It was known as the Road of Life, Doroga zhizni: Дорога жизни, doroga zhizni. The Stavka ordered the building of the road even before Lake Ladoga froze, as it became clear that they were not able to lift the German blockade of the city. It was designated as a military vehicular road: voenno-avtomobil'naia doroga/BAD 101, and stretched between Kobona on the eastern shore, across Shlissel'burg Bay to Vaganova on the western shore. The German capture of Tikhvin on November 8th 1941 forced the Soviets to construct a much longer road, BAD 102, 17.5-20 miles long.
The road was built in extremely dificult conditios, under constant enemy fire; artillery and air bombardment. The builders also had to work around the changing conditions on the Lake itself, including cracks and fissures which often appeared in the ice, frequent storms and periodic thaws. The first cargo of supplies reached the besieged Leningrad on November 23rd.
Between the 18th and 28th November, engineers constructed a second route, 16.8 miles long from Kokkorevo via Kloch'ia Island to Kobona, and further routes to the north as the ice thickened (the winter of 1941/2 was unprecendentedly cold, with temperatures regularly reaching -40). By the end of December the ice was 3.2 feet deep, and covered in almost a foot of snow, and was able to sustain the weight of military vehicles up to the size of a KV Tank. By the end of all the road construction, they extended a total of 1106 miles, including road guides, communication points, medical and rescue points, feeding stations and combat seurity posts along the routes.
The intial success of the road in the 1941/2 winter was hampered by disorganisation and a temporary thaw in November before the onset of the very cold winter, but improved when party leaders Zhdanov and Kuznetsov took over operations. Daily shipments rose to 800 tons by December 23rd. This meant that the bread ration of Leningraders could be increased to 100 grams for workers/engineers and 75 grams for dependants/children (remmbering that 75 grams is one slice of bread). Still, the food shortages in the city were catastrophic, and the ice road increased it's supplies to up to 3 convoys a day. By the end of January 1943, food supplies were able to reach targets, but by this time most of the total 1.2 million casualities of the siege had died, mainly from starvation. But the drivers across the lake tried to achieve the target of "two convoys per driver per day", and successfully acheived by 261 drivers in january 1942, rising to 627 in March.
The Road of Life was also used to evacuate the sick, women, children and the elderly from the city, (11,296 in January; 117,434 in February; 221,947 in March and 163,392 in April) as well as munitions and industrial equipment from Leningrad's factories.
The thaw started towards the end of March, and all movement across the ice was halted on April 12th, when transport by boat and barge was used.
Thanks to David Glantz's "The Siege of Leningrad" for much of this information.