Another common pairing are portable toilets on trailers known commonly as a "toilet trailer". These trailers are typically found in 1–2 toilet configurations with a hand wash ability using either a hand washing station or a plastic barrel full of water. These trailers are often seen on agricultural fields or at road construction sites. These restrooms are ideal for situations where the workers (users) are very mobile. However, this configuration has proven problematic; most modern portable toilet waste tank designs have proven inadequate to deal with the common problem of splash-outs from the waste holding tank while being towed down bumpy roads. Also, when being towed, the high winds blow in from the vents, creating a hurricane effect inside and ejecting any toilet paper rolls from the portable toilet if not secured.