Highway Bridges.
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Specially written for "The Commercial Motor" by H. Howard Humphreys, M.Inst.C.E., M.Inst.Mech.E., Consulting Engineer on Roads to the British War Office.
Then comes the following important remark :—" As regards the bridges vested in the local authorities, we consider that they are adequately protected by section I, subsection (a), of the Locomotives on Highways Act, 1896, which enables the council of any county or county borough to make bye-laws preventing or restricting the use of motorcars upon any bridge within their area, where the council are satisfied that such use would be attended with damage to the bridge or danger to the public. We see no reason why protection might not also be given to private bridges through an application to the council to make bye-laws under this section." It will be noted that the Committee did not recommend any appeal clause in the event of councils' making bye-laws, and, judging from the experience gained under the !Leavy Locomotives Act, this omission is a very serious ene, for it is probably no exaggeration to say that, had an appeal not existed with regard to traction engines, they would by now have been numbered with other things of the past. As it is, the Local Government Board have handled the whole question of bye-laws made pursuant to the 1898
Locomotives Act with the utmost impartiality, and the result is that although the traffic is carried on under considerable and at times embarrassing restrictions, it is still possible.
Urgent Necessity for Amendment of Bridge Clauses in the Motor Car Acts.
It is clear that too much insistence cannot be placed upon the necessity for appeal, and it would seem advisable that, in ail cases, the appeal should be made to Me Local Government Board—rather than to the Board of Trade in some instances, and the Local Government Board in others, as is provided for by the r89S Locomotives Act. The latter body is thoroughly in touch with the whole of the highway and bridge question.
Whilst the laws respecting bridges are, upon the whole, more favourable to users of the heavy type of engine, there are certain weaknesses which should be corrected; for instance, a local authority may allow a bridge to fall into disrepair, and may then schedule the same on the ground that it is not strong enough to carry traffic which could have passed over it in safety when it was first built. The Local Government Board may use their influence (and have done so) with local authorities, in order to induce them to keep their bridges up to a proper standard of strength, but they cannot order the %rode to be done. It may be argued that the local council can be indicted, but the machinery for tieing this is so cumbrous and expensive that it is quite impossible to hope for any good from this method of procedure. The Hartley WintneyCouncil made a representation to the Board of Trade some years ago with reference to the defective condition of a large number et bridges on the London and Hampshire Canal : these were, and still are, in a very defective state. One of the Board's inspectors was sent down to report, and he recommended that steps should be taken to have them put right. Whether or not anything was done at the time, it is most certainly the fact that inany of the structures are in a deplorable condition to-day. In giving evidence before the Departmental Committee on Motorcars, Mr. Thomas, the manager of the Grand Junction Canal Company, stated that his company owned between three and four hundred bridges, and that, in spite of the fact that some of them N% ere not incapable of carrying heavy traffic, prohibitionary notices were to be placed upon all of them, thus rendering the owner of any heavy locomotive liable to be restrained by injunction from crossing. He further notified that his company might take action under the 1896 Locomotives Act as well.
It is interesting in this connection to note that the Leicester County Council, being inconvenienced about two of the bridges in question, took action recently ; the Local Government Board compelled the canal company to withdraw their notices, as the latter body were unable to prove in fact the weakness of the structures. Supposing that the eompany had been able actually to prove the structural weakness of this large number of bridges, the result would have been that a tract of country-, something like 125 miles in length, would have been absolutely severed, and any locomotive proprietor would have been required to make an enormous detour in order to cross a private profit-earning undertaking which had intersected public highways ! It is nume than likely that further action will be taken against the Grand Junction Canal Company in this matter, but it is a very great hardship that a concern which was made solely for the purpose of personal gain is in a position to inconvenience the public using the highways of this country. The manager of the canal company was extremely anxious to convince the Departmental Committee on Motorcars that the law wanted streagthening in the interests of his own and similar undertakings. Fortunately, however, he does not appear to have quite carried the Committee with him their recommendations, although not completely satisfactory, will not help private owners at the expense of the public to any great extent. "S""*".•
Structural Anomalies of Bridges.
Many anomalous structural conditions have been revealed by detailed inspections of a very large number of highway bridges. It has been by no means unusual, for instance, to find that a steel bridge has its main girders of maple cross-sectional strength for carrying heavy traffic, whilst its cross girders have proved to be quite inadequate to bear concentrated rolling loads. Such conditions show that bridges have probably been designed by draughtsmen who, in order to save trouble, have based their calculations upon loads per square foot (dead) rather than upon rolling loads combined with dead weight, and some few cases have occurred where the reverse condition as to girders has been shown. Another source of trouble is to be found in the fact that, after bridges are built, road metalling is from year to year thickened upon them, and eventually a structure that could have carried any weight allowed by Act of Parliament is barely sufficient to support itself, It must be remembered that the addiiion of 6in. of road metal, on a bridge 4oft. wide between the main girders, means an extra load of rather more
than i ton per foot run of roadway. It is not uncommon for councils to schedule short-span bridges against locomotives whilst they, at the same time, ask that their own steam rollers, weighing to, 12, or 15 tons, may be allowed to pass over them. Arguments have been heard at Local Government Board enquiries, in such eases, which, if seriously put forward, would appear to suggest that a road locomotive carries its trucks piled up and astride the boiler.
