• The Mathematical Contest in Modeling (COMAP's site for the competition)

• Results of previous Mathematical Contests in Modeling

• The 2000 Mathematical Contest in Modeling

• The 1999 Mathematical Contest in Modeling

• The 1998 Mathematical Contest in Modeling

The Mathematical Contest in Modeling is an annual event, sponsored by the Consortium for Mathematics and Its Applications, in which students at colleges and universities all over the world are asked to develop and analyze mathematical models of open-ended, practical problems for which no direct solutions are known. Participants work in teams of three and are permitted to use libraries, computers, and other inanimate sources of knowledge and inspiration. The organizers of the contest propose three problems; over the three days of the contest, each team selects one of these problems, designs, implements, and analyzes a model, and writes a substantial report presenting its results.

The seventeenth Mathematical Contest in Modeling was held on February 9-12, 2001. Grinnell's teams this year were:

- Rachel Heck 2001, Andrew Kensler 2001, and Eric Nana Otoo 2001 (faculty sponsor: Marc Chamberland).
- Nathan Corvino 2001, Dolph Robb 2001, and Ari MacKinnon 2002 (faculty sponsor: Marc Chamberland).
- Paul Carlson 2002, Rackham Hoke 2001, and Ming Gu 2003 (faculty sponsor: Mark Montgomery).
- Tiffany Brunk 2002, David McClelland 2003, and Brandon Olsen 2001 (faculty sponsor: Mark Montgomery).

Here are the problems that COMAP posed this year:

Cyclists have different types of wheels they can use on their bicycles. The two basic types of wheels are those constructed using wire spokes and those constructed of a solid disk (see Figure 1) The spoked wheels are lighter, but the solid wheels are more aerodynamic. A solid wheel is never used on the front for a road race but can be used on the rear of the bike.

Figure 1: A solid wheel is shown on the left and a spoked wheel is shown on the right.

Professional cyclists look at a racecourse and make an educated guess as to what kind of wheels should be used. The decision is based on the number and steepness of the hills, the weather, wind speed, the competition, and other considerations. The director sportif of your favorite team would like to have a better system in place and has asked your team for information to help determine what kind of wheel should be used for a given course.

The director sportif needs specific information to help make a decision and has asked your team to accomplish the tasks listed below. For each of the tasks assume that the same spoked wheel will always be used on the front but there is a choice of wheels for the rear.

**Task 1.**Provide a table giving the wind speed at which the power required for a solid rear wheel is less than for a spoked rear wheel. The table should include the wind speeds for different road grades starting from zero percent to ten percent in one percent increments. (Road grade is defined to be the ratio of the total rise of a hill divided by the length of the road. If the hill is viewed as a triangle, the grade is the sine of the angle at the bottom of the hill.) A rider starts at the bottom of the hill at a speed of 45 kph, and the deceleration of the rider is proportional to the road grade. A rider will lose about 8 kph for a five percent grade over 100 meters.**Task 2.**Provide an example of how the table could be used for a specific time trial course.**Task 3**. Determine if the table is an adequate means for deciding on the wheel configuration and offer other suggestions as to how to make this decision.

Evacuating the coast of South Carolina ahead of the predicted landfall of Hurricane Floyd in 1999 led to a monumental traffic jam. Traffic slowed to a standstill on Interstate I-26, which is the principal route going inland from Charleston to the relatively safe haven of Columbia in the center of the state. What is normally an easy two-hour drive took up to 18 hours to complete. Many cars simply ran out of gas along the way. Fortunately, Floyd turned north and spared the state this time, but the public outcry is forcing state officials to find ways to avoid a repeat of this traffic nightmare.

The principal proposal put forth to deal with this problem is the reversal of traffic on I-26, so that both sides, including the coastal-bound lanes, have traffic headed inland from Charleston to Columbia. Plans to carry this out have been prepared (and posted on the Web) by the South Carolina Emergency Preparedness Division. Traffic reversal on principal roads leading inland from Myrtle Beach and Hilton Head is also planned.

A simplified map of South Carolina is shown. Charleston has approximately 500,000 people, Myrtle Beach has about 200,000 people, and another 250,000 people are spread out along the rest of the coastal strip. (More accurate data, if sought, are widely available.)

The interstates have two lanes of traffic in each direction except in the metropolitan areas where they have three. Columbia, another metro area of around 500,000 people, does not have sufficient hotel space to accommodate the evacuees (including some coming from farther north by other routes), so some traffic continues outbound on I-26 towards Spartanburg; on I-77 north to Charlotte; and on I-20 east to Atlanta. In 1999, traffic leaving Columbia going northwest was moving only very slowly. Construct a model for the problem to investigate what strategies may reduce the congestion observed in 1999. Here are the questions that need to be addressed:

Under what conditions does the plan for turning the two coastal-bound lanes of I-26 into two lanes of Columbia-bound traffic, essentially turning the entire I-26 into one-way traffic, significantly improve evacuation traffic flow?

In 1999, the simultaneous evacuation of the state's entire coastal region was ordered. Would the evacuation traffic flow improve under an alternative strategy that staggers the evacuation, perhaps county-by-county over some time period consistent with the pattern of how hurricanes affect the coast?

Several smaller highways besides I-26 extend inland from the coast. Under what conditions would it improve evacuation flow to turn around traffic on these?

What effect would it have on evacuation flow to establish more temporary shelters in Columbia, to reduce the traffic leaving Columbia?

In 1999, many families leaving the coast brought along their boats, campers, and motor homes. Many drove all of their cars. Under what conditions should there be restrictions on vehicle types or numbers of vehicles brought in order to guarantee timely evacuation?

It has been suggested that in 1999 some of the coastal residents of Georgia and Florida, who were fleeing the earlier predicted landfalls of Hurricane Floyd to the south, came up I-95 and compounded the traffic problems. How big an impact can they have on the evacuation traffic flow?

Clearly identify what measures of performance are used to compare strategies.

**Required:** Prepare a short newspaper article, not to exceed two
pages, explaining the results and conclusions of your study to the public.

Both the team of Rachel Heck, Andrew Kensler, and Eric Nana Otoo and the team of Nathan Corvino, Dolph Robb, and Ari MacKinnon earned the rating of Honorable Mention from COMAP's judges. Both the team of Paul Carlson, Rackham Hoke, and Ming Gu and the team of Tiffany Brunk, David McClelland, and Brandon Olsen were ranked as Successful Participants.

This year, 496 teams submitted complete entries. Nine of these entries were judged Outstanding; seventy, Meritorious. One hundred twenty-three received Honorable Mentions in COMAP's report. The remaining 294 teams were classified as Successful Participants.

This document is available on the World Wide Web as

http://www.math.grinnell.edu/mcm-2001.xhtml