UPDATED: Nighttime and weekend closures scheduled next week as part of I-84/Karcher Interchange reconstruction

Aug. 23 update: Weekend closures scheduled for Aug. 24-Aug. 27 have been postponed. New dates will be shared in the new future.


BOISE– Ongoing improvements to the Interstate 84/Karcher Interchange in Nampa will require two closures the week of August 20. Motorists should plan ahead and consider an alternate route on the following dates:

Wed., Aug. 22 at 8 p.m. to Thurs., Aug. 23 at 5 a.m.: The interchange will be closed while crews install new traffic signals at the Midland Boulevard/Karcher Bypass intersection and remove two overhead signs. Midland Boulevard, Karcher Bypass, Exit 33 A, 33B and the westbound entrance ramp will all be closed to traffic. Motorists will be detoured via Nampa/Caldwell Boulevard and the Karcher Connector.

Fri., Aug. 24 at 8 p.m. – Mon. Aug. 27 at 5 a.m.: Exit Ramp 33A will be closed to traffic while crews reconstruct and modify the ramp. Westbound I-84 motorists will be directed to use Exit 35 at Northside Blvd instead of Exit 33A during this closure.

The project includes the following improvements:
*Eliminating exit 33B and adding lanes at exit 33A/Midland Blvd.
*Adding a second southbound lane to Midland Blvd.
*Adding a second left turn lane from the Karcher Bypass to southbound Midland Blvd.
*Upgrading sidewalks and traffic signals

To sign up for construction updates, please email Jennifer.gonzalez@itd.idaho.gov or call 208.334.8938.

The Sunday Backup: Idaho Highway 55 and the Banks-Lowman Intersection

Intersection of ID-55 and Banks-Lowman Road

Every summer, thousands of residents from the Treasure Valley escape the heat of the valley floor and head north into the cool beauty of the mountains, especially on weekends. When it’s time for all those people to head home Sunday night, traffic can get congested on our mountain roads.

Recently, a number of people have reached out to ITD concerned about one intersection in particular: Idaho Highway 55 and the Banks-Lowman Road. Those who sought recreation and cooler climes in Crouch or Garden Valley can find themselves in a long line of vehicles waiting to turn left (south) onto ID-55.

So, what’s to be done? Why is congestion so bad? What’s ITD doing about it? This article is part of an effort by the Idaho Transportation Department to provide information about the situation, what the Department is doing, and what some options may be moving forward.

The Situation

Graph of Daily Weekday Traffic on 2-lane facilities

Idaho 55 is a major corridor connecting the Treasure Valley, and some of the most pristine recreational destinations in America: Garden Valley, Cascade, Donnelly, and McCall. also one of two options for Treasure Valley residents to access Central and Northern Idaho, the other being US-95.

Because of this, ID-55 sees a major increase in traffic on the weekends. On a typical summer weekday, the section by Banks sees about 6,500 trips, split equally headed north and south. So there’s roughly 3,250 cars heading north and 3,250 cars heading south in a given day.

To give you a point of reference, let’s compare that section of ID-55 with other two-lane facilities in Southwest Idaho. ID-55 in Nampa sees around 18,500 weekday trips. US-20/26 in Meridian sees around 21,000 trips each day during the week. And a two lane section of ID-44 (State St.) west of Eagle experiences 23,500 daily trips in the work week.

The traffic situation does change on summer weekends for the section of ID-55 by Banks. Traffic significantly increases and is directional. On Friday and Saturday, most of that traffic is heading north. On Sunday, nearly all that traffic is heading south.

Graph of Daily Traffic S of Banks-Lowman/ID-55 intersection

You can check out our traffic counts by visiting our website.

The high volume of southbound traffic does mean it can take a while for a safe opening to appear for those waiting to turn left out of the Banks-Lowman Road. Between the waits for an opening, and the increased number of people leaving the Garden Valley area, you get congestion and increased drive times.

What does this mean? When we look at the data, the intersection of ID-55 and the Banks-Lowman Road functions well Monday through Saturday. On Sunday, for a few hours in the afternoon as everyone that traveled up during the week heads home, traffic on ID-55 is heavy and speeds are reduced. The flow on ID-55 is reasonably uninterrupted but there are long wait times for those turning left on the highway from the Banks-Lowman Road. Data reveal the significant congestion concern primarily happens for a few hours during the 15 Sundays of summer (Memorial Day to Labor Day).