There are numerous cases where bridges have been widened in recent years, and where the widened portion is amply strong enough for any traffic, but no efforts appear to have been put forth to strengthen the older parts of the bridges, and to bring the whole up to an uniform standard of strength. It is believed that the Lwal Government Board, after the evidence which has been before them al enquiries held during the last few years, will refuse to grant loans for new bridges unless the structures arc designed with a sufficient margin of strength to allow for self-propelled traffic. It is not unreasonable to suggest, in the case of loans for widening, that the Board shall also insist upon the strengthening of the cld and weaker side at the same time that the addition is being made_ In brick bridges again, one of the most constant causes of failure is to be found in the weakness of the spandril wails; these are often forced outwards, partly because they were originally built too thin to act as retaining walls, and partly because they are not bonded in any way to the arches, and, where built in mortar of the ordinary type, water has got down at the back of them and gradually worked through the joints to the face, thus carrying away the essential portions of the mortar. The actual weight-carrying parts of these bridges, namely the arches, are strong enough under ordinary circumstances to bear almost any load. Other bridges fail because the percolation of water has been allowed to go on year after year and to carry away the bulk of the lime in solution —frost playing increasing havoc with the weakened mortar. A statement was made in one county that many of its bridges had remained unrepaired for too years.
it is fair, however, to give credit where credit is due, and the photographs .produced of Chetwynd Bridge and High Bridge, fIamisacre, in the first section of this article, show that, at any rate, tin Staffordshire County Council are prepared to do what is possible to meet the requirements of the public, as they have, at great expense, re-floored both of these fine struetures. The Northumberland .County C01111cil have taken like steps to strengthen
-elle of their bridges and roads, and the Lincoinshire Council (Kesteven), when making a schedule of prohibited bridges some years ago, limited the operations of the bye-laws to three years, in order to give the responsible local authorities a chance of rebuilding or repairing the same. Worcestershire, some thEM since, whea applicaticit It) close a great number of private bridges was made by the Great Western and Midland Railways, held a preliminary inquiry (conducted by various members of their own council) and, after hearing the evidence adduced by both sides, refused point blank to meet the wishes of the railway companies, holding, in effect, as the County of Buckinghamshire had done some years previously, that when a private company cuts through a public highway the bridges should be as strong as the road is upon either side.
• Another cause for considerable complaint on the part of the owners of self-propelled vehicles is due to the fact that private cornpanics, who rebuild their old structures, cannot be compelled to increase the strength to meet modern requirements. A wellknown instance of this occurred at a place near Ware, in Hertfordshire, some time since. It was known that locomotives were constantly using the highway, and yet a bridge was put in by the New River Company on one of the main roads—and with the full cognisance of the local authority—which would only just stand to tons. A contractor who was steam rolling for the council on the sante main road had an injunction granted against him, at the instance of the New River Company, for taking his steam roller over some of its structures.
