In 1840 George Stephenson had reached the age of sixty, and desirous of rest and retirement, declared his intention of retiring from his profession. Shortly afterwards he resigned the charge of the principal railways of which he was chief engineer. One of these was the Manchester and Leeds Railway, and to this railway Mr Hawkshaw was appointed chief engineer 1n succession to Stephenson. It is curious that when engaged as assistant to Mr Nimmo he had helped to elaborate the plans and surveys of this very line. The first bill laid before Parliament, in 1831, was defeated by a combination of the land owners and the canal companies and it was not until 1836, and under the auspices of George Stephenson, that an Act was obtained authorising the construction of the line in a new form, and with the necessary modification of the original designs. This Act was amended and the first ground broken in the succeeding year.

When Mr Hawkshaw became engineer, the works had been partly carried out. The difficult nature of the district through which some of the branches of the Manchester and Leeds main line had to pass rendered it necessary to adopt steeper gradients than had hitherto been deemed suitable to be worked by locomotive engines and Mr Hawkshaw proved not only the practicability of such steeper gradients, but also their desirability, even when by taking a more circuitous route easier inclines could be secured. To these ideas there was strong opposition, and to maintain them he had a harder battle to fight than even that of the gauges; for opposed to him were not only some of the leading engineers of the day, but also the great authority of George Stephenson himself. As early as 1810 from experiments made at Killingworth Colliery, and apparently confirmed by later trials, Stephenson had been led to affirm that locomotives work at only half their power where a rising gradient of 1 in 260 has to be overcome, and that when the gradient is as high as 1 in 100, not less than three fourths of the propelling power is sacrificed.

Consequently it was with him a favourite axiom that, the power of the locomotive being limited, the utmost level of line ought to be secured at almost any cost, as being in the end the cheapest because tending to the least waste of power. Stephenson's engineering was accordingly directed to perforating the barriers of hills by tunnels, and securing levels. He was, however, as Mr Hawkshaw proved, on this point in error, and the conclusions at which the younger engineer arrived, disputed at first with some violence, came gradually to be assented to. Their recognition has conduced in not an inconsiderable degree to the extension of the railway system.

On the incorporation of the Manchester and Leeds Railway with the great network of the Lancashire and Yorkshire Company, under an Act passed in 1847, Mr. Hawkshaw was appointed engineer of this group of railways. As such he designed and executed all the new lines and branches made to complete this system, which is now one of the most important of the kingdom. As he is still consulting-engineer to the Lancashire and Yorkshire Railway Company putting out of view the time he spent in South America — he has been for a period of forty-five years concerned in the construction of the Lancashire and Yorkshire group of lines.

In addition to these undertakings, the building of various other railways in different parts of the country were superintended by Mr. Hawkshaw. Chief among these, from the magnitude of the works and as one of the most costly lines ever constructed in proportion to its length, was the extension of the South-Eastern Railway from London Bridge station to Charing Cross, with a branch to Cannon-street. This great work included the erection of two broad railway bridges over the Thames and two terminal stations with roofs of noble span and elevation. In Russia Mr. Hawkshaw constructed the Riga and Dunaburg and the Dunaburg and Witepsk lines.

He has, besides, reported on other lines in that country. The Mauritius Government railways were completed under his direction ; and among other duties of a kindred character he acts as consulting-engineer to the Madras and to the Eastern Bengal railways. In recent years he has devoted great part of his time to the construction of docks, harbours, and other water works. Among these we may name the Penarth dock and harbour near Cardiff, the Albert and other docks at Hull, the new South Dock of the East and West India Dock Companies System , the dock at Fleetwood, not however yet completed, and the Holyhead Breakwater. To this latter work Mr. Hawkshaw was appointed engineer by the Government in 1856, on the death of Mr. James Meadows Rendel, under whose superintendence the work was begun.