Daily Archives: October 25, 2013

When Do Pedestrian Grade Separations Make Sense?

Metro just approved a budget increase for the proposed pedestrian bridge across Lankershim and Universal Hollywood Drive at the Universal City Red Line station, bringing the total to $27.3 million (including $1.4 million diverted from Rail Preventative Maintenance – nice touch). Now to be fair, a lot of the cost of the pedestrian bridge is going to be in the three elevators. This is machinery that has to (a) cycle reliably hundreds of times every day, (b) hold up under exposure to the weather and the, um, indiscretions of the public, and (c) incorporate transparent materials so that it doesn’t attract crime.

But that’s not really the point. The bridge, or an equivalent tunnel, is a questionable expenditure because many people aren’t going to want to use it anyway. I’ll outsource that argument to Damien Newton over at Streetsblog, and move on to the general question of when pedestrian grade separations make sense.

It’s All About Destinations

Fundamentally, a pedestrian grade separation makes sense if it connects to strong destinations on both sides at the same elevation as the grade separation.

When I lived in Boston, I explained this using a simple comparison of three pedestrian grade separations in the city. The first is the bridge between the Prudential Center and Copley Place, crossing Huntington Av:

Everybody in Boston knows this bridge. On the left is the Prudential Center mall, office towers, and residences. On the right is the Copley Place mall and hotels. The main levels of these malls are at the same elevation as the pedestrian bridge, so if you’re crossing, the bridge is actually more convenient than going down to street level and back up. Note, though, that this doesn’t alleviate the need for crosswalks at street level, because it’s still unreasonable to expect people on the street to go up, over, and down to cross, so there are still crosswalks on Huntington.

The second is the underpass from Back Bay Station on the Orange Line to Copley Place, going under Dartmouth St. Most people know this underpass and have used it. It’s at the same elevation as the Back Bay Station subway platform, so it’s useful to connect to that. On the Copley Place side, there’s nothing that low; everything is at least one floor up. If you’re just crossing Dartmouth St, or going from Copley Place to the commuter rail, you’re not going to use this underpass.

The last location is the underpass at Mass Av Station on the Orange Line. Many people, even those who live or work in the area, don’t even know this underpass exists. On the south side, it connects to the subway mezzanine. On the north side, it connects to nothing; you have to go up to the street. The result is that no one uses this grade separation. As a result, at both Dartmouth St and Mass Av, the city ended up going back 20 years later and putting in crosswalks at the street level anyway.

Mass Av:

Dartmouth St:

Crosswalks Make Sense, Even at High Traffic Locations

If you want a comparison to Lankershim, Universal Hollywood Drive, and Campo de Cahuenga, you could take the case of the Leverett Circle pedestrian bridge in Boston. This bridge connected the sidewalks on opposite sides of O’Brien Highway and Storrow Drive, and the mezzanine of the elevated Science Park Green Line Station. These are high volume roadways (Storrow is almost a freeway), and there are ramps to the 93 freeway at this intersection – not unlike the heavy traffic on Lankershim and Campo de Cahuenga, and the ramps to the 101.

During construction for the Big Dig, parts of the bridge had to be demolished and replaced with temporary structures, and some pedestrian movements were provided with crosswalks. The plan was that when construction was complete, the pedestrian bridge would be rebuilt and the crosswalks eliminated. However, walking advocates in the city gained strength, and the Big Dig went ruinously and comically over budget. The reconstruction of the bridge was therefore cut from the project – it was a pedestrian facility that walking advocates didn’t want, and the project couldn’t afford to build.

Today, all legs of the intersection have crosswalks, and it’s a much more pleasant environment without the overhead bridges. This area gets a ton of pedestrian traffic, since it’s part of the recreation paths along the Charles River.

Back to Universal

With these lessons in mind, it’s pretty easy to see that Damien Newton is spot-on about the Universal City pedestrian bridge. No one is going to want to go up, over, and down. A tunnel would be a little better, because at least it would attract people going to or from the subway station, but it wouldn’t obviate the need for crosswalks on all legs of the intersection. Maybe I’m being overly optimistic about the rationality of the players involved, but hopefully the city can sit down with NBC Universal, explain these things, and figure out a better way to spend money on improvements here.

Downtown LA Skyways

We can also see the same factors in play in downtown LA, with the pedestrian bridges built along with all the “new downtown” skyscrapers like the Bonaventure. Since many of the buildings have active uses on the same levels as the bridges, they do see a reasonable amount of use, but they obviously don’t eliminate the need for crosswalks at street level. They’re also pretty cool for filming Batman scenes, so they have that going for them.

Downtown LA Pedestrian Tunnels?

One place I do think we have some potential for pedestrian grade separations is for pedestrian tunnels in downtown LA. For example, the owners of Macy’s Plaza recently announced their intent to connect the underground mall in their building directly to the 7th/Flower subway station. This is a new concept for LA, but it’s common in places like Seoul, where developers seem to really understand the value in having a direct connection from a busy subway station to their retail areas.

At 7th/Flower, I can think of two additional potential connections that might make sense.

The first is a no brainer. There’s a big hole in the ground right now at 7th and Figueroa, literally right across the street from the Figueroa entrance to 7th/Flower station. I’m not sure exactly what Korean Air has in mind for their subterranean levels, but if you’re building a 70-story building, the cost to build a hallway underneath Figueroa to connect to the subway station isn’t that bad. If they’re considering street level or underground retail, this would add value to their project.

The second is a little tougher, and might require cooperation among public agencies and several different private owners. Thomas Properties, which owns the block bounded by 5th, Flower, 6th, and Figueroa, is currently sitting on some vacant space in their underground mall. This retail center might benefit from a direct connection to 7th/Flower too. (Earlier concepts for the Regional Connector had a station right at the mall at 5th and Flower, but that’s just way too close to 7th/Flower and 2nd/Hope.)

Getting to that property would be considerably more difficult. The existing Blue Line tunnel, to be extended by the Regional Connector, ends just south of 6th. Building a separate walkway would probably be cheaper than rebuilding and widening the Blue Line tunnel here. Going under the sidewalk would mean interfering with a lot of utilities and foundation tiebacks.


Maybe – and it’s a big maybe – you could do something by redeveloping the two-story building on the NW corner of 7th and Flower, and providing an integral headhouse that would connect to the existing Flower St mezzanine level. From there north to 5th, you’d go through the basements of the existing buildings, which could be redeveloped. A concept like this would depend enormously on the types of foundations, relative elevations of basement levels, location of underground parking ramps and building machinery, and so on, not to mention the willingness of different private property owners to cooperate with each other. But it’s an intriguing concept to have in the back of your head, anyway.

Back to Universal Part II

Idle speculation about downtown aside, I just don’t see the point of a bridge at Lankershim. Prohibiting people from crossing the street at-grade, as was suggested at the Metro board meeting, is even worse. In general, people are going to walk where they need to walk – they’re not going to make huge detours like going over ped bridges or taking three crosswalks because you avoided putting one in so that you could gap out a signal phase a few seconds earlier. Design that doesn’t address the city the way people actually use it is bound to result in unpleasant streets and dangerous conditions.