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Iowa in Motion 2045 - Data analysis is in line with public comments on long-range planning

01/20/2017

IA-Motion_horizontal_color-gradient.fwAs 2017 kicks off, the Iowa Transportation Commission and Iowa Department of Transportation staff are moving into the final phase of the draft long-range transportation plan: Iowa in Motion 2045. Overall, there have been very few surprises in the data analysis and public input segments related to the planning effort.

“That’s a good thing,” said Garrett Pedersen, with the Iowa DOT’s Office of Systems Planning. “The public’s expectations and the data collected on the needs of our transportation system are matching up with the ideas the Iowa Transportation Commission and Iowa DOT staff are formulating into a plan.”

Highway-needs-analysis_urban-op-bridgeThe final pieces in the highway system analysis included looking at the capacity of state-managed roadways in urban areas, the condition of the bridges on the state system, and an overview of how efficiently roadways are functioning.

As you may have read in our November blog post, part of the planning effort included a look at highway capacity statewide. Andrea White, with the Iowa DOT’s Office of Systems Planning, said, “For the next step in the planning process, we looked specifically at which urban roadways are most in need of added capacity.”

To accomplish this, Iowa DOT staff worked with the metropolitan planning organizations (MPOs) in Iowa’s nine largest urban areas. White said, “The MPOs have travel demand models similar to what we used to look at statewide capacity, but have more detailed data for their urban areas. This helps better pinpoint urban locations where projects could be implemented to improve traffic flow.”

White added, “The data analysis aligned with what public input had already indicated as to the areas where improvements would be beneficial. Specifically, the statewide analysis identified I-80 from Dallas County to the Mississippi River, I-380 from Iowa City to Cedar Rapids, and I-35 from Des Moines to Ames. The urban analysis identified a total of 34 corridors across the nine metro areas.”

Statewide Capacity - Metro 2

The next step in the highway analysis was reviewing where operational solutions could be used to help traffic move more smoothly. In many cases, that may not mean building more lanes, but instead, using strategies outlined in Iowa DOT’s Transportation Systems Management and Operations (TSMO) efforts. Solutions suggested by the TSMO plan include updated signal timing, implementing urban interstate ramp metering, improved traveler information using 511 and dynamic message signs, and increasing assistance of services like the Highway Helper Program, among other strategies.

To help prioritize where these types of strategies would be the most beneficial, an analysis of the interstate system looked at several operational-related factors, including crash rate, traffic bottlenecks, weather sensitivity, and amount of traffic. Pedersen noted, “The analysis of operations issues on interstates was possible due to readily available data from sources like INRIX. This data is often not as complete for other highways, which is why we focused the analysis on the interstate system. Also, interstates are the TSMO plan’s top priority for where to implement operations improvements.”

ICE OPS version3

The final piece of analysis for the state’s highway system addressed the needs of Iowa’s bridges. Since the I-35W bridge collapse in Minneapolis in 2007, the media has been focused on two rating criteria related to bridges: functionally obsolete and structurally deficient. While the rating system used to determine these qualifiers is sound, the terms are a bit confusing in that neither rating necessarily indicates the level of repair needed. The Iowa DOT’s approach to addressing bridge needs utilizes a bridge condition index, similar to the type of data collected and analyzed for the condition of the highway system you read about in our December blog post. The analysis focused on identifying the bottom 5 percent of bridges in the state by condition as a tool to assess needs. The actual prioritization of bridge needs involves many other factors in order to maximize benefits and reduce life-cycle costs.

Bridge Database - version3

As you can see, delving into the data reveals a number of issues that won’t be quickly or easily resolved. It’s the Iowa DOT’s mission: “To get you there safely, efficiently and conveniently.” We will continue to use both public input and data to drive decisions that accomplish that mission.

This concludes the series of blog posts on planning for the future of Iowa’s highway system. Look for upcoming posts about planning efforts for other modes – aviation, bicycle/pedestrian, public transit, rail transportation, and waterway – and how the Iowa in Motion 2045 planning effort will wrap up this spring.


Previous Iowa in Motion 2045 blog entries
Nov. 1, 2016: Iowa’s Long-Range Transportation Plan continues to sharpen the focus on future needs

Dec. 22, 2016: Iowa in Motion 2045 – connecting the dots to improve the transportation system


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Iowa highway in the evening