View Q&A

The Typical Section #16, shown below, shows High Tension Cable Barrier (HTCB) between the Ramp SW and the Bike Path/Shared Use Path. The questions I have are the following:

• Would the HTCB be the appropriate barrier to protect bicyclist/peds when it appears to be 15-20 feet from the HTCB to the Bike path, taking in consideration the slope rate of 6:1 or flatter the first 10 feet, and then 3:1 slope rate?


• If the Bike Path is located beyond the clear zone, would a barrier be still needed, or it doesn’t require protection?


• The district is considering the installation of chain link fence along the outside shoulder of the Bike Path on the side between the ramp pavement and path. Do you see any concerns with installing a 4’ high chain link fence at this location as long as the fence is outside the clear zone?

A few thoughts on the installation.

1. The appropriateness of the HTCB is somewhat dependent is on what system you are using and what its dynamic deflection would be. Currently, no HTCB has been tested adjacent to a 3:1 slope, so it is difficult to anticipate how the systems will react if the system deflection allows the vehicle to reach the 3:1 slope regardless of the bicycle path placement.
2. If the system deflection prevent interaction with the 3:1 slope, there would be little concern vehicle interaction with bike path.
3. Another consideration is that your install appears to be on the inside of a curve. This may increase the system deflections as the cables may not develop tension and lateral resistance as effectively. I don’t have any test data on cable deflection on the inside of curves, but the physics of the problem would suggest increased deflection. You would have to check with the manufacturer of the cable systems regarding their thoughts on curves and deflection.
4. If the bike barrier is outside the clear zone, but within the deflection range of the barrier, I believe it would still be an issue. In general, if the bike path is outside the clear zone, it would not require shielding. However, the risk and exposure of pedestrians on the bike path may warrant additional consideration due to the consequences of vehicle penetration into that area. That would really be a policy decision on Illinois part.
5. Installation of the fence outside the clear zone and bike path should be acceptable. Note that the fence may need to be bike/ped compliant depending on how close it is to the path.
6. One additional item to note is that the image below shows light poles between the barrier and the bike path. There would be concern with interaction of vehicles impacting the HTCB and then engaging the poles if the HTCB deflection allowed that interaction.

Thanks!