Safety of the intersection

In addition to the concerns of congestion, people are concerned this might be a dangerous intersection. We can look to the data and see how things compare.

Our current confirmed traffic crash data goes up to 2016. If we look at the five-year history of this intersection, from 2012-2016, there have been 4 reportable crashes. Two of those crashes resulted only in property damage. One resulted in one person suffering minor injuries. The final crash resulted in one serious injury and two minor injuries. We are aware of the crash that occurred recently, involving the tragic loss of one life and injury to several others, not yet reported in our database.

Additionally, the Department tracks High Accident Locations (HAL) across the state and ranks them. The ranking is determined by the frequency of crashes (how many there have been), the severity of those crashes, and the rate of crashes (crashes per 1 million miles traveled). Based on current data, this intersection does not rank in the top 1,000 HAL intersections across the state. By comparison, the intersection of ID-55 and ID-44 in Eagle is #92.

ITD’s Action

As the Department weighs decisions, a number of factors are taken into consideration. Data, such as that outlined above, is one of those. The Department’s mission is “Your Safety. Your Mobility. Your Economic Opportunity.” So we gather the best data regarding these three factors to make sound decisions on how to best invest our limited transportation dollars

We care about you, the people of Idaho who we serve. Hearing from you is very important to us. It’s important we give you the information so you see what we see, and better understand how we make these decisions.

Our main effort to mitigate heavy weekend travel at this intersection is to flag it during the holiday weekends, when traffic is at its highest. Those weekends are Memorial Day, Fourth of July, and Labor Day. Flagging is effective because the person at the intersection can make judgement calls in the moment and quickly stop and redirect traffic. Flagging costs the Department around $5,000 a day.

A long-range solution

Flagging can help improve traffic flow on busy weekends, but Idaho is growing and traffic is growing with it. So what can be done to decrease congestion at the ID-55 and Banks-Lowman Road intersection?

Before exploring these, it’s important to once again put this intersection in context. It does not rank high in terms of congestion or safety concerns. That’s a significant consideration when it comes to getting the most bang for the taxpayers’ buck. That said, ITD has been investigating possible opportunities for changes.

The following are some of the solutions ITD is exploring. Currently, there are no plans to implement any of these. Each of them will have trade-offs we want the public to consider.

1. Traffic Signal

This is the most popular suggestion we’ve received from the public. It’s an understandable solution. If the problem is cars coming down ID-55 not giving an opening for those turning out of Banks-Lowman, put in a signal to stop the highway traffic long enough to move some people out.

Traffic SignalWell, it gets a little more complicated than that.

First, the one-lane bridge to the boat landing, owned by the United States Forest Service, makes for an unusual intersection. In order to safely direct traffic on and off that leg, you need some extended signal timing, which will add considerable wait times and therefore congestion, primarily to ID-55, but also impacting Banks-Lowman Rd.

Another concern is that a signal will force the currently free-flowing traffic on ID-55 to stop. This creates a queue. As that queue backs up, major safety concerns arise. Imagine a driver coming down the mountain going 55mph, turning a corner and suddenly coming upon break lights. A signal adds new safety and mobility concerns, with every bit as much risk of serious injury as the existing condition, and possibly more overall delay for travelers.

2. Roundabout

A roundabout can keep traffic flowing and provide better opportunity for those coming off Banks-Lowman to get onto the highway.

Aerial view of the ID-55/Banks-Lowman intersection
Aerial view of the ID-55/Banks-Lowman intersection

Again, you have the issue of the one-lane bridge complicating things. Legs of a roundabout typically allow two-way travel.

Roundabouts also require a big footprint, something this intersection doesn’t have. Things are very tight with three of the quadrants bordered by rivers and the last hugging a mountainside. A roundabout would either require a massive bridge structure or significant carving out of the mountainside.

