The relationship between time mean speed and space mean speed that was derived by Wardrop and presented in several textbooks is suitable for estimating time mean speeds from space mean speeds. In most cases, however, estimating space mean speed from time mean speed measurements is desired. Consequently, a new formulation utilizes the variance about the time mean speed as opposed to the variance about the space mean speed for the estimation of space mean speeds. It is demonstrated that space mean speeds are estimated within a margin of error from 0% to 1%. Furthermore, a relationship is developed between the space and time mean speed variances and between the space mean speed and the spatial travel time variance.
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References
1.
WardropJ. G.Some Theoretical Aspects of Road Traffic Research.Proceedings of the Institute of Civil Engineers, Vol. 1–2, 1952, pp. 325–378.
2.
HobbsF. D., and RichardsonB. D.. Traffic Engineering, Vol. 1. Pergamon Press, 1967.
GarberN., and HoelL.. Traffic and Highway Engineering, 3rd ed.Brooks/Cole, 2002.
5.
HallF. L., and PersaudG. B.. Estimating Speeds from Freeway Traffic Management Systems.ITE 1988 Compendium of Technical Papers, Institute of Transportation Engineers, 1988, pp. 166–171.
6.
DaileyD. J.A Statistical Algorithm for Estimating Speed from Single-Loop Volume and Occupancy Measurements,Transportation Research, Vol. 33B, No. 5, 1999, pp. 313–322.
7.
LighthillM. J., and WhithamG. B.. On Kinematic Waves: A Theory of Traffic Flow on Long Crowded Roads.Proceedings of the Royal Society of London, Vol. 229, 1955, pp. 317–345.
8.
HellingaB.Improving Freeway Speed Estimates from Single-Loop Detectors.Journal of Transportation Engineering, Vol. 128, No. 1, 2002, pp. 58–67.
9.
WangY., and NihanL. N.. Can Single-Loop Detectors Do the Work of Dual-Loop Detectors?Journal of Transportation Engineering, Vol. 129, No. 2, 2003, pp. 169–176.
10.
LinW.-H., DahlgrenJ., and HuoH.. Enhancement of Vehicle Speed Estimation with Single Loop Detectors. In Transportation Research Record: Journal of the Transportation Research Board, No. 1870, Transportation Research Board of the National Academies, Washington, D.C., 2004, pp. 147–152.
11.
CoifmanB., DhoorjatyS., and LeeZ.. Estimating Median Velocity Instead of Mean Velocity at Single-Loop Detectors.Transportation Research, Vol. 11C, No. 3–4, 2003, pp. 211–222.
12.
WangY., and NihanN. L.. Freeway Traffic Speed Estimation with Single-Loop Outputs. In Transportation Research Record: Journal of the Transportation Research Board, No. 1727, TRB, National Research Council, Washington, D.C., 2000, pp. 120–126.
13.
CoifmanB.Improved Velocity Estimation Using Single-Loop Detectors.Transportation Research, Vol. 35A, No. 10, 2001, pp. 863–880.
14.
DaganzoC.Fundamentals of Transportation and Traffic Operations.Elsevier Science, 1997.
15.
CoifmanB., LyddyD., and SkabardonisA.. The Berkeley Highway Laboratory-Building on the I-880 Field Experiment.Proc., IEEE ITS Council Annual Meeting, IEEE, 2000, pp. 5–10.
16.
KhistyC. J., and LallB. K.. Transportation Engineering: An Introduction.Prentice Hall, Englewood Cliffs, N.J., 2003.
17.
PersaudB. N., and HurdleV. F.. Some New Data That Challenge Some Old Ideas About Speed-Flow Relationships. In Transportation Research Record 1194, TRB, National Research Council, Washington, D.C., 1988, pp. 191–198.
18.
HallF. L., and GunterM. A.. Further Analysis of the Flow-Concentration Relationship. In Transportation Research Record 1091, TRB, National Research Council, Washington, D.C., 1986, pp. 1–9.
19.
RossP.Some Properties of Macroscopic Traffic Models. In Transportation Research Record 1194, TRB, National Research Council, Washington, D.C., 1988, pp. 129–134.