Duke a considerable number of bridges may be known under the generic name of " tactical " structures, but these are generally located in such positions that they carry an important highway before it spreads out into a number of roads of lesser importance. The diseases which this class of bridge is said to suffer from are so numerous that it is impossible to attempt to enumerate them in detail. A preliminary CA: arte examination, and a final inspection by the Local Government Board, has often ended in a diagnosis which has differed so much from that supplied by the local authority that the bridges have been finally omitted from the bye-laws, and left to bear their burden in silence as before. Illuminating examples could be supplied by the score, but the value of a right of appeal is nowhere more forcibly rendered apparent than in instances of this nature. "The Range of Practical Politics." Photo ibtil
The Dcpar Miental Committee upon Highway Authorities and Administration, which reported in 1903, suggested that the Highways and Bridges Act of it should be amended so that the council at any administrative county might agree to take over private bridges (over which the public have a right of way) in the same manner that those councils may (by a section of the above-named Act) assume responsibility under certain conditions for the bridges of other highway authorities. It. is questioaable whether this is quite sufficient, at the present time, especially where county councils are composed largely of farmers, whose capacity for denouncing the badness of the present thee is only equalled by their power of resistance to any improved means and methods of transport which might probably have the effect of removing a large part of the grievances which they appear to cherish so highly. Is it within the bounds of possibility that councils so constituted will be likely to add to their responsibilities, more particularly as they now persist in looking at self-propelied traffic as being of use to one section of the community only, instead of a powerful national means of combating the pressure of external competition? There would have been comparatively little to complain about if the Departmental Committee had recommended (1) That county councils should have power to compel ownc-rs of private bridges to bring their structures up to the same strength that they were when originally built, or, alternatively, in the failure of the owners' doing this, the council to do the work themselves and to recover the cost in a court of summary jurisdiction (in the same way that certain sanitary works can be done); and (2) if, after being brought to the above state of repair, it were thought expedient, the county or local councils should assume the responsibility of maintenance,
There are certain advocates of an amendment of the law which would compel railway and other companies to strengthen their bridges, pari passtr, with increasing traffic. This is a gospel of perfection, which would not be acceptable at the moment to any Parliament. It should be possible for an inquiry to be held on the representation of any who inay be aggrieved by the laches of a local authority in the matter of bridge maintenance. The Board should have the power to order the authority to repair the bridgs if ladies are established. Extremists argue that every bridge in the country should be capable of carrying any weight, but this hardly seems equitable. The probability is that the matter will work itself out in a satisfactory way in a very short time, because the commercial motor will shortly be a tremendous factor in our national life, and the pressure of public opinion, added to the self-interest of councils who are, and will increasingly he, users of this form of haulage, will solve the difficulty so far as public bridges are concerned. In the case of new ventures, such as the construction of railways or canals, the question of the strength of " over bridges " should be as much a matter of attention by the Government authorities as is the strength of the structures carrying trains. Definite rides should be laid down by the Board of Trade, having due regard to the heaviest loading which is allowed by Act of Parliament, with a margin for future development in self-propelled vehicles. It would seem as though, at present, local authorities are left to fight the battle as to the strength of new " over bridges " themselves, and it not infrequently happens that railway bridges are reported upon by men whose knowledge of bridge construction is practically nil, This is hard upon the men themselves, for if they are conscientious in their work the. question must cause them much anxiety : but it is harder still upon the travelling public. If, on the other hand, the strengths of all new bridges were submitted to properly trained Government experts, the future at least would be catered for. If reference be made to the report of the Select Committee on Traction Engines on Roads, dated July tst, 1896, it will be found that the recommendation made is " In the case of new bridges, or those which may hereafter be re-built (at any rate on main roads), they
should, we think, be constructed to bear traction engine traffic." This recommendation is good so far as it goes, but, whilst the Local Government Board, in the case of rebuilding of public bridges, can, if they see fit, bring pressure upon a local authority by withholding sanction for a loan if the proposed bridge is improperly designed, the same power does not exist with regard to private undertakings.
A real difficulty has been discovered, recently, by the working of the 1898 Locomotives Act; no power seems to be given to local authorities to close " culverts "; but the question at once arises -What is a culvert? Is one to accept the negative definition that " a culvert is a structure which is built over water not flowing in a channel "? If so, it would almost appear as though a sin. pipe carrying water from a well-defined ditch on one side of the road to an equally well-delined. ditch on the other must of necessity be a " bridge "1 Whilst such an interpretation may be satisfactory to the legal mind, it hardly appeals to the layman. The whole question has been argued at length and with eloquence (and doubtless with profit also) by counsel, particularly in the cases of" Rex versus Oxfordshire " and " Rex versus Derbyshire." In the former case, Chislehampton bridge, which spans the Thame, was approached by a long causeway pierced with arches for the conveyance of flood water; these arches were necessary for the safety of the bridge, but were held not to be repairable by the county, although it does not seem very clear as to whether the reason for the exemption was that the arches were in fact culverts, or whether it was because they were situated at a distance of 300ft. from the end of the bridge (vide Highways Act 1835). The tendency with certain local authorities is to group culverts and bridges together, and the 1-,`arnharn Rural District Council have recently distinguished themselves by issuing a prohibitory notice to users of selfpropelled traffic. The legality of this notice will probably be tested. It would seem desirable to make some commonsense definition of the word "culvert," for the Legislature, surely, never intended the nation's highways should he blocked as the outcome of a parsimonious failure to keep small and inexpensive structures in repair In determining what should be called a culvert, two factors should be considered, namely, (a) the span and (b) the height from the bed of the stream to the top of the arch, A reasonable span in this behalf would seem to be 6ft. and, so long as the height as before defined does not exceed twice the span, it may fairly be urged that the structure is a culvert in point of fact. Roads and bridges imperatively call for more attention, and more expense will be involved in maintenance; but there is such a thing as a wise extravagance. Is there one authority in the country that has quietly, impartially, and seriously, considered the advantage of investing money in new highways and bridges, instead of trenching on private enterprise?