3. Third Lane

The Department has begun exploring the option of adding a third lane that would accept southbound traffic. The concept is this lane be open for left-turning traffic from Banks-Lowman to turn into that serves as a refuge from ID-55 southbound traffic. A vehicle could turn into this lane and gain speed to merge with ID-55.

We anticipate this project would require a new bridge on the south leg of the intersection to accommodate the extra lane, and we’d have to cut into the mountainside north and south of Banks-Lowman to make room for the lane and the tapers before and after.

The silver lining for this option is the age of the bridge on ID-55. Though it is safe today, it will have to be replaced in the near future due to its age and condition. Replacing it with a wider bridge becomes much more cost-effective at that time. Currently, this bridge is not scheduled for replacement in our 7-year plans.

The Bottom Line

We have absolutely heard from those of you wanting ITD to “fix this problem.” Hopefully this article shows we continue to look at ways to address the issue and that there’s no easy solution.

As we consider all of these actions, we have to weigh the cost benefit. The long-range options explored above will cost tens of millions of dollars. And in the context of crash data and congestion, it is far from our highest priority. That does not eliminate the possibility of making improvements, it just makes it much harder.

In the meantime, we continue to commit to flagging on the busy holiday weekends. We will continue to explore other alternatives.

We also encourage those who recreate on the weekends along this corridor to plan ahead. Consider leaving earlier or later to avoid the heaviest travel times. Consider alternate routes such as Idaho Highway 21 – the folks at Lowman and Idaho City would be happy to see you. Most importantly, anticipate that congestion is a reality during the summer weekends and use your best behavior to stay safe and keep your fellow motorists safe.

New traffic signals, roadway improvements to improve safety on Idaho Highway 69 in Meridian

The Idaho Transportation Department will begin constructing a series of safety improvements on Idaho Highway 69 (Meridian Road) in Meridian and Kuna next week. Motorists are advised to expect nighttime lane restrictions on the highway until early October.

Improvements will include:

  • Resurfacing ID-69 between Orchard Avenue in Kuna and Overland Road in Meridian.
  • Adding traffic signals at Hubbard and Lake Hazel roads.
  • Installing a median barrier to reduce left-turn crashes between Calderwood Drive and Overland Road.
  • Reconfiguring lanes at the intersection of Meridian and Overland roads to improve traffic flow.

ITD worked closely with the city of Meridian and Ada County Highway Department to develop the improvements after a recent safety analysis of the corridor. Crashes on ID-69 increased by nearly 50 percent between 2011 and 2016. ITD reached out to businesses earlier this year to discuss plans for this project.

Throughout this project, crews will work from 8 p.m. to 6 a.m. on week nights (Sunday-Thursday) and 9 p.m. to 6 a.m. Friday and Saturday nights. One lane will be closed in both directions and flaggers will direct traffic at intersections. All lanes will be open during the day.

To request email updates about this project, text SH69 to 22828. For more details, visit itdprojects.org or contact ITD at (208) 334-8938 or Jennifer.gonzalez@itd.idaho.gov.

Construction will begin on Idaho 55 next week (July 16) near McCall

Idaho 55 Zachary to Goose Creek Map

The Idaho Transportation Department will begin a project next week (July 16) to resurface Idaho Highway 55 between New Meadows and McCall and construct a new retaining wall east of Brundage. The project will improve driving conditions and safety on this heavily traveled route.

From July to late August, crews will work between Zachary Road in McCall and Goose Lake Road near Brundage. View the postcard for details.

In order to keep traffic moving during the busy summer season, crews will work from 12 a.m. Monday to 12 p.m. Friday. All lanes will be open on weekends.

During the week, ID-55 will be reduced to one lane both day and night with a pilot car directing traffic. The speed limit will be reduced and 12-foot width restrictions will be in place.

“This will be a tight construction zone and we are asking for drivers’ patience during the work week. Please slow down in the work zone and pay close attention to signage, as crews will be working close to traffic,” said ITD Project Manager Jim Hoffecker.

Construction will move to the area between Goose Lake Road and Goose Creek Grade in late August. The project is expected to be completed this fall.

Nampa to Marsing, ID-55 preservation projects begin after 4th of July Holiday week

Map of seal coat project on ID-55 from Nampa to Marsing

A pavement rehabilitation project between Nampa and Marsing is scheduled to begin July 9 and conclude in late July/early August. Work will seal the pavement and extend the life of the roadway.

