Netherland Inn Bridge Closure
Path Forward ?
Outcome Value
Outcome Risk
Case Paths
Case 1a (city) 2006           none       $600,000*     park/historic          low         low        6
Traffic   Sewer     Financial    ROW               Predict    Invest    Score
Case 1b (tdot) 2008        $500,000    $600,000*     displace home       low      medium     8
*includes $600,000 = 20% local share of estimated $3 million project
Case 1c (tdot) 2005        $500,000    $600,000*     displace home       high     medium     6
Case 2a (city) 2002            none      $1,100,000*   park/historic         low      medium      8
Case 2b (tdot) 2002-06   $500,000    $1,100,000*   displace home       low        high       10
 2008
Case 2c (tdot) 2002-03   $500,000    $1,100,000*   displace home       high        high       6
 2005
No
Repairs
Repairs
Given the complexity of the issues and possible outcomes, Public Works staff developed this chart to better illustrate the value and risks associated with each prospective outcome.  The intent of this process is to facilitate the identification of the most beneficial outcome – which should equate with that outcome that has the greatest value and lowest acceptable risk.

The value of the outcomes is measured by the same criteria originally used to develop a strategy for comment on the original TDOT bridge design which include:  traffic/community impacts, sewer costs, financial costs (in addition to the sewer), and right-of-way impacts.

The first criteria of risk of the outcomes is the “predictability” of each case – which is defined as the extent to which the City can either control an outcome or have confidence that subsequent decisions outside their control will occur as desired.

The second criteria is the level of investment required to realize an outcome – which is related to the financial requirements of either constructing a temporary sewer and making bridge repairs (in addition to the estimated $600,000 City share contribution required for the $3 million new bridge under the terms of the Federal Bridge Replacement Program).

The case score is based upon a risk rating with 1 = low and 10 = high.  The higher the score, the higher the assessed risk level.  The score was derived using numerical equivalents for the categories of low, medium and high.  For “predictability” low = 5, medium = 3, and high = 1, using the basis that the lower the predictability the higher the risk for the City.  Conversely, for “investment”, low = 1, medium = 3, and high = 4, using the basis that the higher the investment the greater the financial exposure and risk for the City.

Each case was analyzed across the outcome value and risk factors.  For the “traffic/community impacts” column the dates listed reflect when the bridge would be re-opened (either permanently or temporarily for certain cases) to traffic.  For the “sewer” column the cases were rated based upon whether or not a temporary sewer @ $500,000 was required to be built during the construction of the new bridge.  The “financial” column includes the estimated $600,000 (20% local contribution) to the replacement bridge and any repair costs for each respective case.  Lastly, the right-of-way (“ROW”) column lists the impacts of the different cases – with the realignment option requiring the use of portions of the parking area and bluff for the Riverfront Park and approximately 20’ of Rotherwood Mansion property, and the TDOT alignment requiring taking an occupied home of a family and relocating them.

In summary, the chart suggests that the most beneficial outcome is Case 2a – as it has the bridge re-opened for traffic in late 2002 and remains open until a new re-aligned bridge is built next to it, which also saves the City an estimated $500,000 in sewer costs and has by far the least community wide traffic impacts.  However, this option requires decisions that are beyond the City’s control so the risk rating is fairly high.  Conversely, Case 1c has the lowest combination of risk but it does not provide the outcome value of some of the other cases.

The challenge for the City is to see if there are ways of either reducing the risk for Case 2a or improving the value of Case 1c.