How Many Engineers Does It Take to Count a Roundabout?

UNIVERSITY OF MISSOURI-COLUMBIA

Carlos Sun, Ph.D., P.E.

Counting Traffic is Easy, Right?

Introduction

Conservation equations

Hardware

Software/Algorithm

A Discussion of Automated Roundabout Counting:

Quick Bio• The road to traffic nerdom

– Start as electrical engineer in 1990• hardware/software

– Studied transportation engineering at UCI– ITS research at California PATH– 11 years teaching transportation, 8 at Mizzou

Roundabouts in the U.S.• Roundabout is one tool in a panoply of

solutions for intersections

• Modern roundabout: Las Vegas, 1990

• Increasing use, ~2000 as of January 2009 (RoundaboutsUSA)– 20k in France, 15k in Australia, 10k in the UK

• More and more roundabouts need to be counted and studied-> job security, yeah!

Magic Roundabout, Swindon, UK6 approaches/departures, 1 big and 5 kiddie roundabouts

Magic Roundabout:

Conservation Equations

Conservation Equations (FHWA): 4 Legged Roundabout

• 4x4=16 movements• 2x4=8 count

locations• Underspecified

problem

Conservation Equations: 4 Legged Roundabout

• But wait, if we neglect u-turns:– 12 movements– 12 counts: 8 entry/exit counts

+ 4 circulating

• Problem solved?

Gauss and Jordan say: Denied• Not linearly

independent– It’s still underspecified

• We need to count specifically: – right turns, or left turns,

or through movements– but at entry point, not

know which way a vehicle will end up!

1 0 0 0 0 0 0 0 0 0 0 -1

0 1 0 0 -1 0 0 1 0 0 -1 0

0 0 1 0 1 0 0 -1 0 0 1 1

0 0 0 1 1 0 0 -1 0 0 1 1

0 0 0 0 0 1 0 1 0 0 -1 -1

0 0 0 0 0 0 1 1 0 0 -1 -1

0 0 0 0 0 0 0 0 1 0 1 1

0 0 0 0 0 0 0 0 0 1 1 1

0 0 0 0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 0 0 0 0 0

Hardware

Video Field of View• Apart from using cellular, bluetooth, or

other AVI-type tracking

• What are some achievable fields-of-view?

Halls Ferry, STL

Creasy Spring, Columbia

Bearfield, Columbia

Waldenmaier (NCHRP 572)

Camera Mounting

Tripods, e.g. miovisionPole mount, e.g. Russell

Trailer, e.g. MU

Mirror

NCHRP 572

Remote Reality

Elliptical Dome, MU

Software/Algorithms

Count Estimation Systems, e.g. Eisenman and List

• Additional spec. w/Time stamps

• Count entrance, exits, circulating

• Assume FIFO

• Estimate turning movements

Other Estimation Procedures• Bi-Proportional: log-linear model (Van

Zuylen & Willumsen, Bell, Nihan & Davis, Hellinga)

• Algebraic Solution: rights turns (Robinson, Rodegerts et al.)

• Sequential Quadratic: constrained least squares (Cremer & Keller, Ashok, Dixon & Rilett)

• Factored Survey: surveys (Dixon)

Time Series Method

Virtual Loop Time Series, MU

Following Different Movements

• Differentiating b/t:– Circulating– Entering– Exiting

• Augment measured variables– Not longer

underspecified

• Problem w/tailgating

Tracking Systems

Tracking Type Systems, e.g. miovision

Common Tracking Algorithms (Coifman & Malik)

• Model-based – detailed geometric object models

• Region-based – connected region, “blob”

• Contour-based – reduce to boundary

• Feature-based – distinguishable pts., corners– Group rigid features moving together

Algorithm Step Examples

• Vehicle image capture• Background subtraction• Gradient/edge detection• Feature vectors• Inter vs. intra cluster movement

Feature-Based Tracking

Multi-Detector Control

Multiple Cameras, e.g. Autoscope• Junction control • 8 cameras• 31 counting stations• 5000 vph• Krakow, Poland• No turning movements

necessarily

So how many engineers does it take to count a roundabout?

Assign a person to count each approach? (e.g. 4 persons for a 4-legged RA)

Have an engineer design an automated system

(e.g. HAL 9000)

Questions/Comments?FOR MORE INFORMATION

PLEASE CONTACT:

CARLOS SUN

UNIVERSITY OF MISSOURI

csun@missouri.eduFeasibility of an Automated Solution for Deriving Roundabout

Turning Movements; Rescot, Sun; TRB 2008 Paper #08-0388

Automated Capturing of Roundabout Turning Movement Counts; 2008 National Roundabout Conference

http://www.teachamerica.com/RAB08/ListMenu.html