The first phase, a six-mile micro-seal from Nampa-Caldwell Boulevard to Farmway Road, will occur in the evening (10 pm – 5 am). Work is expected to conclude the week of July 16.

The second phase, an eight-mile chip-seal from Farmway to the Snake River Bridge at Marsing, will occur during daylight hours. Work is expected to conclude in late July.

During both phases, motorists can expect reduced speeds and up to 15-minute delays as traffic will be periodically reduced to one-lane with a pilot car guiding traffic. Where work is occurring, intersections will be controlled by flaggers with minimal delays. Motorists are encouraged to drive with caution through the work zone.

Schedules are subject to change. The contractor is permitted to work weekends. For up-to-date construction information, visit 511.idaho.gov.

Single lane closure on eastbound I-84 Sunday July 1

Cloverdale Lane Closure

The Idaho Transportation Department will close the left-most lane of eastbound Interstate 84 beneath the Cloverdale Overpass Sunday, July 1. This will allow crews to perform work in preparation for replacing the damaged bridge.

Crews will drill beneath the existing bridge to test the soil composition. This will inform what treatment is needed for the foundation of the replacement bridge for Cloverdale Road. The replacement, currently being designed by ITD engineers will feature four 11-foot travel lanes, 5.5-foot raised bike lanes, and 7.5-foot sidewalks.

The single-lane closure is expected to begin early Sunday morning and stay in place for most of the day.

Drivers are encouraged to use caution in the work zone. For updated information on traffic impacts on the State Highway System, please visit 511 online at 511.idaho.gov.

ITD begins work to replace Cloverdale bridge over I-84 with support of ACHD Commissioners

The Ada County Highway District Board of Commissioners voted unanimously to support ITD’s plan to replace the Cloverdale Road bridge over Interstate 84.

The concurrence provides a unified front for ACHD and ITD on how best to address this emergency. The Idaho Transportation Board passed a resolution last week to replace the Cloverdale bridge with a $6-8 million structure.

ITD and ACHD developed a preliminary design for the replacement bridge that will match the county highway district’s long-range plans for Cloverdale Road. ITD District 3 Engineer Amy Revis presented this plan to the ACHD Board on Wednesday. It includes four 11-foot travel lanes, a 5.5-foot raised bike lane, and a 7.5-foot sidewalk.

“I am grateful for the full support of the ACHD Board of Commissioners,” said Revis. “The collaboration between our agencies will help create a bridge that will serve this area well for many years to come. I ask the public to exercise patience as we construct these needed improvements.”

ITD engineers have already been gathering information needed for designing the replacement bridge. When a design is complete, the department will seek bids from contractors to construct the bridge.

The old bridge will remain closed until the new bridge is complete, which is expected to take 12 months. ITD closed the Cloverdale bridge due to extensive damage caused by a fatal crash Saturday, June 16.

The replacement will not include on- or off-ramps to I-84. ITD’s goal is to reopen the important crossing point at Cloverdale quickly. The study and analysis of adding ramps and alternative actions in the area would greatly delay that goal.

ITD releases traffic control plan used for Interstate 84 construction

The Idaho Transportation Department has received interest regarding the traffic control plan for the Five Mile to Orchard project on Interstate 84. You can see the entire traffic control plan for project by clicking here.

ITD Construction projects that have shoulder or lane restrictions are required to include a traffic control plan that meet the standards included in the federal and state approved Manual on Uniform Traffic Control Devices (MUTCD). These contractor traffic control plans are used to set up signs, barrels, and other traffic control devices for a project.

Below is a brief description of the traffic control plan:

First, the plans for advance warning signs before the lane reduction. This information can be found on page 14 of the traffic control plan.

A section of the traffic control plan for warning signs before the lane closure and construction
A section of the traffic control plan for warning signs before the lane closure and construction

The first sign a motorist would encounter is a portable changeable message sign on the right shoulder. This sign read “NIGHT WORK THRU JUNE: CHECK 511”. This sign was placed on the east side of the Eagle Road Overpass.

