Interesting results have come from the use of rubber paving tiles for almost seven yenrs on the Michigan Avenue lift bridge in Chicago. The upper level of this bridge carries an average daily traffic of 60,000 automobiles and buses, Pavement wear under such severe conditions is aggravated deeause traffic lights at each end of the bridge necessitate frequent starting and stopping on the structure. The original pavement of this bridge Was wood block: and proved too slippery. After investigntion of rubber pavements elsewhere, an experimental quarter section was laid, axing patented G-In. x 12in. rubber tiles, Lain, thick, at a cost of $1.30 per square foot. After a year of observation the maining three-fourths of the surface was similarly paved, with some improvement in design and methods of fastening, 1927, chafing and slippage of the under blocking necessitated removal of the original tiles and repaving with tiles 1d-ins, thick, at & cent of $1.50 per square foot. Move ment of the blocks still tends to pry them loco, and maintenance costs are high.
When new, the blocks were skidproof, but with wear and coating with all and grease, they have become slippery. The experiments, however, are still being carried on
Text read from the printed page and cleaned; old type leaves the occasional error.