same speed—even if that speed is higher—than to have cars traveling at very different speeds.

3. How we choose the limit

We usually set speed limits based on the speed most people already drive comfortably. We also look at:

• The condition of the road surface.

• How many people are walking or parking nearby.

• The history of accidents in that area.

Our goal is to find a balance that keeps traffic moving at a steady, predictable pace for everyone’s safety.