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Ground Plan

track, feet, tangents, curves, tracks and circular

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GROUND PLAN. The following principles must be borne in mind in designing the ground plan of a bicycle race-track.

1. The length and the form of the track will depend upon the size and the shape of the area available.

2. Large tracks are expensive to construct, and do not afford the spectators as good a view of the races as smaller tracks. Very small tracks are objectionable because of the sharp curvature and consequent high banking required.

3. For convenience it is desirable that the length of the track shall be an aliquot part of a mile.* 4. The field should not be so wide that the spectators are unable to see easily all parts of the race.

5. It is desirable that there should be enough straight track upon which to start the race.

6. The curves should be of such form that the rider experiences no lurch due to a change of direction in following the curve.

7. On curves a super-elevation of the outer edge is required, while on tangents none is required; and since this super-elevation can not be effected instantly, a varying curvature should be used to permit the joining of the flat tangents with the fully-banked curves.

The conditions which best meet the first four requirements can be determined only by experience, while the conditions meeting the remainder can be determined only by mathematical analysis It is proposed to describe the more noted tracks with a view of determining the present status of the best practice, and then to design a track which shall fully meet all of the above requirements.

Present Practice.

The first tracks were very crudely laid out. For example, it is stated that the curves of one of the earliest tracks in this country, the half-mile track at Hampden Park, Springfield, Mass., were located by running a bicycle over the ground and staking out the trail. Most of the early tracks were semicircles connected by tangents. Among these are the ones at Waltham, Mass., and Louisville, Ky. Each is one third of a mile in length with semicircles of 150 feet radius and tangents 409 feet long. These tracks have each held many world's records, and were for a time very popular.

The Charles River track, Boston, Mass., is one third of a mile in length, the circular curves being joined to the tangents by ease ment curves consisting of compound circular arcs. This track is a later design by the designer of the Waltham track, and may be considered as proving, in the mind of the designer at least, the im portance of joining the tangents and the curves by arcs of varying radii.

The track at Manhattan Beach, Long Island, N. Y., constructed in 1896,* seems to have been the first attempt to meet scientifi cally requirements 6 and 7 of § 992. This track is one third of a mile in length, and consists of two tangents connected by "elliptical curves " to circular arcs—see Fig. 166, page 635. Apparently the "elliptical curve," A B, consists of a series of nine circular arcs, each 6° long, having radii ranging in length from 144 to 212 feet. The circular arc, B C, is 38° 17' long, and has a radius of 136 feet. The tangents are 373.47 feet long, the "elliptical curves " 162.4 feet, and the circular arcs 181.76 feet. The track is 26.5 feet wide, ex cept the home-stretch, which is 40 feet,—the widest track in this country.

In 1896 a one-half mile track was constructed by the West Park Board in Garfield Park, Chicago.t Fig. 167, page 636, shows the ground plan of this track. The tangents are 376.5 feet long and are connected by semicircles having a radius of 300.32 feet. The width is 25 feet, except upon the home-stretch, where it is 35 feet. The widening of the home-stretch was accomplished by moving the center of the semicicular arc for the outside of the track 10 feet toward the home-stretch.

In 1897 a quarter-mile track was constructed at Racine, Wis., of the same ground plan as the Manhattan track except that the tangents were shortened and a higher banking was used.* These examples represent the most advanced theory of the form of bicycle-race tracks, since almost all others have been built by carpenters or professional riders without reference to the princi ples involved.

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