When was the sidewalk invented

The autocratic, self-styled Baron Haussmann his title was never officially sanctioned enjoyed almost limitless power and influence over the redesign of the city.

Under his patron Napoleon III, he tore down the cramped, dark streets of medieval Paris and replaced them with wide, light-filled boulevards and block upon block of nearly identical apartment buildings with uniform facades. Flanking the grand boulevards were—you guessed it—sidewalks. But these were no ordinary sidewalks. They were the perfect stomping-ground for bourgeois Parisians, who turned up to stroll and mingle in droves.

From little more than open sewers, city streets were transformed into places to see and be seen among the fashionable elite, redefining the experience of urban life in the process. Haussmann widened and illuminated the streets of Paris, and these boulevards were framed with sidewalks, benches, and vegetation. With the eradication of medieval Europe's filthy roads and public health concerns, Paris sidewalks became the meeting places for elite Parisians. However, Haussman's spending may have been too indulgent because he fell from grace with Napoleon III in , but his contribution wasn't in vain.

His model of infrastructure was soon adopted by officials in the United States, Barcelona, and Vienna. Sidewalks became common in urban areas in the 19th century, and business owners often funded their construction. Sidewalks supported commerce as street merchants and shopkeepers showed off their wares next to the road, and they also encouraged the spread of ideas and current events.

Table 2. From a Goodyear publication, the following quote may be of interest []:Wheels continued to evolve. In the early s, Goodyear discovered the hot vulcanization of rubber which made it possible to manufacture solid rubber tires [Collins and Hart, ]. The impact of rubber tires can be illustrated by English law.

The pneumatic tire was patented in the U. The earliest pneumatic tires had major shortcomings in strength and durability [Goodyear Tire and Rubber Company, ]. John Dunlap, U. The first pneumatic tire used on a motor vehicle was in in a race from Paris to Bordeaux [Goodyear Tire and Rubber Company, ]. Of course, there were trucks before then, but virtually all trucking was confined to intercity hauling because of the solid tires of the day which gave a bone-rattling ride and consequent slow speeds.

All of this came about because Goodyear was fighting to prove the value of pneumatic tires for trucks. An early effort to examine tire contact pressures was provided by Eckels in a paper. Measurements were made on solid rubber, cushion and pneumatic tires.

The solid rubber tires had measured contact pressures up to kPa. The pneumatic tires had contact pressures of about to kPa for a tire inflation pressure of kPa. Data summarized by Baron [] for aircraft in the early s suggests inflation pressures of no more than to kPa.

As is illustrated by the Public Roads Administration in , the traffic input into the evolving pavement design procedures of the day varied. This included the use of wheel load magnitudes ranging to the early concept of equivalent wheel loads. Hveem and Carmany in a paper showed that the thickness of surfacing and base was proportional to the tire pressure and the number of load applications. Traffic was characterized in the proposed California thickness design procedure by the following term:.

This concept evolved into equivalent wheel loads. This work was based on the relative destructive effects of wheel load groups ranging from 20 to 42 kN to lb. Equivalent Wheel Load EWL constants were developed to more easily summarize the available truck traffic classified by the number of axles. Hveem and Carmany [] found the term 6 log EWL could replace in their thickness design equation. A variety of equivalency factors can be used depending on the pavement section which is defined by a Structural Number and the terminal serviceability index for flexible pavements.

Some of the earliest recorded information about materials which could be and were used in pavements concern hydraulic cement and the Romans; however, in fairness, the earliest known use of hydraulic lime was in Syria about 6, B. The first known use of hydraulic cement by the Romans occurred at about B. Further, the Romans learned a bit about the use of other additives such as blood, lard and milk. Apparently, blood hemoglobin actually is an effective air-entraining agent and plasticizer given the mild Mediterranean climate the primary use was likely for workability.

Some of the early paving materials have been previously discussed; however, it might be interesting to compare a few prices.

To adjust these costs to contemporary prices one must multiply by at least a factor of ten. Note: original asphalt prices from Byrne in Louis bridge had a compressive strength of 8. Other compressive strengths he reported presumably pres ranged from 1. Compare these results to contemporary compressive strengths of Thus, in years, PCC strength has increased about times ratio of extreme low to extreme high.

Byrne also provided some cost data on wood block pavements in London. This roughly translates to about 2,, metric tons of equivalent hot mix or about three times the annual amount of hot mix purchased by WSDOT. Material characterization up to the s tended to focus on basic material parameters such as liquid limit, plasticity index and gradation.

The strength or bearing capacity of unstabilized materials was usually discussed in terms of cohesion and friction angle as illustrated by Collins and Hart, The recommended test was to use a bearing block directly on a compacted sample. The test result was a plot of bearing stress versus indentation of the block into the sample. An indentation of The papers by Burggraf in , , and summarized the results of extensive field shear tests made on flexible pavement layers.

These shear tests were conducted with a small, portable apparatus which used a parabolic plate in contact with the soil being tested []. As an illustration of the results from this test, the measured shear strength of cohesive subgrade soils were evaluated beneath stabilized base courses. The following classes were reported []:. Work by Hubbard and Field [] for The Asphalt Institute tended to downplay the importance of subgrade bearing values, and instead, emphasized the importance of surface deflection testing as a way to characterize the overall pavement structure.

And soon enough, almost all of the urban cities across the globe took the idea of transforming their city streets into spaces safe for pedestrian locomotion as well as a place for leisure and consumption, adding to the quality and luxury of the urban life. Your email address will not be published.

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