Patricia Cain has won this year's £25,000 Threadneedle Prize for pastel piece Building the Riverside Museum.
Selectors praised the "confident lines of colour" in her large-scale industrial drawing of the construction of Glasgow's new transport museum.
Duo Boyd and Evans won a further £10,000 prize voted for by visitors to the Threadneedle exhibition.
The two pieces and a further 44 entries are on display at London's Mall Galleries until Saturday.
More than 2,100 entries were submitted in total.
The work of Cain, who trained as a lawyer before becoming a full-time artist and completing a PhD at the Glasgow School of Art, focuses on the regeneration of the city.
"Cain uses pastel, often considered a difficult medium, to create large-scale industrial drawings where broad and confident lines of colour build a structure into the work that replicates its subject matter," organisers said.
Cain has said of her piece: "My role was to capture the experience of the moment of building work in progress.
"The focus is not the finished building but an investigation of the beauty of construction."
The Glasgow Riverside Museum of Transport was designed by architect Zaha Hadid.
Milton Keynes-based husband and wife team Fionnuala Boyd and Les Evans won the Visitors' Choice award for Clee Hill 2009, "depicting a barren landscape in Shropshire after heavy rain".
Boyd and Evans create paintings from photographs "where perspective and scale are heavily altered to produce surreal effects and to investigate ideas about representation".
The couple, who have worked together since 1968, have artwork in public collections at galleries including the Museum of Modern Art in New York.