Roadmaking Methods Are Right in the Reich
Page 49
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EAVING London to attend the LA Munich Road-making Exhibition, 1938, no one could have had the slightest inkling that Munich was to be the scene of one of the most momentous meetings in modern history. Dramatic, too, was the situation at the dinner given on the eve of the Exhibition, to a British delegation of road engineers. After a telegram had been received, recalling the delegates, a tense atmosphere pervaded the assembly and a pall of gloom descended on the proceedings.
Peace Changes the Scene.
Then came the startling announcement—the almost overwhelmingly glad tidings—that our Prime Minister had decided to fly to Munich on the morrow to confer with Herr Hitler at Obersalzberg. The uncomfortable tension relaxed and those present leaned back in their seats with feelings of relief. So it is no exaggeration to state that Mr. Chamberlain saved the Munich Road Making Exhibition, 1938, if one may be permitted to mention this achievement in the same breath with the far-more-important issues then at stake.
Those interested in commercial vehicles and road transport will, of course, have read—many times in The Commercial Motor—about the new German motor roads, the Reichsautobahnen. This Exhibition was devoted mainly to the machines used in the construction of these wonderful motorways, and it may interest readers to know something of the methods employed, as illustrated by the latest types of road-making machinery on show at Munich.
The Reichsautobahnen consist of dual carriageways, each 7.5 metres (24 ft. 7 ins.) wide, not including sidestrips, each 1 metre wide, on the outside edges. Where the surface of the carriageway is of concrete, i!e., white, the side-strip is finished black to provide contrast and to act as a guide in foggy weather and on dark nights. Alternatively, the side-strip is topped with concrete, where the carriageway is surfaced black.
In case of breakdown, one must
propel the vehicle as far over on to the side-strip as possible and must not stand on the carriageway. Of course, neither cyclists nor pedestrians are allowed on these motor roads.
Now a word as to the methods and the machines used in the construction. The soil is excavated either by means of scoops mounted on chain tracks, or by hand, where the work is easy, and is disposed in the direction necessary, according to the formation of the ground, by means of conveyor belts, each with its own power unit. When it is desired to transport the excavated soil over a long distance, this is effected by means of small Diesel or Diesel-electric locomotives.
The surface of the soil foundation is then levelled and consolidated with powerful rammers, some of which, although weighing over a ton each, can be handled by one man. Most of them are driven by oil engines, and these can also be used for driving other plant, such as pumps, when the rammers are not in action.
The side-strips are then laid by a
concrete mixer of to I cubic yd. capacity. At this stage, these strips serve a dual purpose, that of alignment and support for the rails on which will run the larger machines used for surfacing the carriageway. These form a complete train, consisting usually of about six machines, all of which travel under their own power.
The Mixing "Bridges."
First come the mixers, capable of turning out 50 mixes per hour, each mix consisting of approximately two cubic yds. These are constructed in the shape of bridges over the road, with the mixer drums at the top central position. Following these, come the distributor carriages with travelling hoppers mounted on rails, which receive the mixed concrete from under the mixer drums and place it evenly over the surface of the carriageway.
Both these types of machine, and indeed most of the plant used in the construction of the Reichsautobahnen, are driven by oil engines. Each mixer has a 40-50 h.p. motor and each distributor one of 18 h.p.
Finally come the finishing machines, which may be either tampers or vibrators, or both ; these machines, again, travel on the rails under their own power.
All the above machines have reverse gears and differentials and they can attain speeds of 10-15 m.p.h. The speed at which they work may best be gauged by considering that their daily output, on an average, is over 350 running yards per day, of a carriageway 24 ft. 7 ins, wide, laid in two layers of a total thickness of 8-10 ins. On dead straight stretches as many as 580 yds. a day have been laid.
Tests Show the Saving.
The advantages of such motor roads for commercial transport should be obvious, but, perhaps, one duly authenticated result of a test with a lorry and trailer carrying well over 10 tons pay-load might serve to show the sped and economy which can be and is being realized. Over a distance of 100 miles, the fuel consumption was equal to 8.5 m.p.g. and the average speed 35.5 m.p.h. The accelerator and brake were used only Ave and three times respectively, whilst the clutch was operated only four times during this journey. The consequent saving in wear and tear on important working parts must thus be considerable and be an important factor in reducing repairs to a minimum. The absence of crossings, of oncoming traffic and of cyclists or pedestrians, combined with continuous good visibility, certainly reduces the strain of constant driving and the consequent nervous fatigue.
We can hope only that our own road authorities will soon realize how the terrible toll of road accidents might be reduced, how the motor industry might be benefited and how road transport might be speeded up to the advantage of the community, by the construction of a modern system of motor roads.