Adding lanes won’t address all the congestion problems on I-70. What happens to traffic once it exits the interstate can have a profound impact on safety and efficiency along the “main line.”

We’ve all seen it happen – stop lights and turning movements near the end of an exit ramp cause traffic to back up – sometimes ramp traffic can back up out to the main lanes of I-70. On the cross road, backups can create gridlock conditions in the interchange area that makes access to businesses difficult. This creates extremely hazardous conditions for all travelers. In fact, up to 68 percent of all crashes are access related.

Widening and reconstructing I-70 will require that every interchange be rebuilt. This provides the opportunity to incorporate the latest methods for improving interchange safety and efficiency.

One such method is the use of access management measures to control the number and location of access points near an interchange. Another is the use of innovative design solutions, such as the Single Point Urban Interchange (SPUI). While most interchanges along I-70 will likely be rebuilt in a configuration much like what is there today, conditions in some locations may require the interchange to take a new form. The SPUI is now being used with greater frequency in Missouri, and could be considered in the more urban areas along I-70. The use of roundabouts at nearby intersections is another method for improving traffic flow and safety in the area of an interchange.

More detail about access management, SPUIs and roundabouts can be found by clicking on the links above.

Access Management

Access management is a process that involves thoughtful planning and design to determine the location and number of interchanges, driveways and other access points. Implementation of a successful access management plan can:

• Reduce crashes by as much as 50 percent
• Increase capacity by 23-45 percent
• Reduce travel time and delay by 40-60 percent
• Decrease fuel consumption by 35 percent
• Extend the life of the highway
• Reduce vehicular emissions
• Reduce transportation costs
• Promote consistent treatment of applicants for access permits
• Protect investment in abutting property

There are many benefits to applying access management principles in the reconstruction of I-70, but there will certainly be costs, as well. In order to create a safe environment for all travelers, the basic design of some interchanges and access to facilities just off the interstate will likely change. What’s important to understand is that access management does NOT mean access elimination.

How will Access Management issues be addressed?



Through the second tier studies, MoDOT and its consultants will work closely with area business owners and residents to determine the best way to address access issues. This cooperative effort will strike a balance between keeping travel on I-70 and through the interchange safe and efficient, and providing access to facilities near the interstate.

MoDOT and FHWA policies will guide decisions about access management. These policies establish criteria for interchange spacing and the location of driveways and outer roads near exit ramps. As it concerns I-70:

Application of access management measures will maintain smooth traffic flow as vehicles enter and exit the highway – and provide a safer driving environment once off the highway.

Single Point Urban Interchange

Interchanges in heavily developed urban areas must move an ever-increasing volume of traffic through limited amounts of space. One way to maximize the flow of traffic in urban areas is through use of Single Point Urban Interchanges.

The Single Point, also known as an X-interchange or an Urban Diamond, is being used extensively in urban highway construction and reconstruction across the country. The simple design makes the most of safety, capacity and efficiency.

The name “Single Point” refers to the fact that all thru-traffic on the arterial street – and all the traffic turning left onto or off of the interchange – can be controlled from a single set of traffic signals. These interchanges allow long, gradual turns (helpful to larger vehicles like trucks and buses), and have the ability to move more traffic through a smaller amount of space. Smaller space means that single points can typically be built within existing state property.

Not all interchanges along the I-70 corridor will be appropriate for single points. Their use will be considered primarily in heavily-developed areas such as Columbia and St. Louis.

Roundabout

While not an interchange design, roundabouts can be used at intersections located near an interchange to help increase safety and keep traffic moving.

A roundabout is a way to get large volumes of traffic through an intersection quicker, safer and more economically. Used in many foreign countries, the one-way circular intersection channels traffic around a central island without the use of traffic signals. Drivers slow down as they approach the roundabout and yield to the traffic already circulating. Drivers then enter to the right when a gap opens, keeping the free-flowing movement going. By yielding instead of stopping at a signal, motorists can be on their way quicker.

Roundabouts add to driving safety by reducing a signalized intersection’s 22 conflict points (spots where vehicles could collide) to eight. The fewer conflict points, combined with slower speeds and calmer traffic, can translate into fewer – and less severe – crashes. Roundabouts help lower costs by reducing driver delay, which saves time and fuel, and reduces pollution. The state also benefits by eliminating about $5,000 per year in maintenance of signals and electricity costs.