Cross section of the San Francisco-Oakland Bay Bridge, 1947
The Modern Transit Society web site has moved.
To obtain this page in the latest version, change "trainweb.org/mts" to "moderntransit.org" in the URL (web address).
Below is an archived version (September 2005).
Cross section of the San Francisco-Oakland Bay Bridge, looking
eastward. It shows that at least as early as 1947, highway engineers
contemplated eliminating the trains (top drawing) and replacing them
with more automobile lanes (bottom drawing, showing options of either
10 lanes or 12 lanes for automobiles). This drawing was included in
the report "Preliminary Studies for an Additional Bridge Across San
Francisco Bay", California Dept. of Public Works, 3/31/47. In
contrast to the highway engineers' and GM's desires, the report
concludes "it is essential that the electric railways be retained on
the present bridge."
My measurements of the original of this drawing, measuring the
deck width to the accuracy possible using a fine ruler, shows that
the trains only took 19.88 % of the bridge
=5.51 cm/(12.95 cm * 2 decks). Common
practice is to round to the nearest whole feet, so this value is
either 20% =24 feet/60 feet /2 decks or
19.17% =23 feet/60 feet/2 decks. Since
19.88 is much closer to 20 than to 19.17, the conclusion is that the
trains took only 20% of the bridge.