A minimum of 1,500 feet after the portable changeable message sign, the plan calls for a 4’x4’ orange diamond signs on both shoulders that read “ROAD WORK AHEAD.”

A minimum of 1,000 feet after the “ROAD WORK AHEAD SIGN” the plan calls for a 6’x3’ white rectangular signs on both shoulders that read “INCREASED FINES FOR WORK ZONE SPEED VIOLATIONS.” Following these signs, a minimum of 1000’ away 4’x4’ orange diamond signs on each shoulder are placed with a “SPEED LIMIT 55” box and arrow pointing up indicating a speed limit reduction ahead.

A minimum of 1,000’ feet beyond these orange diamond sign, the plan calls for 4’x5’ white and black rectangular signs on both shoulders reading “SPEED LIMIT 55.” At this point, drivers have seen four signs on each shoulder over a minimum of 4,500 feet. All of this signage is placed before the lane restriction begins.

The next section ITD highlights is the beginning of the construction zone. This information can be found on page 12 of the traffic control plan.

A section of the traffic control plan showing the placement for signs and barrels before, through, and after the construction zone
A section of the traffic control plan showing the placement for signs and barrels before, through, and after the construction zone

A minimum of 1,000 feet after the “SPEED LIMIT 55” signs discussed above, the plan calls for 4’x4’ orange diamond signs on both shoulders indicating the number of lanes closed ahead. This project closed the three left lanes and the signs at this location on the field read “3 LANES CLOSED AHEAD.”

A minimum of 1,500 feet after these signs, the plan calls for 4’x4’ orange diamond signs on both shoulders indicating the left lane is closing ahead (sign 8 in the figure above). A minimum of 1,000’ after this sign, the taper to close off the lane begins.

The plan allows for two options on how to execute a taper. One option is to have a continuous taper closing all three lanes over 1,980 feet. The second is to have three separate tapers, with a tangent (straight) section between each taper.

The plan for this option is detailed as follows. At the beginning of each taper, an illuminated merge right arrow sign is placed. Orange drums with retroreflective lines are used for each taper and tangent section, spaced no more than 55 feet apart.

Each taper must extend a minimum of 660 feet. At the end of each taper, a minimum straight segment (identified as tangent on the plan sheets) of 1,320 feet (1/4 mile) extends until the beginning of the next taper.

Overall, from the first notice of construction at the portable changeable message sign to the final single lane of travel, a vehicle traveling the maximum legal speed would have more than two minutes and twenty seconds to make the appropriate maneuvers and be in the proper lane.

Operational improvements at I-84/Karcher Interchange in Nampa to begin in July

BOISE -The Idaho Transportation Department and the city of Nampa will begin operational improvements and modifications to the ramps at the Interstate 84/Karcher Interchange in Nampa beginning the week of July 9. The project is scheduled to be complete this fall.

Construction will include:

*Eliminating exit 33B and adding lanes at exit 33A/Midland Blvd
*Adding a second southbound lane to Midland Blvd
*Adding a second left turn lane from the Karcher Bypass to southbound Midland Blvd
*Upgrading sidewalks and traffic signals

Motorists should plan ahead and be prepared for shifts in traffic patterns, periodic ramp closures, and other detours during construction. A map of the work zone is available here.

To sign up for construction updates, please email Jennifer.gonzalez@itd.idaho.gov or call 208.334.8938.

The project is being funded jointly by the city of Nampa and ITD. Central Paving is the contractor.

Cloverdale Road Overpass to remain closed for safety of the traveling public

Cloverdale Rd Overpass is closed for repairs following a fiery crash

The Cloverdale Overpass Bridge will remain closed indefinitely following a fiery crash on Interstate 84 late Saturday evening.

The fire significantly damaged a section of the overpass. ITD inspectors have evaluated the damage and determined the bridge is not safe to travel on. The bridge will remain closed until full repairs can be made. ITD has assessed it is safe for traffic travelling underneath the bridge on I-84.

ITD will develop an emergency contract to make repairs as quickly as possible. At this time, the department plans to remove and replace the damaged section. This is expected to take several months to complete. Details on the schedule, cost, and traffic impact of repairs will be shared as they are developed.