美国养护工区特征分析(8)

美国养护工区特征分析

Likewise, work zones that are primarily daywork sometimes extend into the late evening.The most frequent period of work zone capacity impact has been9-11AM in all five snapshot studies, when roughly two-thirds or more of the work zones were identified as having lane closures.The least frequent hour for lane closures in our snapshot studies have been from 6-7 PM when only 26% of work zones were designated as having lane closures.

Lane closure temporal patterns, such as the one shown in Figure 2, have remained

generally consistent across the snapshot studies conducted in the same season (winter or summer). In winter, however, lane closures are weighted more towards dayworkProject Purpose

The purpose of the roadwork activity was a widely reported attribute of projects across all states. In some cases there was a state-standard set of purposes, in other cases, freeform text descriptions had to be interpreted. The records were grouped into four broad

categories (Bridge Work, Resurfacing/Paving, Roadway Construction and Rehabilitation, Other/Incidental Construction). Table 2 shows the frequency of each activity. Roadway construction and maintenance was the most likely reported purpose.

closures of long duration. Roughly one half of all bridge work activity takes

place during daylight hours. Bridge work is one of the most frequently reported

work zone purposes during the winter season.

operations had long work zone lengths and are the most likely activity for work zones with lane closures at night. Paving operations are far

more frequent in the summer season than in the winter season, dropping in

frequency by more than half.

likely because this work is largely reconstruction of existing facilities. The split of daywork and nightwork followed the average for all roadwork observed.

primarily as daywork. This category is difficult to characterize further as it

represents a disparate mix of construction and maintenance activities. National Measures of Work Zone Activity

From our analysis of work zone length, lane closure duration and lane closure type,

several high-level measures of work zone activity on the NHS are estimated. Excluding work zones on local streets, the number of work zone records was utilized to estimate a total number of work zones on the twenty states in our sample (2002-2003).Avisual inspection of NHS highway maps and records from both Arizona and Washington in