The company established primacy in some areas, but remained less than successful in others; considerable sums were expended in the process, not always finding the approval of shareholders.

It extended from Aberdeen to Portpatrick, and from Oban to Carlisle, running express passenger services and a heavy mineral traffic.

These two lines worked in harmony, merging to form the Glasgow, Garnkirk and Coatbridge Railway in 1841, and competing with the M&KR and its allies.

A major difficulty was the terrain of the Southern Uplands: a route running through the hilly lands would involve steep and lengthy gradients that were challenging for the engine power of the time; a route around them, either to the west or the east, involved much lengthier main lines, and made connection to both Edinburgh and Glasgow more problematic.

[4] The Glasgow and Edinburgh lines combined at Carstairs in Clydesdale, and the route then crossed over Beattock Summit and continued on through Annandale.

[13] The promoters had engaged in a frenzy of provisional acquisitions of other lines being put forward or already being constructed, as they considered it was vital to secure territory to their own control and to exclude competing concerns as far as possible.

There were also suggestions of improper share acquisitions, and in the period 1848 to 1850 a number of shareholder inquiries disclosed bad practices, and many board members had to resign in February 1850.

As new coal mines opened, so new branches were needed, connecting Coalburn, Stonehouse, Strathaven, Muirkirk and Darvel and many other places, with new lines built right up until 1905.

It considerably shortened the route to the Lanarkshire ironworks, and was heavily used at first, but the traffic was depleted by cheap imported iron ore within a decade.

It extended from Townhead to Buchanan Street, an "inadequate and very cramped station"[22] in 1849, but the route from there to the southwards main line was very circuitous.

[23] Another scheme failed to get finance in 1866 and again in 1873, but the Caledonian Railway (Gordon Street Station Connecting Lines) Act 1875 (38 & 39 Vict.

c. cxxxiii) was obtained to build a bridge crossing the Clyde and bringing the South Side route into the city centre.

It was commissioned on 3 May 1908; it had 374 miniature levers, the largest of its type in the world, operating points and signals by electro-pneumatic and electro-magnetic equipment.

[14] With the intention of revitalising the lead mining industry, the Leadhills and Wanlockhead Branch was opened as a light railway from Elvanfoot in 1901–02.

With challenging gradients to reach Scotland's highest village in otherwise remote territory, the line scraped a bare living and closed in 1938.

[14] In the mid-1850s the steamer connections on the Firth of Clyde assumed ever increasing importance, and journey transit times from settlements in Argyll and the islands to Glasgow became critical.

[26] In competing with rival rail and steamer connections, the Caledonian became frustrated with its reliance on independent steamer operators, and tried to obtain powers to operate the vessels directly; this was refused by Parliament on competition grounds, and in reaction the company founded the nominally independent Caledonian Steam Packet Company in 1889.

[27] In the final decades of the 19th century, as the cities spread into conurbations, the company's attention turned to increasing traffic in areas now thought of as "suburban".

The North British Railway and its satellites had gained an early monopoly of this traffic, but its importance encouraged the Caledonian to enter the area.

In 1903–04 it was extended eastwards to Cathcart and Newton, enabling the heavy mineral trains to avoid the Joint Line and the congested area around Gushetfaulds from the Lanarkshire coalfields to Ardrossan Harbour.

[14][29] The Caledonian Railway entered Edinburgh from Carstairs on 15 February 1848; its terminus was a one-platform station named Lothian Road.

This was the first line to offer travel without change of carriage between Edinburgh and London: passengers on the rival North British Railway needed to cross the River Tweed on foot to continue their rail journey.

Both were unsuccessful adjuncts to the Dundee and Newtyle Railway, built using stone block sleepers and a track gauge of 4 ft 6+1⁄2 in (1,384 mm).

At the time of the absorption the SNER and the Great North of Scotland Railway were engaged in building a through line at Aberdeen, with a new Joint station; it opened in 1867.

This came at a cost: Parliament became increasingly uncomfortable with monopolies of this kind, and when the North British Railway protested, it was given running powers over much of the Caledonian's northern system.

Competition between the companies on the east and west coast routes from London to Aberdeen led in 1895 to what the press called the Race to the North.

The Forfar and Brechin Railway was promoted as a potential alternative main line; it opened in 1895 but remained simply a rural branch.

The Caledonian absorbed the SCR in 1865 and the directors were dismayed at the level of commitment to a difficult construction scheme barely started.

In 1893 the Crieff and Comrie Railway made a short extension into Strathearn, and this encouraged ideas of completing a link right through to the Callander and Oban line.

From September 1888 a further riband was added below the Nemo me impune lacessit motto; this bore the words Caledonian Railway Company.