HIghway cap illustration

A highway cap, also known as a lid or cover, mitigates part of a depressed highway to a higher degree than just a bridge.

A highway cap is actually a very wide bridge, except that in addition to a street going over the bridge, many other things can be placed on top of the cap, such as parks, plazas, and small buildings. Caps typically range in length from a few hundred feet to a block or more. Caps hide much more of the highway from view than a bridge.

These structures require expensive maintenance and, occasionally, replacement. Highway caps are wider than bridges but shorter than tunnels. Typically, caps do not need special ventilation of exhaust pipe emissions, unlike tunnels. While caps can be an attractive alternative to standard bridges over a depressed highway, they only address the micro problems that the highway causes, not the macro issues. Moreover, highway caps hardwire the highway – making any future removal highly unlikely.

Community BenefitHighway-to-Boulevard ConversionLand Bridge
Reconnected CommunitiesEvery neighborhood is connectedOnly part of a project corridor is reconnected
Climate ActionNew clean transportation options will reduce greenhouse gas emissionsThe rebuilt highway will continue to produce greenhouse gas emissions
Traffic SafetyUniversal design features create safe and accessible streets for everyoneThe highway continues to cause severe injuries and death
Healthier Air QualityImproved air quality, less health impacts like asthma and cancer, and longer life expectanciesThe rebuilt highway continues to produce hazardous air and noise pollution, harming the health of those nearby
Cost EffectiveLow long-term costs because of reduced payment and bridgesExpensive to build and maintain
Economic JusticeHighway land is used for new housing, businesses, jobs and reparative investment along the entire corridorOpportunities for housing and business space are limited to the lid area
Affordable Transportation AccessZero-fare rapid transit, bikeways and walkable businesses increase access to daily needsTransportation options are not improved for households who can’t access or afford a car
People ServedServes more people along project corridorsServes a portion of one neighborhood

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