Evaluation of the Efficiency of a Speed Monitoring Display (SMD) in a Very Short-Term Roadwork Zone

Roadwork zones are high-risk environments where sudden geometric changes, narrowed lanes, and driver unfamiliarity frequently lead to inappropriate speeds. Ensuring safe vehicle speeds in roadwork zones remains a priority due to drivers’ limited perception of risk and frequent non-compliance with temporary limits. This study evaluates the effectiveness of a speed monitoring display (SMD) installed in a nighttime, four-day motorway roadwork site involving a temporary median crossing, where traffic was diverted through a single lane and a chicane-type re-entry. Speed data were collected at two points, 100 and 50 m before the median crossing, labelled as P1 and P2, respectively, during two phases: with standard work zone signage only (Phase 1) and with an SMD added (Phase 2). Results show statistically significant reductions in mean speed after SMD installation at both measurement points, including decreases of 7.09 km/h at P1 and 4.69 km/h at P2, with a greater reduction among heavy vehicles. The percentage of speeding vehicles fell from 95.4% to 81.9% upstream and from 63.4% to 35.7% near the chicane, indicating improved compliance in the most critical section (P2). These findings demonstrate that SMDs can effectively reduce speeds and variability even in very short-term work zones, supporting their integration as low-cost safety measures.