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Roadside ditches are an effective type of open drainage system that allows for runoff to be quickly collected out of the streets. Typically, applicable to streets with higher elevation that the surrounding properties, they provide drainage capacity, water quality and other benefits, along however with some challenges such as need for consistent maintenance to avoid obstructions (vegetation, litter, e.g.) but also proximity to vehicular traffic when present in narrow streets. Houston faces these challenges in certain neighborhoods and cases of vehicles driving into the ditches are increasingly seen at nighttime. Does any other locality/jurisdiction experience this issue? And if so, what traffic safety applications do you use? Houston would like to explore alternatives that are cost-effective and demand reasonable maintenance.
Are these incidents located only in specific areas? (at curves, for example)
It may be worth looking at something like adding curb and gutter with curb cuts to those street sections where incidents are occurring. Obviously hydraulic analysis would be needed to determine the size and frequency of the curb openings. They could be long stretches of no curb where safe or more frequent smaller openings.
Curb openings are often to bioswales, but they could also lead to a traditional ditch. The image below shows curb at the curves but a curb opening on part of the straightaway
Thanks Heidi. These ditches are not located in specific areas, just on narrow neighborhood streets where it is hard to accommodate for standard cross sections. When the local drainage system is rehabilitated, these ditches get to be re-established within the available ROW and in some scenarios room for buffer is not even feasible although depths are kept under 4-ft. See sample images.
------------------------------Johana Clark P.E., M.ASCESenior Assistant DirectorCity of HoustonHouston TX------------------------------
Yikes. Maybe someone else will have a recommendation based on their experience.
I'm not sure how to remedy that situation without adding storm sewer and inlets in-lieu of the steep ditch. Ideally, the ditches should be limited to around 4:1 (H:V) slope for vehicle safety.
------------------------------Johana Clark P.E., M.ASCESenior Assistant DirectorCity of HoustonHouston TXOriginal Message:Sent: 06-06-2023 09:44 AMFrom: Heidi WallaceSubject: Traffic Safety in Roadside Ditch Local Streets
The issue of vehicles driving into roadside ditches is not unique to Houston. Many localities and jurisdictions in the United States face similar challenges with open drainage systems. Typically areas with low-lying terrain, where drainage systems and roadside ditches are critical for managing stormwater runoff, commonly face similar challenges. For instance:In 2020, a man was seriously injured after his car drove into a roadside ditch in Portland. This led to the city installing bright lights in roadside ditches to make them more visible to drivers at night.In 2021, a pedestrian was killed in Chicago after she was struck by a car that had driven off the road and into a roadside ditch. This led to the city installing fencing around roadside ditches to protect pedestrians from being hit by cars.In 2022, a driver was killed after his car drove into a roadside ditch in Denver. This led to the city installing reflective markers on roadside ditches to make them more visible to drivers at night. Guardrails are generally the most expensive option, but they are also the most effective. Ditch lights and ditch fencing are less expensive, but they may not be as effective as guardrails.Some more creative solutions to consider are: Planting trees and shrubs around roadside ditches can help to create a visual barrier that discourages drivers from driving off the road. This is a cost-effective solution that can also improve the aesthetics of the area.Installing solar-powered lights on roadside ditches can help to make them more visible at night. Placing reflective markers and delineators along the edges of the ditches can enhance visibility, especially at night.Using raised pavement markers, also known as road studs or cat's eyes, can provide both visual and tactile feedback to drivers. The Ditch Art Project in Chicago project invited artists to create sculptures and murals in roadside ditches. The art has made the ditches more visually appealing and has also helped to raise awareness of the dangers of driving off the road.In addition to these solutions, there are a number of general traffic safety measures that can be taken to reduce the risk of vehicles driving into roadside ditches, including: enforcing speed limits, installing warning signs, improving road visibility and public education. Additional resources that might be useful to read: FHWA Maintenance of Drainage Features for Safety: https://safety.fhwa.dot.gov/local_rural/training/fhwasa09024/ Finally, As an active civil engineering firm in Houston for the past 10 years, we have encountered several design and enforcement issues that may contribute to the problem. One of these issues is the insufficient restoration practices when private developments are constructed along roadside ditches. Additionally, the lack of current enforcement regarding the safe design and implementation of roadside ditches by design firms or contractors is also a concern. Furthermore, the enforcement of city sidewalk ordinances has resulted in the need to allocate the ditch area to meet sidewalk requirements. It is worth noting that the city is now less inclined to permit the covering of ditches.