Friday, February 20, 2009

Modern Parkway: Carmel, Indiana

This post showcases a modern approach to the precursor of the modern freeway: the grade-separated parkway. In Carmel, IN, Keystone Ave. (formerly IN-431) runs just east of the Civic Center, between US-31 to the north, and I-465 to the south. A 4-lane facility, with at-grade intersections with the primary cross-streets, Keystone Avenue needs congestion relief, and dissatisfied with INDOT's solution of adding another lane to each directional flow, Mayor Jim Brainard decided to revive the old form of the urban parkway, a grade-separated road with emphases on context-sensitivity, nature, and safety. Unlike the Arroyo Seco Parkway, or the original parkways back East, Carmel is implementing roundabout interchanges so as to minimize the footprint of the grade-separations. The following link takes you to the project website, where you can find pictures, videos, renderings, and other information about this endeavor that is unique in the United States, but borrows from concepts present in Europe:

Project CarmelLink

My Thoughts

The Good:
  • Attention to detail, particularly with regards to aesthetics.
  • Grade-separation at key intersections.
  • Parkway depression instead of elevation transforms a series of auto-oriented, pedestrian-unfriendly intersections into potential linkages connecting eastern Carmel to the central core.
  • Use of compact, dual "teardrop" roundabouts instead of traditional diamond interchanges or expensive SPUIs.
  • Because of limited depression, on- and off-ramps are shorter, so closeness of interchanges should not be an issue (~ between 1.1 and .4 miles apart)
  • Bicycle-friendly
  • Planned hardscape improvements
The Bad:

  • Currently planned 40mph speed limit is a 10mph reduction over current configuration, and bears no correlation to design speeds; blatant revenue-generator.
  • Raised curb median is not appropriate for the intuited driving speeds.
  • Horizontal cross-section may be insufficient to widen in the future with adequate shoulder space.
The Unknown:

  • Would raised planters with landscaping surrounded by Jersey barriers (Caltrans: K-rails) improve crashworthiness?
  • Will adequate advanced signage of turning movements at roundabout interchanges be installed?
  • What about 131st St./Main St.? How will this interchange interact with the interchanges at 126th and 136th Streets? Will proximity be an issue?
  • Will "weave lanes" be striped between interchanges?
  • What about metering?

Despite these questions and criticisms, I rate this project very highly. The vision is far greater than anything any other cities in Indiana attempt to create, and the potential for this to be regarded as Mayor Brainard's legacy is high; Carmel just won the bid to host the 2011 National Roundabout Conference and has more roundabouts inside the city limits than anywhere else in the United States (40+ built, ~80 in total planned), and all were implemented by Mayor Brainard.

What are your thoughts?


Alan Huynh said... glad to have you back on the blog. Your comments and posts are always insightful.

I have looked on the website provided, but have been unable to find much information detailing the problems of the present infrastructure setup or the context for the need to make such improvements.

I'm sure that because you are a resident, its much easier for you to critique the plan.

I am curious as to how those designed roundabouts will affect freight within the area.

The bicycle friendly additions provided by the project are a def. winner in my book, along with the proposed urban design that was detailed on the website.

J. Sparks said...

Thank you so much, Alan.

As for freight, truck traffic has been banned on Keystone since the state relinquished the roadway to Carmel in 2007.

The present infrastructure setup are as follows:

Prior to relinquishment, trucks were allowed to use Keystone, and many fatal accidents resulted from trucks running red lights. The all-red phase was 5 seconds.

The amount of traffic during rush-hour led to the road backing up severely between several intersections, particularly 116th St. and 106th St. These intersections are a little over a mile apart.

The signal timings were already long and exacerbating gridlock on cross-streets beyond the intersections with Keystone.

As for the need to do this project in the first place, as a state highway, the road was to be widened to a 6-lane facility with virtually zero changes made otherwise. This was planned to be done in preparation for the conversion of US-31, which bisects Carmel in half, from a similar expressway to a full-fledged, grade-separated freeway.

Carmel balked at the additional widening, alleging that it would become "The Great Wall of Carmel," so Carmel decided to negotiate for the relinquishment of the roadway so it could grade-separate it.

If you look at an aerial map, you'll see that Keystone is flanked with residential neighborhoods, several churches, a shopping mall, and one golf course. Carmel made its proposal to try to eliminate idling traffic on Keystone, noisy truck air brakes, and eliminate fatal collisions with cross-traffic. Finally, the primary goal of the interchanges is to make the crossings safer and more feasible for cyclists and pedestrians. Currently, no crosswalks exist for pedestrians, and cyclists have demarcated lanes on some streets intersecting Keystone, but not throughout the intersection itself.

Hope this helps, please let me know if you have any further questions.