Dutch scientists show: the 1962 Alcatraz Escape was possible

14 December 2014 by Roy Meijer

On 11 June 1962, three prisoners escaped from the heavily guarded prison island of Alcatraz just north of San Francisco. Where did their handcrafted rubber boat take them that night? The fate of Clarence Anglin, John Anglin and Frank Morris has continued to mystify the world down to the present day. When Dutch scientists were developing a model of the San Francisco Bay to study the impact of sea-level rise, they realised that this model could also shed light on one of the USA’s most intriguing stories. They have now completed their simulation work and conclude that an escape was indeed possible. In hindsight, the best time to launch a boat from Alcatraz was 23.30, one and a half hours later than has generally been assumed. A rubber boat leaving Alcatraz at 23.30 would most likely have landed just north of the Golden Gate Bridge. The model also shows that debris in that scenario would be likely to wash up at Angel Island, exactly where one of the paddles and some personal belongings were found.

Flood risk

Nobody was thinking about Alcatraz when this study began. Olivier Hoes, a researcher at Delft University of Technology (TU Delft) and a consultant with Nelen & Schuurmans, was actually working on analysing the flood risk for large industrial facilities in San Francisco Bay at UC Berkeley. For that purpose, he modelled the bay area in considerable detail using 3Di, state-of-the-art hydraulic software. When he showed the results to his colleague Rolf Hut, a researcher at TU Delft, Rolf realised that the hydraulic model could be used to shed new light at the Great Escape from Alcatraz. “To my surprise, that had never been done before, except in a famous episode of MythBusters. The only extra data we needed was the tide information for that night, which was quickly found.”

50 ‘boats’

Rolf and Olivier turned to Fedor Baart, a hydraulic engineer at Deltares who is an expert on particle tracking. “We didn’t know exactly when the inmates launched their boats, or their precise starting point, and so we decided to release 50 ‘boats’ every 30 minutes between 20.00 and 04.00 from a range of possible escape spots at Alcatraz to see where they would end up. We added a paddling effect to the ‘boats’, as we assumed the prisoners would paddle as they got closer to land”, Baart explains.

The is the scenario  in which the escapees do not peddle at all:

The scenario in which the escapees pedel to the north at a speed of 25 cm per second:

”The simulations show that if the prisoners had left before 23.00, they would have had absolutely no chance of surviving. The strong currents would have taken them out to sea. However, if they left between 23.00 and midnight, there is a good chance they reached Horseshoe Bay north of the Golden Gate Bridge”, Baart explains. The model predicts that any debris would then float back into the bay in the direction of Angel Island, exactly where the FBI found a paddle and some personal belongings.

“Of course, this doesn’t prove this was what really happened, but the latest and best hydraulic modelling information indicates that it was certainly possible. We also suspect the prisoners may have left later than has always been assumed because an escape at 22.00 doesn’t fit in with where the paddle was found. And, of course, it is really intriguing that the famous TV show MythBusters also found that the most likely landing place was Horseshoe Bay”, concludes Rolf Hut.

Hydraulic software

The researchers used the latest experimental simulation software to model the San Francisco Bay 3Di simulates flooding in two dimensions using a DEM. The 3Di package applies the finite-volume staggered grid method to shallow water equations with rapidly varying flows. The model runs in the cloud and can be used interactively during calculations. This allows decision-makers to assess flood consequences and risks ‘at the touch table’. 3Di was developed jointly by Deltares, Nelen & Schuurmans and TU Delft.
The model of the Alcatraz Escape will be presented at the AGU Fall Meeting on Tuesday, 16 December by, Fedor Baart (Deltares), Olivier Hoes (Nelen & Schuurmans and TU Delft), Rolf Hut (TU Delft) and Gennadii Donchyts (Deltares). The AGU is the world's largest conference in the field of earth sciences. It is attended by more than 24,000 scientists, policymakers, teachers and students, who meet to share pioneering research.

Fron left to right: Olivier Hoes, Fedor Baart en Rolf Hut (photo Mac Hamer, NOS)

More information

A lot of extra information can be found on the website of 3Di, including a video explaining the techniques used.

The BBC on this topic. 
See also NOS and Volkskrant (only in Dutch). 

Rolf Hut, this week in San Francisco r.w.hut@remove-this.tudelft.nl or Twitter @RolfHut

Science Information Officer TU Delft Roy Meijer, r.e.t.meijer@remove-this.tudelft.nl, +31 15 2781751

Carmen Boersma, spokesperson Deltares, Carmen.boersma@remove-this.deltares.nl, +31 88 3358101

© 2017 TU Delft