50' Box Culvert

Click picture to enlarge.

This is a picture of a 50' box culvert. Using a culvert of this width would allow both the wetlands and a slightly elevated pedestrian trail to use the same under-crossing. The advantage of this culvert is increased visibility and hopefully less crime as a result.

Click picture to enlarge.

This document shows 2008 cost estimates for a 50' box culvert. In comparing 2008 estimates for the two separate culverts vs. the 50' box culvert, there is less than a $200,000 difference. The two separate culverts (estimated with retaining walls) were projected to cost $1.2 million. The 50' box culvert (also estimated with retaining walls) was projected to cost $1.4 million. In reality costs have decreased since these estimates. The city has already secured fill for significantly less than estimated above. Also, we would prefer a 1:3 landscaped slope instead of retaining walls which would further reduce each estimate by about $400,000.

Cost for Two 20' Culverts

This is a rough illustration of two separate culverts crossing under 1120 North. One culvert would contain the wetlands, the other a pedestrian trail. This illustration shows retaining walls. We have indicated a preference instead for 3:1 landscaped slope sides.



This document shows estimated cost for placing two culverts and completing the road. This is based on 2008 estimates. Also, this estimate includes retaining walls. We have explored the option of using landscaped 3:1 sloped sides instead to maintain the feel of the hollow.

This is a current (late 2009) cost analysis which includes placement of two culverts (bottom - in pink). This cost does not include completion of the road above. In orange, I believe, is the cost of a single trail crossing over the road. On top (in yellow), the cost estimate is for two culverts and a retaining wall instead of sloped sides.

These current costs are significantly less than 2008 estimates because of a reduction in costs generally because of the slowing economy. Also, the city has already acquired fill at a reduced price from prior estimates. Again, this sheet of 2009 estimates does NOT include the costs of completing the road, while the 2008 estimates do.

Report on April 28 Meeting

Last night at our neighborhood meeting regarding the Mitchell Hollow Crossing, we had a good attendance by many of the familiar faces from this project. There was also a handful of neighbors who were new to these discussions. They primarily came from homes that are immediate adjacent to the portion of Mitchell Hollow below 1120 North. Jim Price (MAG - trails) came and talked to us about pros and cons of at-grade crossings verses under-crossings. He suggested that an at-grade crossing at this location (mid-block on a major collector) would actually be much more dangerous than an under-crossing.

So, as per Jim's comments as well as both neighborhood's feelings, we have decided that we do not want the at-grade crossing as currently proposed by the city. We would prefer a single 50' box culvert that contains both the wet area and the trails. We are currently trying to put a proposal together that shows that a single culvert is not much more expensive than two separate 20' culverts (yet significantly increases visibility). We are also trying to get on a work-session agenda so we can make this presentation to the city.

We realize that there might not be any immediate funding available for this project. We are hopeful for possible MAG funds in five years to help make this area fabulous. But in the meanwhile, we would like to get the city council and staff on board in thinking and planning ahead for a 50' box culvert.

Which Do You Prefer?

There are several proposals on the table for the design of the trails at Mitchell Hollow Crossing. Please email us at afroads (at) gmail (dot) com to let us know which of these options you prefer and why!

Here is a brief explanation of each:

Trail crosses over 1120 North.
This is the current design proposed by American Fork city staff. Pictures and diagrams can be found on a previous post here. The main trail would travel along the west ridge of Mitchell Hollow. The trail would cross at a crosswalk on 1120 North as it nears 900 West. The city has proposed a pedestrian-activated crossing light at this location. The wetlands would pass under the road in a culvert.

Trail passes under 1120 North through a culvert.
Two culverts (10' tall x 20' wide) would be installed to pass under 1120 North. One would contain the designated wet-land areas. The other would be for pedestrian traffic. [Also being discussed: 1) One single culvert to contain both pedestrian traffic and wet-lands. 2) Enlarging the culvert designed for pedestrian traffic.]

Other.
There has been some discussion of placing a large bridge but this has been deemed too cost-prohibitive. There has also been discussion of placing water lines only, but the city has indicated that maintenance would be too difficult.

Original Park Design

This is an original concept design for Hunter Park. Click to see a larger image. Note the location of the planned trails. This concept design used culverts for the wetlands, pedestrian and equestrian trails to pass under the road. Trails for equestrian and pedestrian use are separated. The pedestrian trail passes through the culvert designated for wet-lands using board walks.

Road Design

1120 North has been designated as a Major Collector (82 feet). As 1120 nears 900 West, it will narrow to around 64 feet. AF city plans to eliminate the sidewalk and buffer on the side of the Lehi retention pond.

Please Send Your Suggestions!

We would like to put ALL ideas on the table as we discuss the future design of Mitchell Hollow Crossing at 1120 North. If you have thoughts or ideas on the trail design, road design and/or water-way design, we would like to hear your ideas. We invite you to send your thoughts to us at afroads (at) gmail (dot) com. Please respond before April 20.

We would also encourage you to send your ideas to the Mayor and City Council. Their contact information can be found here: http://www.afcity.org/Government/CityCouncil/tabid/86/Default.aspx