At the same time, the extensive investment of Union Pacific funds to secure gains unconnected with increase of traffic over its lines has provoked merited criticism. A railroad is, after all, a machine for transporting passengers and goods, not an engine of speculation; and both from the point of view of the community which it serves and of the investors who hold its securities it is advisable that its income should depend on the business which its managers conduct and are responsible for, and not on circumstances over which they have no control. So far as Union Pacific purchases have been designed to open connections or to modify competition they have had a sound foundation. So far as they have been financial operations only they are not to be commended.[540] From the point of view of operation the success of the Union Pacific has been remarkable. Like most roads it came out of its receivership in better shape than it went in, but with much lacking for the efficient and economical handling of its traffic. Since 1900 over $52,000,000 have been invested in betterments and in new equipment, of which some $15,000,000 have been withdrawn directly from income. Maintenance charges have also been liberal, particularly in the last few years. Grades and curves have been eliminated, steel bridges have been put in place of wooden, new and heavier rails have been laid, ballast supplied, and equipment greatly enlarged and improved. Whereas in 1896 13 per cent of all the Union Pacific system was laid with iron rails, and only 24 per cent had rails weighing more than sixty pounds to the yard, in 1907 there was no iron reported, and only 33 per cent of the track did _not_ have rails weighing more than sixty pounds to the yard. The average capacity of freight cars was a shade over twenty tons in February, 1898; it was over thirty-four tons on June 30, 1907, and the new freight cars added during the last-named year averaged a capacity of sixty-seven tons apiece. In consequence of these improvements the Union Pacific has been able to handle a very greatly increased business. Between 1899 and 1907 the tons of revenue freight carried one mile increased from 1,393,207,990 to 5,704,061,535, and the passengers carried one mile from 167,117,388 to 680,278,509. This fourfold increase has been packed away in the larger cars, which in turn have been combined into longer trains. Twenty-one tons are now put into the average freight car, and thirty-two freight cars form an average train. In 1899 the average car held twelve tons and twenty-nine of them carried a train-load. Sixty-six is the average number of passengers per train to-day; thirty-three was the average number in 1899. And so the increased business has not occasioned a proportionate growth in cost. It takes but little more than three times the outlay in conducting transportation to do over four times the work, and other railroad expenses have varied even less.