Why is the bridge so low? 
 
 This train trestle is about 100 years old. At the time when it was built, there were no standards for minimum clearance.. 
 
 How often do trucks crash into the bridge? 
 
 On average, about once a month a truck gets visibly damaged at the bridge. However, every day I see trucks that trip the overheight warning lights, stop and turn into the side street. 
 
 Why don’t they fix it? 
 
 Depends on who “they” are and on what “fix” means. 
 
 The North Carolina Railroad Company owns the train trestle, and their concern is primarily with keeping the trains running and keeping them running safely. So their concern is mainly with reducing the impact of the truck crashes on the actual structure of the train trestle. As far as they are concerned, they solved that problem by installing the crash beam. 
 
 The city of Durham has installed “low clearance” signs on each of the 3 blocks leading up to the trestle (Gregson is a one-way road). There is a sensor that triggers an LED blackout warning sign when In overheight vehicle approaches the trestle (more info below). Several blocks ahead of the trestle the speed limit is 25 MPH. The folks from the city planning department said that they made an effort to prevent accidents. 
 
 The North Carolina Dept. of Transportation maintains the road, but not the signage. I suspect they have much bigger problems to deal with statewide than this bridge. 
 
 Is the clearance signage accurate? 
 
 The clearance signage displays a maximum safe clearance – and yes, in that sense it is accurate. The actual clearance of the crash beam right in front of the trestle is 11 feet 10.8 inches, which gives it a 2.8 inch safety margin. The MUTCD allows for a maximum of 3 inches difference between the signage and the actual clearance. 
 
 Metric, please! 
 
 Would this situation be better if the signage were metric? Well … take a look at his website: 2m40.com (Warning: French. Metric) 
 
 For the convenience of our metric-only audience, here are the measurements we’re talking about in Meters: 
 
 11foot8 (11 feet 8 inches) = 3.556 meters 
 
 11 feet 10.8 inches = 3.627 meters 
 
 Safety margin: 7.1 cm (at the crest of the road) 
 
 Can’t the road be lowered? 
 
 That would be prohibitively expensive because a sewer main runs just a few feet below the road bed. That sewer main also dates back about a hundred years and, again, at the time there were no real standards for minimum clearance for railroad underpasses. 
 
 Can’t the bridge be raised? 
 
 Here, too, the question is who would want to pay the millions of dollars to raise the tracks a couple of feet? To accomplish this, the grade of the tracks would have to changed on both sides of the trestle, probably for several miles. That would require rebuilding all trestles in Durham. And NS would have to shut down this busy track for months. I don’t think they are interested in that idea. 
 
 Is the signage adequate? 
 
 The signage is good, and the vast majority of truck drivers notice the problem and avoid the bridge. Large signs alert driver to the low clearance several blocks before the bridge. Half a block before the trestle, a sensor detects overheight vehicles and triggers an LED blackout warning sign that was installed in May 2016. That same sensor also triggers a red-light phase at the traffic light directly in front of the trestle (installed in March 2016), so the driver has 50 seconds to read the warning sign next to the red traffic light and consider their next move. 
 
 Should there be more signage? 
 
 It’s hard to see how more “low-clearance” signs will significantly improve the situation. 
 
 Could they install a low-clearance bar? 
 
 A low clearance bar is a bar suspended by chains ahead of the bridge. Overheight vehicles hit that bar first and the noise alerts the driver to to the problem. I understand that this approach has been successful in other places, but it’s not practical here. There are many overheight trucks that have to be able to drive right up to the bridge and turn onto Peabody St. in order to deliver supplies to several restaurants. Making Peabody St inaccessible from Gregson St would make the restaurant owners and the delivery drivers very unhappy. 
 
 Are the drivers stupid? 
 
 No idea. They certainly seem distracted and the rental truck drivers are also probably inexperienced. 
 
 Will insurance cover the damages? 
 
 Most truck rental insurance policies specifically exclude overhead damage from coverage. However, a good auto insurance or liability insurance might pick up the tab. Check with your agent. Or even better – don’t hit the bridge! 
 
 What is the location of the 11foot8 bridge? 
 
 201 Gregson St in Durham, NC (intersection with Peabody St) Link to Google maps 
 
 Any other questions? 
 
 If you have any truck-crash-related questions that are not covered here, post them below. ||||| Vertical Clearance 
 
 The adopted criteria provide vertical clearance values for the various highway functional classifications (Table 19). These criteria are set to provide at least a 1-foot differential between the maximum legal vehicle height and the roadway, with additional allowances for future resurfacing. These clearances apply to the entire roadway width (traveled way and shoulders). A formal design exception is required whenever these criteria are not met for the applicable functional classification. 
 
 Clarifications 
 
 The specific standards for vertical clearance adopted for the Interstate System maintain its integrity for national defense purposes. On Interstates, the clear height of structures shall not be less than 16 feet (4.9 meters) over the entire roadway width, including the useable width of shoulder. In urban areas, the 16-foot (4.9-meter) clearance shall apply to at least a single routing. On other urban Interstate routes, the clear height shall not be less than 14 feet (4.3 meters). A design exception is required if this standard is not met. Exceptions on the Interstate must also be coordinated with the Military Surface Deployment and Distribution Command Transportation Engineering Agency of the Department of Defense. 
 
