As with the Eiffel Tower this project got very large, very quickly. The final bridge has towers about 6 feet tall and spans a total length of 15 feet. The height and width of the bridge are in proportion to one another and reflect a scale of roughly 1 stud == 1 meter. The length of the bridge is much shorter that real proportions (had the length been built in correct proportion, the center span would have exceeded 25 feet (!) -- much larger than time, budget, and physical space would allow).
Red was the obvious choice for the bridge. In The Ultimate LEGO Book it is mentioned that the LEGOLAND theme park in California has a bridge built of special 'international orange' colored bricks. Red was the closest I had, and it seemed appropriate enough to me (the LL park bridge is also a much larger scale).
The bridge actually uses very few bricks considering its overall length. The towers are quite narrow, and the spans fairly minimal. That is not to say I didn't need to bulk order a number of pieces, though. The bridge uses roughly 400 2x8 red plates, over 800 1x8 gray bricks for the roadways, and about 1500 1x6 red plates for the 'cables'.
Unlike the real bridge, this model is not a suspension bridge... I had to cheat with a couple of support columns under the middle of the central span (actually, I'm not POSITIVE these are needed (the strength of the span may hold itself up), but I'm not going to risk it before the exhibition).
The roadway sections have the correct number of lanes (six) and were constructed with grays bricks and gray and white plates and then laid on their side to achieve a smooth surface.
The biggest question I got from friends when starting the project was about the suspension cables. How would I build those? It would have been nice to somehow string together a few thousand 1x1 red cylinder pieces, but that wasn't really an option. What I hit upon was using bunches and bunches of 1x6 red plates connected at their endpoints. This created a 'chain' which could then be curved as needed, and more plates were then dropped vertically to attach it to the span below.
Finally, this project gave me a chance to use some of the multitude of tiny wheel pieces I have accumulated over the years (mainly from the seasonal Advent Calendar sets). They worked perfectly in miniature cars. Lauren and I sat around and built a couple dozen before this webpage was made, and I suspect I'll build many, many more during the next three weeks before the exhibit. The cars are so tiny that it is had to get very creative with them, so they all kind of look the same. But, I'd hate to have the bridge built and no cars on it...
For those interested in the statistics of the real Golden Gate Bridge...