The Montgomery advertiser., 1902-12-07

roadway of the main bridge. There are two ties to each pier and they consist of flat steel bars F inches by inch. In this way attachment is made between the opposite piers, which thus form cantilev- CTS At the shore ends the temporary bridges are supported by timber trestles built up from the stairs leading down to the river The spaces between the ends of the steel girders, where they rest on the cantiiever piles, are filled up with timber SO as to afford continuous run way for the cranes.
 The erection of the steel spans was task of some difficulty. as 1t was not per mitted to put false work in the river so as to obstruct the arches. The largest span weighed these had to be raised bodily 90 to 8 feet. and deposited on the piers. The contractors for the erection were Messrs ]. H. and W. Bell of Liv- erpoo a firm which devotes itself to work of this nature. The general con- tractors for the whole work. 1t should be stated are Messrs. Pethick Brothers of Plymouth. while the contractors for the steel work are the Patent Shaft and Axletree Company of Wednesbury. The steel girders were put together on a large
 floating pontoon moored near the bridge. This pontocn was l13 feet long. 50 feet wide. and feet deep. To assist in build lIR up lIe RiTutTS d tfdCh war iofN AtOAAs end to end in which a steam travelling crane ran The steel work was delivered on to the pontoon in sections of size convenient for transportation from We'd esbury, and the parts were bolted to- gether to form the spans. The pontoon was then placed athwart the arch against which the span had to be erected It was very neeessanD that the pontoon should be held securely and steadily in the right position for depositing the span. and some remarkable ground tackle had to be used for moorings. The pontoons being in position the operation of raising the lengths of lattice girder work was commenced. For this purpose two sets of legs. or gallows frames, were erected on the pontoon at a convenient distance apart. Each one consisted of two balks of pitch pne 4S feet long. and in cross section 20 inches by 20 inches square. These uprights were connected at the top by crosspiece to which the lifting tackle was attached. By means of steam winches on, the pontoon the span was raised and deposited in position on canti- lever piers. To remove the pontoon 1t was necessary to lower one of each pair of the timber balks, and this was made possible by pivoting them at the deck, much in the same way as the mast or sailing barge The transom pieces con- meeting the two balks had also to be up- ended.
 It will be seen that the work was of some magnitude to be carried out on floating platform moored traversely to the run of the tide, but the difficulty of the operations was increased by the limited time allowed. The actual lifting of the spans occupied between fifteen and twen- ty minutes; the time required for taking the pontoon from its original position and back again was about three hours. In this work two of the powerful "kais- er' tugs were employed. and good deal of skilful watermanship, in which the Thames men are not surpassed by those of any other river in the world. was dis- played. The time for fixing the ten spans was ffty-four days. the total weight dealt with being about 300 tons.
 The whole workis an instance of the i'm portance now attached to the continuity of traffic. If London Bridge could have been closed the work of widening would have been simple; but even if one foot path at the time had been appropriated, with perhaps a small part of the road way, the need for the two temporary bridges would have been obviated. Again, | had the Contractors been allowed to ob- \ struct the river. the need for speed Tn | the erection of the spans would not have arisen, and speed in such work means | expense. As it is, a novel piece Of en- | gineering work has been very creditably | carried out; and there will be no damming | of the ceaseless streams of traffic that pass over and under London Bridge.