 TABLE 19 Ranges for Minimum Vertical Clearance Type of Roadway Rural Urban US (feet) Metric (meters) US (feet) Metric (meters) Freeway 14–16* 4.3–4.9* 14–16* 4.3–4.9* Arterial 14–16 4.3–4.9 14–16 4.3–4.9 Collector 14 4.3 14 4.3 Local 14 4.3 14 4.3 
 
 *17 feet (5.1 meters) for sign trusses and pedestrian overpasses. 
 
 Source: A Policy on Geometric Design of Highways and Streets, AASHTO 
 
 Substantive Safety 
 
 The adverse effects of structures with insufficient vertical clearance are obvious (see FIGURE 24). Impacts to low bridges create risk for the driver of the vehicle, others on both roadways, and in extreme situations can result in closure of the bridge for lengthy periods and necessitating costly repairs. 
 
 FIGURE 24 Interstate closure after an impact with a bridge. 
 
 Figure 24 is a photo showing damage caused to the underside of an interstate bridge as a result of being struck by a vehicle that was too tall to pass underneath. Pieces of concrete are scattered over the roadway, completely closing that direction of the interstate. 
 
 Summary 
 
 Table 20 summarizes the potential adverse impacts to safety and operations of a design exception for vertical clearance. 
 
 TABLE 20 Vertical Clearance: Potential Adverse Impacts to Safety and Operations Safety & Operational Issues Freeway Expressway Rural 
 
 Two-Lane Urban Arterial Collision with overhead structure X X X X Rear-end crashes (vehicles following the vehicle that collided with the structure) X X X X Debris on the roadway X X X X Long delays as a result of a closed roadway or lanes X X X X 
 
 Freeway: high-speed, multi-lane divided highway with interchange access only (rural or urban). 
 
 Expressway: high-speed, multi-lane divided arterial with interchange and at-grade access (rural or urban). 
 
 Rural 2-Lane: high-speed, undivided rural highway (arterial, collector, or local). 
 
 Urban Arterial: urban arterials with speeds 45 mi/h (70 km/h) or less. 
 
 Vertical Clearance Resources 
 
 A Policy on Design Standards Interstate System , AASHTO, 2005. 
 
 
 
 
 
 , AASHTO, 2005. Federal Aid Policy Guide , FHWA, 2005. 
 
 
 
 
 
 , FHWA, 2005. A Policy on Geometric Design of Highways and Streets , AASHTO, 2004. 
 
 
 
 
 
 , AASHTO, 2004. Guidelines for Geometric Design of Very Low-Volume Local Roads (ADT ≤ 400) , AASHTO, 2001. 
 
 
 
 
 
 Back to the Table of Contents ||||| More than 100 vehicles have crashed into a low bridge in Durham, N.C., since 2008. Jürgen Henn tracks it all on his website, 11foot8.com. Photo: Jürgen Henn/11foot8.com 
 
 DURHAM, N.C.—A height sensor on the street detected impending doom here last month. Yellow lights began flashing a block away. The danger: A Budget rental truck barging down the road wasn’t going to get under the railroad overpass. 
 
 The truck ignored the warning. It rumbled underneath. Its roof did not. 
 
 The train bridge’s underside trimmed... ||||| The seed for Wide00014 was: 
 
 - Slash pages from every domain on the web: 
 
 
 
 
 
 -- a ranking of all URLs that have more than one incoming inter-domain link (rank was determined by number of incoming links using Wide00012 inter domain links) 
 
 
 
 -- up to a maximum of 100 most highly ranked URLs per domain 
 
 - Top ranked pages (up to a max of 100) from every linked-to domain using the Wide00012 inter-domain navigational link graph
– There are signs and warning lights that flash. But, still, box trucks, campers, and other tall vehicles keep taking on the notoriously low railroad bridge at Peabody and Gregson streets in Durham, NC. And they keep losing. The bridge has shaved the tops off of more than 100 vehicles since 2008, and Jürgen Henn has captured it all on video, the Wall Street Journal reports. "It can be pretty spectacular," he says. Henn works in a building near the bridge. After witnessing several accidents, he says, "I figured I’d keep track of it for a while." He aimed a security camera at the bridge. Then added a second camera on a building across the street, along with an infrared camera to capture nighttime wrecks. Some of his videos have more than a million views, per the Journal. You can buy "crash art" and T-shirts on his website. The bridge, which offers 11-feet-8-inches of clearance, was built about a century ago, according to Henn. During the intervening decades, the Journal notes, vehicles have gotten taller. Today, minimum vertical clearance for a bridge is 14 feet. Since 2008, there have been no fatalities due to the Durham bridge and just one minor injury, the state transportation department tells the Journal, but there has been a toll: more than $500,000 in vehicle damage. Each time the bridge is bashed—about once a month, Henn says—inspectors check it for damage, according to an earlier report by WRAL. To curb crashes, the city installed a height sensor that triggers flashing lights when a truck is too high to clear the span. Since the accidents keep happening, the city is now connecting that sensor with a traffic light in hopes drivers who are forced to stop will eventually figure out that their best bet is to turn before slamming into the bridge. (Another span making headlines? One inspired by da Vinci.)