Planning & Preliminary Engineering Subcommittee
July 23, 2004, 1:00 pm
Penn Stater Conference Hotel
State College, PA
Doug Harwood, Midwest Research Institute
Paul Ryus, Kittelson & Associates, Inc.
Erik Ruehr, VRPA Technologies
Scott Washburn, University of Florida
Fred Hall, McMaster University
Bob Foyle, North Carolina State University
Darren Torbic, Midwest Research Institute
Barbara Ostrom, MACTEC
Tom Raught, New Mexico DOT
Tom Creasey, American Consulting Engineers
Doug McLeod, Florida DOT
Martin Guttenplan, Florida DOT
Kevin St. Jacques, Wilbur Smith Associates
Bob Bryson, City of Milwaukee
Aimee Flannery, George Mason University
Bryson welcomed the group.
Harwood distributed ballots for rating priorities for (1) HCM improvement themes and
(2) research problem statements. He also distributed copies of the new/revised research
problem statements developed on Thursday. Ballots were to be collected at the full
committee meeting on Saturday.
No changes were noted to the January meeting minutes.
Bryson asked the group whether they’d prefer to get the minutes soon after the meeting
(when they’ve been available) or soon before the next meeting. Guttenplan suggested that
they be sent out at both times and Bryson concurred.
Status of proposed research on default values:
(Bryson) This research problem statement was selected by the committee and sponsored
by Wisconsin and Florida. SCOR ranked the problem statement as a very low priority,
but we were given a chance to provide a rebuttal to the review. WI, FL, and KY
intervened and the statement made it into the program, contingent on the availability of
funds. If funding is maintained at current levels, it won’t be funded. The reauthorization
package in Congress would increase funding levels. (Creasey) At some point, if
reauthorization doesn’t occur, the project wouldn’t be funded this year, but would remain
in the hopper.
Planning & Preliminary Engineering Applications for Freeway Facilities:
(Bryson) A research problem statement has been prepared by McLeod.
Planning & Preliminary Engineering Analysis of Oversaturated Conditions:
(Bryson) Ruehr has prepared a research problem statement. (Ruehr) The group yesterday
thought that it should be focused on regional values, but didn’t change the problem
statement—only offering as advice.
Signalized Intersection Quick Estimation Method:
(Bryson) We have been working with the signalized intersection subcommittee. It was
discussed this morning at their meeting, where it met with some resistance.
Future Directions of Planning and Preliminary Engineering in the HCM:
(Bryson) White paper found that although the goal was for each chapter to provide a
planning model, that hadn’t happened. Ruehr & Andy volunteered to develop an example
planning model for the unsignalized intersections chapter as an example.
(Ruehr) Unsignalized application was done for two-way stop-controlled intersections.
The ideal model recommended by the planning audit in July 2003 would give user 3
choices: operations analysis (user provides all input values), planning analysis (all inputs
defaulted), or customized analysis (user decides which inputs to provide).
(Bryson) When default values were first brought up, they were looked upon with scorn
because of concerns that default values would automatically become input values.
(Creasey) This works under our current procedure, in that there is only one procedure—
the difference is in how many default values are used.
(Ruehr) Based on feedback from July 2003, perhaps there should be a range of defaults.
The new model would provide three levels of planning analysis with high, medium, or
low capacity assumptions. I am working toward being able to support this—and am
almost there—many applications I come across are in new suburban locations and for
long-range (20-year) planning, where I’m looking for high capacity. Would hope that
HCM guidance wouldn’t automatically direct users to low or medium capacity. Presented
ideas for defining high, medium, and low capacity. There is more work needed to go this
route, but with funded research and volunteer efforts, who knows what’s possible?
(Bryson) One of the shortcomings of the signalized procedure when it was first modeled
was that ideal conditions were modeled. This resulted in dramatically different results—
the planning model predicted no problem whatsoever, while the operations model found
oversaturated conditions. We then went in the completely opposite direction by using
minimal conditions for the planning model, which wasn’t necessarily best, either. Ruehr’s
approach gives the user more latitude.
(Ruehr) In the low capacity scenario, you have to be a little careful—street widths could
be 12-foot high, 11-foot medium, 10-foot low, but what do you do about something like
grade? Would you assume a 6% grade?
(Creasey) Concerned that we’re introducing a layer of confusion for anyone except an
experienced user who knows what’s going on. Someone confronted with this may get
totally confused. The framework in principle is fine; how we present it to the user is
where we need to be careful. Keep the end-user in mind as we apply the framework.
