February 20


Mitigation Responsibilities

By Mike Spack

February 20, 2009

Bad pavement
Matt asked (paraphrased):

I have a 100 +/- unit residential development that is
proposed on a roadway that is in bad condition due to a public waterline
failing under it.  This road is 2 miles from a State Highway and is a major collector servicing
the south side of a community of about 3000.  In twenty years, about 20%
of the road's traffic will be generated by the residential development.  The County is requesting mitigation, with no specifics. 
They do not have impact fees, and the subdivision is in a City (annexed), so it
is the developer’s position that the County has no grounds for demanding
mitigation, but he wants to do what is right without “selling the farm”.  
The County’s stated concerns are based on “impacts” and Levels of Service.


What are your thoughts? I want my recommendations to be
consistent with ITE standards of practice, but can find little on how to
suggest equitable and reasonable mitigation for a few hundred cars a day on a
road that will have maybe 3000 ADT (vehicles per day) in 20 years! 
Obviously, congestion is NOT an issue!


projected Level of Service (LOS) for all impacted intersections is at or above
LOS C in the 20-year projection.  This impact lowers the 20-year projected
LOS from B to C (barely) for one movement at one intersection (left turns onto
a minor road from the State facility), Increasing the Traffic volume by 20%, and
addition of the 100+/- homes.  The County Capital Improvements Plan is not available (Not sure it exists) and this roadway is a
concern to them regardless of this development.  At the 20-year
projection, the State facility will meet guidelines for the addition of a left
turn lane at this location based on volumes with or without this development.


Considering 18-kip ESAL loading and a 20-year projection, the
subdivision will account for about 10% of the ESALs experienced by this
roadway.  This calculation was done to obtain some basis for a possible
strategy for working with the county on this issue.  It is looking like
the County wants the developer to contribute to the improvement of the roadway,
but will not state the amount of participation at this point.  It is also
becoming clear the “LOS” means the estimation of how many phone calls the Road
Department is going to receive, not operations/calculations based.  This
is difficult to analyze or address to say the least.)


Here is my response:

I have not seen any ITE (Institute of Transportation Engineers) recommendations on mitigation.  I
am sure ITE steers clear from this area because it is so situational. 
What is considered acceptable is very local – standards in Los Angeles are different than Minneapolis which are different than Boise.


I was involved in a case where a city was trying to assess a
150 lot subdivision for improvements to a highway/county road intersection two
miles away.  The developer and the local builders association fought it in
court.  The case was quickly dismissed.  The judge ruled the
assessments were unreasonable based on Minnesota law.  There is always a pain threshold where lawyers should be brought in
if a jurisdiction pushes too hard.  I personally don't take hard line
positions on these types of issues, since they are more politics than


I don’t have any silver bullets for you on this one.  It
would seem prudent to me that the county put the road improvement in their
capital improvement plan (which should have a category of improvements based on
road conditions) and then assess the adjacent properties accordingly based on
abutting linear footage.  That way the adjacent property owners pay
proportionally for the benefit.  I am not sure if counties have assessment
capabilities in your part of the country or not.  Based on your
description, it sounds like the road should be a city street not a county road.


Any other advice out there?



  • Florida Statutes has a formula for calculating a projects “fair share” of a roadway improvement that might help in this situation. It’s simply the project traffic divided by the capacity created by the improvement multiplied by the project cost. It sounds like this would be a reconstruction of an existing road, without the additional capacity (depending on if that left turn lane is included in the design). So in this case, it would be simply the project traffic divded by the overall capacity of the road times the project cost.
    It’s not the best method in the world, however, it’s been used here for many years and it allows the local governments to put a price tag on a project’s impacts.

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    Mike Spack

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