We are planning a project to upgrade the low water crossing on McNeil Drive near north Mopac.

Background

The low water crossing on McNeil Drive passes over "Tributary 9" of Walnut Creek. The low water crossing has been closed 22 times between 2014 and 2018. Computer models show three feet of water over the road in a relatively small storm, known as a 2-year storm. This type of storm has a 50% chance of occurring in any given year. In a 100-year storm, or one that has a one percent change of occurring in any given year, the road will be overtopped by more than four and half feet of water.

Location

The low water crossing is on McNeil Drive, just west of MoPac. Please see map below.

map showing low water crossing

Proposal

The preliminary engineering report recommends replacing the low water crossing wtih a 300 foot long bridge with piers every 60 feet. At its highest, the bridge would be 12 feet over the bottom of the creek. The report recommends that the bridge has two lanes for vehicles and two shared use lanes for bikes and pedestrians.

Graphic showing proposed bridge and its approach

Timeline and Cost

Our capital improvement projects take many years from start to finish. The process typically includes the following phases:

  • Preliminary Engineering – when a solution is identified and costs are estimated.
  • Design and Permitting – when the details are worked out, construction plans are drawn up and the permit to perform the work is obtained.
  • Bidding and Permitting – when a contractor is hired
  • Construction – when the project is built.

We completed the preliminary engineering phase in the spring of 2019 and are hoping to begin the design phase over the summer of 2019. If all goes well with the design and permitting, construction is anticipated to begin in 2021. The estimated cost is between $5.4 and $6.2 million, but that cost will be refined as the design proceeds.

Documents

Questions

For more information, please call John Middleton, P.E., at 512-974-3515 or send John an email.