(Ruehr) If we adopt this framework, there could be any number of customized defaults—
HCM high/med/low, City of Milwaukee high/med/low, etc.
(Washburn) Something we’ve done in the LOSPLAN programs is to provide a user
adjustment factor which scales your capacity which ever way you think is appropriate.
(Ostrom) The terms high capacity, medium capacity, low capacity scare me. Maybe build
(Bryson) The point is to provide more guidance than currently exists—to provide a range
of default values. Promote the idea that more than one value is possible to solve a
problem—it makes a better planning analysis if you know what the default value
(Torbic) Confused the same way about high/med/low. Suggest ideal/best-case scenario
and conservative scenario.
(Ruehr) Ideal also scares me—it’s what in my day-to-day practice I’d call typical.
(McLeod) My leaning would be to go to the more general presentation previously shown.
LOSPLAN specifies ranges.
(St. Jacques) Maybe a drill-down approach—provide more layers of defaults if needed.
For planning, I don’t want to deal with a bunch of definitions—I want a set of conditions
to pick from, with a corresponding set of defaults.
(Bryson) The original intent of default values was to provide identical results for the
planning method when the operations method was run using those inputs. It doesn’t work
for signalized intersections because of the simplifying assumptions built into the
operations model for left turns. The interchange ramp terminals group is developing a
separate planning application.
(Ruehr) Would like the subcommittee to make a decision on the type of procedure to
support, or to determine that it was an interesting idea, but that we should move on.
(Ostrom) Maybe the thing to do is to take a step back to define a planning application—
an application that uses the same or fewer inputs as the operations model, and that
produces results within one LOS grade. It could be a separate methodology.
(Bryson) A separate methodology would be different than what’s being proposed. I am
concerned about a public hearing where planning and operations methods give different
(Creasey) At the time the motion was adopted, we thought it would be easier to get full
committee acceptance, but at the same time there weren’t new procedures on the horizon.
Will interchange ramp terminals even produce LOS, or will it just be over/near/under
saturation? Perhaps our premise should be one method whenever possible, with a second
method if a subcommittee determines it’s necessary.
(McLeod) As much as possible, I think we should stay with default values and
simplifying assumptions. The heart of the HCM is the simple operations methodology.
Planning people need to be as consistent as possible with the simple operations method.
For the freeway methodology, FDOT was disappointed that we didn’t get a planning
method. We hired Elena Prassis to develop one—we weren’t able to get a method
perfectly aligned, but we were able to get one about 90% aligned—not perfect, but
consistent with the intent.
(Guttenplan) I get scared when I hear about different methdologies entirely. Will they
apply the same service measures? I have been applying planning methods for some time,
and have been trying to remain faithful.
(McLeod) Florida has been applying Elena’s method for a couple of years now and have
not had any substantial criticism come back.
(Bryson) To try to get consensus—use defaults and simplifying assumptions to the extent
possible and have procedures that get consistent results otherwise.
(Ruehr) What actions do we take to implement this?
(Creasey) Concerned that we don’t have the concept yet in a form that can be put on an
overhead for presentation to the committee.
(McLeod) I would have to go back to what I wrote, but I’m sure that I included
simplifying assumptions in the motion, recognizing that defaults weren’t always possible.
We shouldn’t need to go back to the committee. The intent was to get the exact-same
number, but this was not always possible—intent was to be close to the number.
(Creasey) We’re not solid altogether on this issue in this subcommittee, so I’m not
comfortable bringing it to the full committee yet. This could be presented in the group
(Ruehr) Couldn’t we put a slide with operations/planning/customized up for the
(Ostrom) Can we explain “customized” concisely?
(Ruehr) To me, the slide is very simple. If we can’t agree on this, it’s time to throw it
aside. Going into more details won’t solve this.
(Ostrom) I haven’t heard anything in terms of how defaults are selected, or what makes a
process such that it needs a simplifying assumption.
(Bryson) This was defined back in the late 1990s in terms of basic required inputs.
(Bryson) I agree a step back is necessary, but I still want to present the front slide to the
full committee in January. I will assemble material in the next month or so and distribute
it to the subcommittee and friends. Would a workshop be desirable/practical/necessary in
January? Maybe if we can reduce it to writing, a workshop isn’t necessary.
(Ostrom) It would be useful to refresh the committee’s memory—we’ve had complete
turnover since 1997.
(Bryson) Ruehr has made significant progress towards meeting the needs of Chapter 17.
(Bryson) Thanked persons for attending.
The meeting was adjourned at 2:30 pm.